Brea City Council
June 2, 2026

M-1 Policies
● M-1.1 Caltrans Coordination. Work regularly with Caltrans to improve access to and from State Route 57, Imperial Highway (State Route 90), and Valencia Avenue and Carbon Canyon Road (State Route 142).
● M-1.2 Inter-Agency Coordination. Engage in federal, State, and regional planning efforts with Federal Highway Administration (FHWA), the Southern California Association of Governments (SCAG), Orange County Transportation Authority (OCTA), Orange County, adjacent cities, and other jurisdictions, as appropriate, to develop a transportation network that balances traffic flow and multi-modal needs.
● M-1.3 OCTA Coordination. Work with OCTA to ensure that the Master Plan of Arterial Highways is consistent with the City’s Master Plan of Roadways. ● M-1.4 Emerging Technology. Work with regional partners to plan for emerging transportation modes and technologies.
● M-1.5 Arterial Network System Coordination. Cooperate with surrounding jurisdictions to ensure the efficient operation of the arterial network system. ● M-1.6 Minimize Cut-Through Traffic. Work with Caltrans, OCTA, and surrounding jurisdictions to provide adequate capacity on regional routes for through traffic to minimize cut-through traffic on the local street system.
● M-1.7 Goods Movement on Regional Routes. Maintain safe and efficient goods movement on State routes and major arterials in support of the City’s economic vitality, business districts, and shopping centers.
● M-1.8 Carpooling. Facilitate and encourage carpooling for residents commuting outside the City and for employees traveling into the City, recognizing carpooling as a key alternative transportation mode that supports regional mobility and reduces congestion. ● M-1.9 VMT Reduction Facilities. Encourage the use of park-n-rides and other facilities and programs that support reduced vehicle miles traveled (VMT), such as mobility hubs, shared mobility services, and other multi-modal infrastructure. EJ M-1 Actions
● M-1a Participate in regional planning forums, organizations and agencies to ensure that the City’s concerns are considered at the regional level. ● M-1b Monitor land use, circulation planning, and the development review process of neighboring jurisdictions so that the City has an opportunity to identify impacts to Brea and make recommendations for consideration by those jurisdictions.

Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

● M-1c Implement traffic control strategies and coordinate with enforcement agencies to improve commercial vehicle safety and support the quality of life for Brea residents. ● M-1d Coordinate with Caltrans, OCTA, and surrounding jurisdictions to maintain and improve capacity on State highways and regional arterials to support access to the City’s business and shopping centers and to discourage cut-through traffic on local streets. ● M-1e Work with Caltrans to coordinate traffic operations and share surveillance and monitoring resources to improve traffic flow and support effective traffic enforcement.

Goal M-2: Provide a safe local circulation system that facilitates the efficient flow of traffic and goods throughout the City.

M-2 Policies
● M-2.1 Roadway Requirements. Require roadways to:
○ Be designed to be consistent with applicable federal, State, and local design and safety standards.
○ Meet the needs of multiple transportation modes and users, including children, seniors, and people with disabilities.
○ Be compatible with the streetscape and surrounding land uses. ○ Be maintained in accordance with best practices.
● M-2.2 Level of Service. Strive to maintain acceptable vehicular level of service at City intersections, per the City of Brea Transportation Impact Analysis (TIA) Guidelines. ● M-2.3 Non-Local Traffic. Discourage the flow of non-local traffic through neighborhoods. ● M-2.4 Traffic Management. Apply creative traffic management strategies to maintain efficient and orderly traffic flow, minimize vehicular congestion in areas with unique users (such as schools, and businesses with drive-through access) and other special situations. ● M-2.5 Trees. Promote the planting of locally native trees in the public right-of-way, including street trees and parkways, to provide shaded pathways, neighborhood cooling, and other benefits. EJ
● M-2.6 New Development – Transportation Studies. Require new development projects to prepare transportation studies and VMT analysis consistent with the City’s TIA Guidelines and to implement appropriate measures to mitigate CEQA impacts and address non-CEQA effects to the transportation network. ● M-2.7 Evacuation Routes. Incorporate necessary improvements to and perform maintenance on evacuation routes consistent with the Public Safety Element, and Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

according to applicable requirements identified in regional and local plans. ● M-2.8 Truck Route Network. Maintain, and update as needed, a designated local truck route network that facilitates access to business and shopping centers while reducing commercial vehicle effects on the community.
● M-2.9 Public Input in Transportation Changes. Support community participation in traffic control and management decisions through the City’s Traffic Committee. EJ ● M-2.10 School Zones. Work with the Brea Olinda Unified School District and private schools to facilitate safe circulation surrounding schools in the morning arrival and afternoon dismissal peak periods, and minimize queuing and parking impacts on public streets and residential areas within school zones. EJ
M-2 Actions
● M-2a Encourage through traffic to use arterial roadways, while maintaining appropriate access for local trips on collector and neighborhood streets, using traffic control devices, speed management, and other context-sensitive strategies. ● M-2b As part of the development review process, require development projects to study and address their effects on local roadway operations, as required by the City Traffic Engineer.
● M-2c Periodically review and assess the vehicular level of service along City facilities to determine, what, if any, improvements are warranted to maintain a safe and efficient flow of traffic throughout Brea. As part of this effort, prepare a nexus study to identify the specific traffic improvements necessary to support the City’s intersection Level of Service goals. Based on a thorough review of facility operations and funding availability, improvements may be included in the City’s planned maintenance operations, the City’s Capital Improvement Program, and/or required as part of project approval through the development review process.
● M-2d Develop and maintain traffic signal and communications systems, including video and data networks, to efficiently manage traffic flow and support public safety operations. ● M-2e Review and update the City’s designated truck routes as needed while considering the potential mobility conflicts and the location of sensitive land uses in the City. ● M-2f Evaluate and implement traffic calming measures in residential areas to manage vehicle speeds and enhance safety for pedestrians, bicyclists, and other roadway users. ● M-2g Incorporate public input into the planning and design of transportation facilities to enhance safety, accessibility, and responsiveness to community needs.

Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

● M-2h Utilize creative traffic and parking controls and methods to reduce congestion, improve circulation and parking availability, and enhance safety. ● M-2i Prepare a nexus study to determine the specific traffic improvements required to support the City’s intersection Level of Service goals.

Goal M-3: Provide a safe and convenient transportation network accessible for all transportation modes and users.

M-3 Policies
● M-3.1 Complete Streets Principles. Consider and implement best complete streets practices to facilitate travel and enhance safety for all road users regardless of travel mode. EJ
● M-3.2 Identify Gaps. Identify and address gaps in travel facilities serving vehicles, bicyclists, pedestrians, transit riders, and other users. EJ ● M-3.3 Safe Routes to School. Coordinate with public school districts and private schools to establish safe routes to school, promoting walking and biking to schools by developing transportation networks that support safe and convenient non-motorized travel for students and parents. EJ
● M-3.4 Context Sensitivity. Consider the land use and design context of the surrounding areas when designing new roadways and rehabilitating existing roadways, and partner with applicable outside agencies as needed.
● M-3.5 New Mobility Technologies. Monitor and evaluate the development of new mobility technologies and the considerations for implementation of improvements to facilitate a transportation network that accommodates all modes and users. ● M-3.6 Curb Management. Seek to implement curb zone changes to best match the needs of adjacent land uses and to facilitate non-motorized transportation choices while minimizing the effects to roadway conditions and on-street parking. ● M-3.7 Roadway Design Principles. Support roadway design principles that create a safe, pleasant, and comfortable experience for all road users including pedestrians and bicyclists. ● M-3.8 Traffic Calming. Use traffic calming methods within residential areas as needed to create a pedestrian-friendly circulation system, while accommodating local street patterns where feasible. Balance accommodations for automobiles, transit, bicycles, and pedestrians in the design of new streets and streetscape improvements. ● M-3.9 New Development – Multi-Modal Facilities. Require new development projects to Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

accommodate vehicles (including emergency vehicles), pedestrians, and bicycles through the dedication of land for public improvements such as roadways, wider sidewalks, and/or bicycle lanes, as appropriate and warranted by the project. ● M-3.10 Community Event Street Management. Support temporary street closures for community events that enhance resident quality of life, scheduling them during weekends or off-peak times. Implement traffic control plans for these closures that maintain safety for both participants and other roadway users.

M-3 Actions
● M-3a As part of the development review process, require applicable projects to study their effects on the walking, bicycling, and public transit networks and users (consistent with the City’s TIA Guidelines) and contribute their appropriate fair share to multi-modal transportation network improvements.
● M-3b When planning roadway facilities, incorporate complete streets concepts. Consider design elements for all modes and users that use streets in a context-sensitive manner. ● M-3c Continue to work with Brea Olinda Unified School District and other stakeholders to establish safety education and outreach campaigns for pedestrians and drivers, and to pursue Safe Routes to School projects and funding opportunities that encourage parents and children to walk or bike to schools within the City. ● M-3d When designing new roadways or rehabilitating existing roadways consider the overall movement of people by all modes and seek to provide design features that improve efficiency and safety for all.
● M-3e Seek and apply for grants to design and implement complete streets and safety projects consistent with the goals, policies, and actions of this plan. ● M-3f Engage the City’s Traffic Committee in evaluating and guiding the implementation of traffic calming principles and design treatments in response to resident requests.

Goal M-4: Develop extensive networks of public bikeway and community pedestrian facilities that enable and encourage non-motorized travel.

M-4 Policies
● M-4.1 System of Bikeways. Develop and maintain a comprehensive and integrated system of bikeways that promotes cycling for commuting and recreation. ● M-4.2 The Tracks at Brea. Encourage usage of The Tracks at Brea by improving walking and biking access to designated entry/exit points, implementing wayfinding signage, and coordinating with the adjacent cities to extend the existing facility from the existing terminus to Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

the western City limits and ultimately to the Whittier Greenway Trail to the west. EJ ● M-4.3 Pedestrian Connections. Provide for safe and convenient pedestrian connections to and from Downtown, other commercial districts, neighborhoods, and major activity centers within the City. EJ
● M-4.4 Users of All Abilities. Provide sidewalks, crosswalks, curb ramps, and pedestrian traffic signal treatments, including ADA-compliant facilities, that are safe and accessible for users of all abilities. EJ
● M-4.5 Birch Street Corridor. Establish the Birch Street Corridor between Downtown Brea and the Civic and Cultural Center/Brea Mall as a pedestrian and bicycle friendly travel way. ● M-4.6 New Development – Alternative Modes of Travel. Require new mixed use and multifamily developments to provide for the use of alternative modes of travel via internal trails or travel ways – public or private – for pedestrians, microtransit, and buses where feasible. Require new developments to include such features as well-designed sidewalks and parkways, bike lanes and paths, and dedicated bus turn-outs where feasible. ● M-4.7 Bicycle, Pedestrian, and Connectivity Improvements. Provide safe, attractive, and accessible bicycle and pedestrian facilities—such as secure bicycle parking, pedestrian-scale lighting, and landscaping—and to make improvements that enhance connectivity to key destinations like schools, parks, workplaces, and shopping areas that serve residents’ daily needs where feasible. EJ
● M-4.8 Emerging Travel Modes. Plan for emerging modes of travel, considering applicable regulations, infrastructure, education and enforcement needs to promote safety, accessibility and enjoyment for all users within the City. ● M-4.9 Caltrans Coordination. Coordinate with Caltrans to improve pedestrian and bicycle connectivity across and along State facilities (Imperial Highway, Valencia Avenue, and Carbon Canyon Road), and at SR 57 freeway on- and off-ramps. ● M-4.10 Bicycle and Pedestrian Connectivity. Plan neighborhood streets, pedestrian walks, and bicycle paths as a system of fully connected routes throughout the City. EJ ● M-4.11 Planning and Design for E-Bikes. Support the safe use of e-bikes and other electrified mobility devices through design, education, and enforcement measures consistent with best practices and regional guidance, including recommendations from the Orange County Grand Jury.
● M-4.12 Sidewalk Design Standards. Support the construction of sidewalks that meet or exceed minimum City standard widths to accommodate current accessibility standards or pedestrian needs, and include parkways or landscaped buffers to separate pedestrians from vehicular traffic, enhancing safety and comfort for all users. EJ Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

M-4 Actions
● M-4a Develop a comprehensive Citywide Active Transportation Plan (ATP) to guide the planning and implementation of bicycle and pedestrian facilities throughout the City.

Update the General Plan as needed following completion of the Citywide ATP to ensure consistency with its goals and recommendations.
● M-4b Incorporate State and national best practices when designing and implementing improvements to enhance pedestrian and bicyclist comfort, such as those recommended by Caltrans, the Federal Highway Administration (FHWA), and the National Association of City Transportation Officials (NACTO).
● M-4c Install secure bicycle parking at City-owned facilities where feasible. ● M-4d As part of the development review process, implement the following where feasible:
○ Provide project design features that support walking and biking and connect to the City’s current and planned walking and biking network.
○ Provide sidewalks and pedestrian ramps, repair or replace damaged sidewalks, and implement right-of-way improvements.
○ Construct and/or contribute to off-site improvements that enhance the pedestrian experience, including human-scale lighting, streetscaping, and accessible sidewalks adjacent to the site.
○ Provide supportive amenities such as safe, secure, and convenient bicycle parking. ○ Comply with the City’s Trip-Reduction and Travel-Demand Ordinance, as specified in Brea City Code 20.08.050.
● M-4e Include active transportation improvements in the City’s Capital Improvement Program (CIP).
● M-4f Consider bicycle and pedestrian access during site plan review for new development projects, consistent with the City’s Traffic Impact Analysis (TIA) Guidelines. ● M-4g Develop a wayfinding plan to guide pedestrians and bicyclists to The Tracks at Brea. Include useful information on wayfinding signs, such as distance and time, to promote walking and biking to destinations.
● M-4h Seek and apply for grants to implement bicycle and pedestrian facilities recommended in regional and local plans.
● M-4i Implement context-sensitive bicycle facilities that prioritize safety by incorporating buffered or protected bike lanes where appropriate.

Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

● M-4j Investigate opportunities to optimize the pedestrian experience. Where feasible, add sidewalk extensions and corner bulb-outs to reduce crossing distances and improve visibility of pedestrians.
● M-4k Evaluate opportunities to restrict right-turns on red or establish leading pedestrian intervals within the signal timing to improve safety for pedestrians crossing major roadways.

Goal M-5: Facilitate and encourage increased use of public transit and other multi-modal transportation services.

M-5 Policies
● M-5.1 Working Partnership with Public Transit Providers. Maintain a proactive partnership with all public transit providers including OCTA and Foothill Transit, to encourage adequate public transit service and support facilities, including efforts to restore and enhance transit service to eastern Brea in coordination with ongoing commercial revitalization and new housing development.
● M-5.2 Regional Destinations. Collaborate with neighboring cities and regional transportation providers to encourage the provision of microtransit (e.g., shuttles), paratransit, and affordable transportation programs for residents to desirable locations and destinations in the region (e.g., youth and senior program providers, regional shopping centers, medical facilities, etc.).
● M-5.3 Design Features. Incorporate design features into public improvement projects that promote and support the use of public and alternative modes of transportation. ● M-5.4 Mobility Hubs. Coordinate with public transit providers and local businesses to establish mobility hubs with enhanced first/last mile amenities for transit, rideshare, walking, and biking at the Brea Mall Transit Center and other major activity centers. ● M-5.5 Bus Stop Locations. Prioritize the placement of curbside bus stops near major destinations and intersections as a priority over other parking uses, to enhance convenience and accessibility for transit users.
● M-5.6 Bus Shelters. Promote the funding, design, construction, and maintenance of highquality bus shelters that protect riders from weather and encourage transit use, while balancing opportunities for advertising shelters that generate revenue for the City. EJ ● M-5.7 Transportation Needs of Seniors and Students. Plan and evaluate transportation services to address the daily mobility needs of seniors and students, including transit options that enhance access, convenience, and safety for these populations. EJ ● M-5.8 New Development – Transit Connections. Require new developments to Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

facilitate the use of transit for commute and non-commute trips, and include such features as connections to nearby bus stops, space for transit facilities, transit-supporting land uses, and information on available transit services, where feasible.

M-5 Actions
● M-5a Continue to work with local and regional transit operators such as OCTA and Foothill Transit to support integration and service between local bus, Bus Rapid Transit (BRT), and passenger rail service and stations, and generally improve service, including frequency and reliability.
● M-5b As part of the development review process, require that new developments include design features that support public transit use.
● M-5c Monitor federal, State, and OCTA transit funding programs to identify potential sources of funds for transit programs in Brea. Pursue any potential funding through the identified programs.
● M-5d Seek to improve pedestrian and other non-motorized access to public transit stops and mobility hubs in the City to encourage more frequent transit usage.

Community Resources Element
Goal CR-1: An accessible, integrated system of parks and recreational amenities that meet the needs of all residents.

CR-1 Policies
● CR-1.1 Acreage Requirements. Ensure that at least five acres of developed parkland and appropriate amenities are available for every 1,000 Brea residents. Require all new residential development projects to contribute toward this standard through mechanisms such as land dedication, in-lieu fees, or park development fees, consistent with the Quimby Act and City regulations.
● CR-1.2 Diverse Recreation Types. Promote a wide variety of public and private facilities and recreational amenities distributed equitably throughout the community to foster a comprehensive system that serves all residents, with a special focus on environmental justice communities. Amenities may include inclusive playgrounds, outdoor fitness stations, pocket parks, and trail extensions. EJ
● CR-1.3 Service Area Radius. Focus new park facilities in areas that are outside 1/2-mile walking radius from an existing “green space” (park, trail, or natural open space area) and in environmental justice communities (see Figure CD-5) and enhance options for residents to access these facilities through safe walking, bicycling, and transit routes.

Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

Physical barriers such as SR-57 and Imperial Highway should also be considered when evaluating service area and access. EJ
● CR-1.4 Park and Trail Maintenance. Maintain and enhance existing parks and trails to meet the evolving needs of the community. EJ
● CR-1.5 Design Standards. Implement established design, construction, and facility maintenance standards to ensure that existing and future City amenities are of highquality regarding safety, utility, equity, environmental stewardship, and aesthetic quality. ● CR-1.6 Funding. Explore funding options and innovative partnerships to bolster and support the development, improvement, and maintenance of City parks and recreational amenities, with a focus on underserved areas. EJ
● CR-1.7 Trail Extensions. Support development of extended local trails and urban pathways that provide access to parks, recreational facilities, and other areas with open space and nature. EJ
● CR-1.8 Community Engagement. Collaborate with residents and the wider community to continually improve and adapt facilities and programs based on their interests and feedback. EJ
● CR-1.9 Regional Collaboration. Work with Orange County, Los Angeles County, the State, and other public and private partners to conserve, protect, and enhance parks, trails, and recreational resources.

CR-1 Actions
● CR-1a Evaluate new development projects for potential negative effects on nearby public parks, such as traffic, noise, or pollution from non-recreational land uses. Encourage new uses or facilities, including new recreation facilities, to be planned in a way that maintains or enhances opportunities for casual, unstructured use and avoids the unnecessary displacement of existing park functions.
● CR-1b Pursue available resources to fund parkland and facility maintenance, acquisition, and development, such as Federal and State grants, private donations, and gifts and endowments.
● CR-1c Periodically review and update the park in-lieu fee ordinance as necessary to better reflect current costs and needs to address park demand generated by development.
● CR-1d Organize periodic community workshops to identify areas for improvement within the existing City-owned parks and trails network.

Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

● CR-1e Connect the Tracks at Brea to La Habra to complete the OC Loop.

Goal CR-2: High-quality human services that enhance the livelihood of Brea residents of all ages and abilities.

CR-2 Policies
● CR-2.1 Recreation and Human Services. Provide, facilitate (solely or in partnership), and/or support human services or recreational programming—including accessible childcare resources—responsive to the needs of all ages, genders, cultural, and socioeconomic groups. EJ
● CR-2.2 Multigenerational Programming. Encourage inclusive human services and recreation opportunities that bring together people of all ages to build intergenerational connections.
● CR-2.3 Funding. Identify innovative funding and development opportunities to support and sustain the City’s human services and recreation programs, especially for underserved populations. EJ
● CR-2.4 Encourage Wellness. Encourage the development of health and wellness, fitness, and/or other recreation programs and activities. ● CR-2.5 Partnerships. Partner with other public agencies, non-profit, and public and private organizations to develop comprehensive programming that promotes the wellbeing of Brea residents of all ages. EJ ● CR-2.6 Community Input. Collaborate with community members to ensure that programming reflects the diverse needs and interests of Brea community members. EJ ● CR-2.7 Multilingual Recreation and Community Services. Encourage the development and delivery of multilingual recreation, community programs, and information to foster inclusivity and equitable access for non-English-speaking residents. EJ ● CR-2.8 Volunteer Opportunities. Offer meaningful volunteer opportunities for people of all ages and abilities to support City services and programs as feasible. EJ CR-2 Actions
● CR-2a Continue offering cultural and recreational classes and programs for all ages at City facilities such as the Brea Community Center and parks across the community. ● CR-2b Continue offering human services programs to ensure that residents of all ages and abilities have access to childcare referrals and mental health services.

Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

● CR-2c Research and apply for Federal, State, regional, private, and philanthropic grants that support human services and recreation opportunities. ● CR-2d Update and evaluate community awareness campaigns regarding well-being of youth, families, and available resources.
● CR-2e Promote volunteer opportunities to support Brea human services and recreational programs.
● CR-2f Engage with residents through surveys, social media, and other platforms to gather input on the planning and programming of City-hosted services and events, ensuring they are engaging, family-friendly, and serve the broader Brea community. ● CR-2g Translate flyers, websites, signage, registration forms, and program guides into the most commonly spoken languages in the community.

Goal CR-3: The preservation and maintenance of open spaces for nature, resource management, recreation, and scenic enjoyment.

CR-3 Policies
● CR-3.1 Open Space Preservation. Continue efforts to preserve open space lands for purposes of habitat protection, resource conservation, flood hazard management, public safety, and overall community benefit, in collaboration with neighboring jurisdictions and other relevant agencies, contributing to the statewide California 30x30 goal of permanent land conservation.
● CR-3.2 Sensitive Species and Habitats. Support the conservation of sensitive species, plant communities, and wildlife habitats to the maximum extent feasible through open space dedication, creative site design, and other workable actions. ● CR-3.3 Hillside Preservation. Continue efforts to conserve sensitive hillside, ridgelines, canyons, and open space areas, and protect wildlife corridors and habitat connectivity, in accordance with standards set forth in the Brea City Code. ● CR-3.4 Mature Vegetation. Encourage all entities involved in development, redevelopment, and landscape maintenance to avoid removing mature vegetation.

Promote the inclusion of a variety of sizes of new vegetation in projects to balance initial aesthetic landscape value with the long-term health and sustainability of the landscape. ● CR-3.5 Rewilding. Explore rewilding opportunities and other ecological restoration projects aimed at increasing biodiversity and restoring natural processes. ● CR-3.6 Open Space Education. Work with State, Federal, and community partners to develop educational and other materials that promote the preservation and conservation Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

of Brea’s natural resources, to the extent practical.

CR-3 Actions
● CR-3a Assess development proposals for potential impacts to important geologic and scenic landform features pursuant to the California Environmental Quality Act (CEQA).

Require appropriate mitigation measures, including environmentally sensitive site planning and grading, revegetation and open space dedication, for significant impacts. Consider important topographical features, watershed areas, ridgelines, soils, and potential erosion problems in the assessments. Ensure the new development is compatible to adjacent open space lands.
● CR-3b Reassess the City’s Hillside Zoning Ordinance to minimize the encroachment of new development near areas of open space, especially sensitive areas, and to consider the unique impacts of fire hazards in hillside areas.
● CR-3c Collaborate with Federal, State, regional, local, non-profit, environmental and conservation organizations, and private entities to conserve, protect, and enhance open spaces and natural resources throughout Brea’s Planning Area. ● CR-3d Prepare and distribute resources guides and brochures regarding public access to regional open spaces, and how visitors can aid in the protection of these areas. ● CR-3e Avoid development impacts to identified or potential wildlife corridors to the maximum extent feasible, based on site-specific biological surveys prepared by a qualified wildlife biologist and the best available scientific data. Where avoidance is not feasible, require project design features that preserve habitat connectivity and support wildlife movement, subject to City review and coordination with applicable wildlife agencies. Such standards may include, but are not limited to:
○ Minimum Corridor Widths: Maintain wildlife movement corridors at widths consistent with the best available scientific guidance applicable to target species and regional conditions.
○ Wildlife-Permeable Fencing: Install fencing that allows for wildlife movement and prohibits the use of solid walls or impermeable barriers within or adjacent to corridors.
○ Lighting Design: Design and install lighting that minimizes spillover into adjacent wildlife corridors through shielding, direction, and low-intensity fixtures. ●○ Crossing Design: Incorporate wildlife crossing structures where roadways or driveways intersect corridors, designed in accordance with best available science and species-specific needs.

Goal CR-4: A community where visual resources reflect Brea’s natural beauty and help Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

guide responsible development.

CR-4 Policies
● CR-4.1 Trails, Recreation Areas, and Viewing Areas. Encourage the development of inclusive trails, recreation areas, and viewing points in locations where residents and visitors can enjoy Brea’s scenic resources, while avoiding intrusion into sensitive natural areas.
● CR-4.2 Key Roadways. Recognize the aesthetic value of visually sensitive roadways through thoughtful development practices consistent with the Brea City Code. ● CR-4.3 Tree Resources. Manage mature trees, particularly native species, to preserve their ecological benefits and their contribution to Brea’s visual character, in accordance with the City’s Tree Preservation Ordinance.
● CR-4.4 Regional Collaboration. Work with Orange County, Los Angeles County, State, and other appropriate public and private agencies to conserve, protect, and enhance natural resources, particularly within the sphere of influence.

CR-4 Actions
● CR-4a Assess development proposals, including those in Brea’s Sphere of Influence, for potential impacts to important visual resources pursuant to CEQA. Require appropriate mitigation measures for all significant impacts. Consider important ridgelines, creeks, open space, views of the surrounding hillsides, and light and glare effects. ● CR-4b Maintain and apply existing design standards to preserve views, vistas, and defining natural features along prominent roadways and visually sensitive areas. ● CR-4c Install informational signage and viewing platforms at local scenic vistas to enhance public access.
● CR-4d Evaluate opportunities to strengthen tree protection standards and preservation measures.

Goal CR-5: A resilient ecosystem that safeguards habitats for biological resources and wildlife.

CR-5 Policies
● CR-5.1 Habitat Conservation. Support efforts to identify and conserve suitable habitats, in accordance with State and Federal resource agency requirements. ● CR-5.2 Local Coordination. Coordinate with local and regional public and private organizations to implement strategies and programs that protect and preserve biological resources within Brea.

Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

● CR-5.3 Invasive Plant Species. Collaborate with regional partners to monitor and manage invasive plant species, minimizing their impacts on local ecosystems and preserving native biodiversity.
● CR-5.4 Protective Landscaping. Encourage Promote landscape planting that excludes avoids known invasive plant species, as identified by recognized environmental organizations or applicable regulatory agencies, and encourages native plant species. ● CR-5.5 Sustainable Landscaping. Encourage Promote landscaping that incorporates native and pollinator-supporting plant species, minimizinges the need for herbicides and pesticides and that provides food, water, shelter, and nesting sites for birds, butterflies, beneficial insects, and other creatures that both help maintain the landscape and restore the larger ecosystem.
● CR-5.6 Riparian Habitats. Encourage development practices that protect riparian habitats. Where impacts are unavoidable, require mitigation measures in accordance with applicable regulations.
● CR-5.7 Wildlife Corridors. Encourage the preservation of critical wildlife corridors and habitat connectivity, including as part of the development review process. ● CR-5.8 Urban Canopy. Preserve and expand the urban canopy of trees and vegetation throughout the community to help reduce urban heat, improve air quality, reduce stormwater runoff, enhance aesthetics, and support biodiversity. ● CR-5.9 Outdoor Lighting. Protect local character, enhance visual safety, and mitigate the harmful effects of light intrusion and pollution.
● CR-5.10 Biological Resource Education. Collaborate with agencies, non-profit organizations, and other community groups to promote awareness about steps residents can take to help preserve and enhance biological resources in the area.

CR-5 Actions
● CR-5a Maintain a buffer area between natural waterways and urban development to protect water quality and riparian areas, as deemed necessary. ● CR-5b Continue to assess development proposals for potential impacts to significant natural resources pursuant to the California Environmental Quality Act (CEQA) and associated State and Federal regulations. Require appropriate mitigation for all significant impacts if impact avoidance is not possible. Mitigation measures for habitat and species may include, but are not limited to, avoidance, enhancement, restoration, or a combination of any of the three. Address the following subjects in impact assessment as applicable to Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

individual development proposals:
○ Natural communities;
○ Riparian and wetland habitat (including potential jurisdictional areas); ○ Coastal sage scrub habitat;
○ Coast live oak habitat;
○ Rare and endangered plant and animal species;
○ Habitat fragmentation (including disruption of wildlife corridors); and ○ Creeks, blue line streams, and associated tributaries. ● CR-5c Continue to require development proposals to consult with regulatory agencies, including the United States Fish and Wildlife Service (USFWS), California Department of Fish and Game (CDFG), United States Army Corp of Engineers (USACE), about natural resources if the following occurs on the project site:
○ Potential take or substantial loss of occupied habitat for any threatened or endangered species; or
○ Existing drainage features (jurisdictional area) are located within the project site. ● CR-5d Work with local, regional, State and Federal partners to seek funding for wildlife corridor improvements such as dry wedges, culverts, overcrossings at priority locations with high instances of roadkill.
● CR-5e Evaluate the potential of a to implementor a Dark Sky, Lights Out, or ordinance or other similar regulatory mechanism or ordinance to reduce light pollution and minimize impacts on wildlife species.
● CR-5f Continue to maintain the City’s tree inventory and use it to periodically identify areas where the urban canopy can be expanded. Establish a comprehensive citywide tree management program with the following elements:
○ Maintain a 3-5 year tree trimming schedule for City-maintained trees. ○ Encourage a 1:1 tree replacement ratio for both public and private tree removals. ○ Target new tree plantings in areas which are lacking and underserved by landscape, canopy and green spaces strategizing where plantings can be most successful. ○ Update the 1999 Master Street Tree Plan to reflect current best practices. No trees or other plant species that are on the California Invasive Plant Council (Cal-IPC) Invasive Plant list or on their “watch list” for invasiveness are permitted. ● CR-5g Establish objective development standards for subdivision approvals that require design measures to maintain connectivity and permeability for wildlife movement.

Goal CR-6: A community that preserves, protects, and celebrates artistic, cultural, and Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

historic resources that define Brea’s identity.

CR-6 Policies
● CR-6.1 Cultural Services. Offer and support cultural services and programs and events that reflect the rich cultural heritage of Brea. EJ
● CR-6.2 Cultural Facilities. Maintain cultural facilities such as the Curtis Theatre, the Brea Gallery, and the Community Center as key cultural arts venues. ● CR-6.3 Placemaking. Integrate public art, murals, and cultural expression into streetscapes, parks, and civic spaces to enhance visual interest and create memorable places.
● CR-6.4 Historic Resources. Evaluate the condition of historical buildings, the costs of rehabilitation, and the feasibility of preservation or conservation alternatives when considering the demolition or movement of historic structures. ● CR-6.5 Archaeological and Paleontological Resources. If significant archaeological or paleontological resources are discovered, evaluate their cultural relevance, physical condition, economic factors, feasibility, and other key aspects. ● CR-6.6 Human Remains. Ensure that human remains are treated with sensitivity and dignity. Maintain compliance with the provisions of California Health and Safety Code Section 7050.5 and California Public Resources Code Section 5097.98. ● CR-6.7 Tribal Consultation. In accordance with State, local, and Tribal intergovernmental consultation requirements, consult with Native American tribes that may be impacted by proposed development and land use policy changes, as necessary. ● CR-6.8 Planning Considerations. Integrate cultural resources into everyday planning processes through careful and creative design review and prioritization of historic and cultural history in new design development. EJ
● CR-6.9 Regional Collaboration. Work with Orange County, Los Angeles County, the State, and other public and private partners to establish programs and funding mechanisms to preserve, restore, and enhance cultural, historic, and archaeological sites. ● CR-6.10 Public Engagement. Continue to foster community awareness and engagement of Brea’s history through maintenance of the Brea Museum and Historical Society, and the Olinda Oil Museum and Trail. EJ
● CR-6.11 Celebrate Heritage. Promote Brea’s heritage through artwork, context-sensitive design, and events throughout the City. EJ
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CR-6 Actions
● CR-6a Organize City-sponsored cultural celebrations that highlight Brea’s diverse communities through food, music, dance, storytelling, and art. ● CR-6b Continue to research all types of possible funding sources and financial assistance to help promote, preserve, and restore historical resources in Brea. Such funding sources can include tax incentives, Federal and State funds, grants, awards, loans, and other financial sources.
● CR-6c Continue to add resources that meet the City’s Historic Preservation Ordinance.

Collaborate and assist efforts to list historic resources and structures to various Federal and State historic registers, as deemed necessary.
● CR-6d Continue to work with Community Services Department to promote Brea’s heritage through artwork, signs, preservation, recreation programs, events, and historical structures throughout the City and in its park lands.
● CR-6e Continue to work with the Brea Museum and Historical Society to increase awareness of Brea’s historic resources and the importance of their preservation.

Goal CR-7: High-quality educational facilities and lifelong learning opportunities that empower residents of all ages to gain the knowledge, skills, and resources needed for personal and professional growth.

CR-7 Policies
● CR-7.1 Support Public Education. Promote and support high quality public education by working closely with the Brea Olinda Unified School District in determining and meeting community needs for public education and related activities. ● CR-7.2 School Siting. Ensure that educational facilities are designated and planned to accommodate existing and future capacity and are located nearby planned residential development. EJ
● CR-7.3 Yearlong Lifelong Learning. Promote lifelong learning opportunities for residents of all ages, including adult education programs, vocational training, community college courses, and library services that enhance personal and professional development throughout the calendar year.
● CR-7.4 Library Resources. Collaborate with Orange County Public Library to encourage the provision of library resources that meet the educational, cultural, civic, business, and lifelong learning needs of all residents.

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● CR-7.5 Joint Use Agreements. Maintain existing joint use agreements with the Brea Olinda Unified School District to make existing recreational, performance, and exhibit spaces accessible to the general public. EJ
● CR-7.6 Higher Education. Promote opportunities to collaborate and provide educational opportunities with nearby post-secondary education institutions such as California State University Fullerton and Fullerton College.
● CR-7.7 Arts and Education. Pursue partnerships with the Brea Olinda Unified School District, local public and private colleges and universities, and private organizations to support cultural arts programs and education.

Public Safety Element
Goal PS-1: A community that is minimally impacted by wildland and urban fires through implementation of proactive fire hazard abatement strategies.

PS-1 Policies
● PS-1.1 Services and Facilities. Provide adequate fire prevention services and facilities to meet the service standards identified by the Fire Department. EJ ● PS-1.2 Fire Hazard Identification. Maintain and regularly update the City’s Fire Hazard Severity Zones map (Figure PS-1) for changes in fire hazard severity zones consistent with changes in hazard designations by CAL FIRE.
● PS-1.3 City Standards. Require that all development in High Fire Hazard Severity Zones (HFHSZ) and Very High Fire Hazard Severity Zones (VHFHSZ) meet Fire Hazard Severity Zone standards as designated by City Ordinance.
● PS-1.4 Regional Coordination. Continue to coordinate with the County of Orange, the Orange County Fire Authority (OCFA), and the Carbon Canyon Fire Safe Council to include Brea in updates to the Local Hazard Mitigation Plan and Community Wildfire Protection Plan and investigate the possibility of preparing a plan component specific to the Brea community.
● PS-1.5 Development in Very High Fire Hazard Severity Zones. Minimize new residential development in VHFHSZs to the extent feasible. ● PS-1.6 Fire Protection Plans. Require adequate fire protection plans and emergency vehicle access for new developments in VHFHSZs.
● PS-1.7 Fire Protection Buffers. Require fire breaks and fuel breaks between natural areas and developed areas susceptible to wildland fires, particularly in the VHFHSZ. Fire Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

breaks (i.e. gaps in vegetation or combustible material achieved by completely scrapping an area to bare mineral soil) and fuel breaks (i.e. where vegetation is reduced in size to slow progression but is still present) shall be maintained at private expense and on private property in compliance with the applicable standards and regulations of the Fire Department.
● PS-1.8 Fire Safe Design. Encourage fire safe design (i.e. fire-resistant building and site design, materials, and landscaping) for development within VHFHSZs as part of the development review process.
● PS-1.9 Fire Hazard Reduction Projects. Coordinate with the Fire Department to identify and maintain fire hazard reduction projects, including community fire breaks and private road and public road clearance.
● PS-1.10 Standards for New Development. Require ongoing brush management, fuel management/modification, defensible space, fire-resistant landscaping, visible home and street addressing and signage, and other project design features for new development located in High and Very High Fire Hazard Severity Zones as part of the review process. ● PS-1.11 Rebuilding After a Fire. Coordinate with the Fire Department to identify building and site design methods or other methods to minimize future damage if new structures are proposed to be in the High Fire Hazard Severity Zone or Very High Fire Hazard Severity Zone when rebuilding after a fire.
● PS-1.12 Adequate Water Supply. Require development to demonstrate conclusively that there is adequate water capacity to provide necessary fire protection services. ● PS-1.13 Response Time. Require all new development to demonstrate that fire response times and service standards are maintained, as determined by the Brea Fire Department and any adopted strategic plans.
● PS-1.14 Access. Require sufficient ingress/egress access points in all new development to support firefighting activities, as determined by the Fire Department. ● PS-1.15 Education. Educate community members (residents, builders, property owners, employers) on fire hazards, fire safety measures, and local, regional, State, and Federal assistance programs, with a special focus on at-risk populations, such as those with limited mobility EJ.
● PS-1.16 Subdivision Map Act. Ensure compliance with the Subdivision Map Act requirements for structural fire protection and suppression services, subdivision requirements for on/off-site improvements, ingress and egress, street standards, and other concerns.

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● PS-1.17 Building and Fire Codes. Require that all new developments in the City comply with local, State, and Federal regulatory standards such as the California Building and Fire Codes as well as other applicable fire safety standards. ● PS-1.18 Critical Facilities and Structures. Locate, when feasible, new essential public facilities and infrastructure outside of VHFHSZs, including but not limited to, hospitals and health care facilities, emergency shelters, emergency command centers, emergency communication facilities, and utilities or identify construction methods or other methods to minimize damage if these facilities must be located in VHFHSZs. ● PS-1.19 Mutual Aid. Maintain mutual aid agreements with the State, County, and neighboring jurisdictions including for disaster response and evacuation assistance. ● PS-1.20 Public Information. Continue annual public information programs that explain the City’s Emergency Preparedness Program and other emergency preparedness strategies, including defensible space and evacuative routes, focusing on the most vulnerable communities such as those in the Very High Fire Hazard Severity Zones. EJ PS-1 Actions
● PS-1a Maintain and regularly update the City’s Fire Hazard Severity Zones Map for changes in fire hazard severity zones consistent with changes in hazard designations by CAL FIRE.
● PS-1b Maintain an ongoing fire inspection program to reduce fire hazards associated with multifamily development, critical facilities, public assembly facilities, industrial buildings, and nonresidential buildings.
● PS-1c Mitigate, as feasible, existing nonconforming development to contemporary fire safety standards, including road standards and vegetative hazards. ● PS-1d Assess site constraints when considering land use designations near wildlands to avoid or minimize wildfire hazards as part of a land use update or amendment. ● PS-1e Locate, design, and construct development to provide adequate defensibility against wildland fires and minimize the risk of structural loss from wildland fires. ● PS-1f Design development on hillsides and canyons to reduce the increased risk of fires from topographic features (e.g., steep slopes, ridge saddles). ● PS-1g Review proposed development projects and street networks to evaluate the accessibility for fire engines and other emergency response functions. ● PS-1h Conduct periodic evaluations on fire flow pressures in the City in conjunction with Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

updates to the Water Master Plan. Collaborate with the appropriate water providers on necessary upgrades to ensure adequate fire protection.
● PS-1i Work with CAL FIRE, United States Forest Service, United States Geologic Service, and applicable nongovernmental agencies to jointly create a plan to address post-fire recovery activities and projects that allow burned areas to fully recover and minimize repetitive losses and further damage.
● PS-1j In the event of a significant wildfire, the City shall immediately coordinate with relevant Federal, State, and local agencies, including but not limited to the USDA, USFS, CAL FIRE, the Orange County Flood Control District, and the Orange County Fire Authority to establish and implement, as feasible, a flooding and debris flow prediction and monitoring program. The intent of the program shall be to map and assess the likelihood of debris flow (in %), potential volume of debris flow (in m3), and combined relative debris flow hazard. In the event that a flood or debris flow risk is predicted during a subsequent storm event, implement procedures contained in the Emergency Operations Plan to notify residents and business owners of evacuation orders in affected areas. This action is written and adopted with the understanding that the City of Brea does not possess the resources to implement such a monitoring program independently and must rely on the expertise and resources of outside agencies.
● PS-1k Continue to require that all new habitable structures be designed in accordance with the most recent California Building and Fire Codes with local amendments adopted by the City, including the use of fire sprinklers in residential structures.

Goal PS-2: Reduce risk to the community from seismic activity and geologic conditions, including ground shaking, fault rupture, liquefaction, and landslides.

PS-2 Policies
● PS-2.1 Geologic Hazard Identification. Maintain and continuously update the City’s geologic and seismic hazards map (Figure PS-3) consistent with updates from the California Geologic Survey and local surveys.
● PS-2.2 Hillside Development. In areas subject to the City’s Hillside Zoning Ordinance, require a Geotechnical Investigation per CBC Chapter 18, Section 1803.1 to consider effects of the proposed development on adjacent upslope and downslope areas as well as on the site itself.
● PS-2.3 Alquist-Priolo Act. Enforce development requirements, such as seismic study analyses, project siting, and project design features for proposed developments within the earthquake fault zones identified on the maps prepared by the State geologist (data shown in Figure PS-2) pursuant to the Alquist-Priolo Act. ● PS-2.4 Building Codes. Adhere to the latest California Building Codes, Orange County Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

Grading and Excavation Code, and regulations governing earth work and grading during construction, and hillside grading guidelines to minimize erosion; update local codes periodically for the latest advances.
● PS-2.5 Critical Infrastructure and Facilities. Require that existing and future critical infrastructure and facilities (e.g., police, medical facilities, fire, roads, reservoirs, etc.) incorporate site-specific seismic structural design.
● PS-2.6 Liquefaction. Require special site-specific studies for new developments in areas potentially subject to liquefaction (shown in Figure PS-3) to determine the nature and extent of possible liquefaction and to identify engineering and development siting measures.
● PS-2.7 Education. Compile and distribute earthquake preparedness information to residents, business owners, and schools; work with partners to conduct periodic inspections and preparedness events.
● PS-2.8 Retrofitting Buildings. Encourage owners of potentially hazardous buildings (e.g., mobile homes and soft-story structures) to assess seismic vulnerability and conduct seismic retrofitting as necessary to improve resistance to earthquakes. ● PS-2.9 Historic Hazards. Discourage development in identified potential and historical landslide and flood plain areas which cannot be mitigated through regulation. ● PS-2.10 Maintain Water Supply. Ensure that water supplies are not interrupted by seismic events such as surface rupture, ground shaking, ground failure, or dam failure.

PS-2 Actions
● PS-2a Review development proposals to ensure compliance with California Health and Safety Code Section (Earthquake Protection Law), which requires that buildings be designed to resist stresses produced by natural forces such as earthquakes and wind. ● PS-2b Update building, zoning, and other applicable codes as needed to ensure adopted standards mitigate potential seismic hazards and comply with the Alquist-Priolo Act and Unreinforced Masonry Law.
● PS-2c Establish a public relations and education program to increase public awareness of potential geologic and seismic hazards in the community, their associated risks, and preparedness strategies.
● PS-2d Enact an ordinance which requires a preliminary soils report, prepared by a civil engineer who is registered by the state. The report shall be based upon adequate test borings or excavations, of every subdivision, where a tentative and final map is required Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

pursuant to Section 66426 of the Government Code.

Goal PS-3: Protect the community from potential flood hazards.

PS-3 Policies
● PS-3.1 Flood Hazard Identification. Maintain and continuously update the City’s flood map (Figure PS-5) consistent with FEMA map amendments and improvements to local drainage facilities.
● PS-3.2 New Development. Avoid and minimize flood risks for new development. ● PS-3.3 Areas Susceptible to Flooding. Reduce flood hazards in developed areas susceptible to flooding (i.e. 100-year floodplain and areas known to the City to flood during intense or prolonged rainfall events) and require new development in these areas to incorporate measures designed to mitigate flood hazards. ● PS-3.4 Education. Educate the community regarding flood prevention information and notify residents and motorists of impending flood hazards and evacuation procedures. EJ ● PS-3.5 Joint Use of Flood Control Facilities. Develop flood control facilities as parks, nature trails, golf courses, or other types of recreational facilities or joint-use facilities that can withstand periodic inundation, to the extent feasible. ● PS-3.6 Interagency Coordination. Coordinate with neighboring jurisdictions and public agencies responsible for flood protection to consider the impact to flooding and flood control measures on properties within Brea resulting from development in other jurisdictions.
● PS-3.7 Stormwater Runoff. Require new developments that add substantial amounts of impervious surfaces to integrate low impact development (LID) best management practices (BMPs) to treat stormwater runoff and to reduce stormwater runoff rates to predevelopment flows. ● PS-3.8 Critical Facilities. Prohibit development of new essential and critical facilities and lifeline services in the 100-year floodplain.
● PS-3.9 Open Space Area. Preserve open space areas for flood mitigation when possible. ● PS-3.10 Flood Control Facilities. Continue to coordinate with the Orange County Flood Control District to encourage the improvement of channel segments to alleviate local flooding, in accordance with the City’s Stormwater Program. ● PS-3.11 Infrastructure Maintenance. Maintain an active storm drain inspection program.

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● PS-3.12 Water Storage Facilities. Evaluate and monitor water storage facilities to determine which facilities are not self-contained and might pose an inundation hazard to downstream properties.

PS-3 Actions
● PS-3a Monitor changes in Federal and State laws and regulations related to local flood protection, including the National Flood Insurance Program (NFIP), and incorporate necessary changes into the Municipal Code, the City’s Emergency Operations Plan, and building codes as required and ensure that the City’s regulations continue to require that new development within flood hazard zones is consistent with this Safety Element and is required to meet the flood protection requirements of State law. ● PS-3b Provide information on flooding, flood control on private property, floodplains, and flood preparedness to the public.
● PS-3c Communicate with FEMA annually regarding updates to Flood Insurance Rate Maps (FIRMs) and Letter of Map Amendments.
● PS-3d Periodically review county, State, and Federal flood control best practices and incorporate appropriate standards into the Municipal Code. ● PS-3e Adopt a flood hazard map and supporting data complaintcomplaint with CBC Chapter 16, Section 1612
Goal PS-4: Protect the community by ensuring safe transport, use, storage, and disposal of hazardous materials within the City.

PS-4 Policies
● PS-4.1 Regulations. Enforce the California Fire Code as it regulates the use of hazardous materials, ensuring appropriate laws are followed and precautions are taken for the type and amount of hazard being created.
● PS-4.2 Measures to Reduce Risks. Require facilities that handle hazardous waste and materials to implement measures that reduce the risks associated with hazardous material production, storage, and disposal; incorporate the standards of the Hazardous Waste Management Plan for Orange County with regard to siting, development controls, and review procedures.
● PS-4.3 Transport. Limit the transport of hazardous waste and materials to designated routes.
● PS-4.4 Emergency Response. Ensure that the Fire Department can continue to respond safely and effectively to a hazardous materials incident in the City.

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● PS-4.5 Regional Compliance. Coordinate with responsible Federal, State, and county agencies to identify and regulate the disposal of toxic materials. ● PS-4.6 Education. Prepare and distribute educational materials to the community regarding illegal dumping, the dangers of hazardous waste, and City and County hazardous waste management plans. EJ
● PS-4.7 Oil Fields. Work closely with responsible State and Federal agencies to ensure that active oil field operations comply with all current regulations and, once oil field operations cease, that appropriate closure and clean-up activities occur. ● PS-4.8 Abandoned Oil Facilities. Continue to support the regulations of the California Geologic Energy Management Division (CalGEM) regarding abandoned oil facilities. ● PS-4.9 Remediation. Require comprehensive investigation, disclosures, and remediation of any former oil field property proposed for an alternative use, in compliance with all applicable Federal, State, and local regulations.

PS-4 Actions
● PS-4a As part of the development review process, require projects that would result in significant risks associated with hazardous materials to include measures to address the hazards and reduce the risks to an acceptable level.
● PS-4b Continue to require the submittal of information to the Fire Department regarding hazardous materials manufacturing, storage, use, transport, and/or disposal by existing and proposed businesses and developments.
● PS-4c Continue to promote off-site hazardous materials and/or electronic waste drop-off.

Goal PS-5: A community resilient to changing environmental patterns, including severe weather events and other adverse effects on public health, well-being, and safety.

PS-5 Policies
● PS-5.1 Community Preparedness and Engagement. Educate the community regarding potential hazards caused by climate change and develop programs and educational material to encourage public readiness.
● PS-5.2 Collaboration. Collaborate with local, regional, State, and/or Federal jurisdictions and agencies on climate resiliency and adaptation strategies. ● PS-5.3 Energy Supply. Promote plans and programs that increase sustainable energy sources.

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● PS-5.4 Water Supply. Promote plans and programs and collaborate with local, regional, State, and Federal jurisdictions to increase sustainable water sources and protect water infrastructure.
● PS-5.5 Programs. Implement necessary actions and programs to improve drought preparation and response, especially for the most vulnerable community members. ● PS-5.6 Leadership. Demonstrate leadership in local climate planning efforts through a range of tangible actions and policies at the municipal operations level. ● PS-5.7 Storms. Provide access to flood protection resources and services (signage, sandbags, etc.) at designated public facilities before and during extreme weather events. ● PS-5.8 Special Assistance. Ensure that individuals with limited mobility or limited access to transportation have equitable access to safe and comfortable shelter during extreme heat events or other severe weather events. EJ
● PS-5.9 Greenhouse Gas Reductions. Reduce community-wide greenhouse gas emissions by actively supporting regional efforts to reduce greenhouse gases. ● PS-5.10 Monitoring. Monitor climate change-related effects with local, regional, State, and/or Federal partners to provide information on effectiveness of existing infrastructure and programs.
● PS-5.11 Extreme Heat Vulnerabilities. Encourage new developments, major remodels, and redevelopments to address urban heat island issues and reduce urban heat island effects for the proposed project site and adjacent properties. ● PS-5.12 Nature-Based Solutions. Prioritize, when possible, nature-based solutions, such as floodplain reconnection, wetland/creek restoration, urban tree canopy, or cool pavements, to minimize flood, heat, wildfire, and drought risks.

PS-5 Actions
● PS-5a Provide information and resources to the public regarding steps the City is taking to mitigate the impacts of a changing climate.
● PS-5b Implement energy-efficient street lights such as LEDs as funding becomes available.
● PS-5c Consider purchasing only electric or alternative-energy vehicles for the City vehicle fleet, as appropriate, based on the intended use of the vehicle.

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● PS-5d Evaluate the feasibility of newly constructed and/or operated City facilities to meet or exceed the CalGreen Tier 1 (or successor program) standards. ● PS-5e Encourage the use of sustainable and carbon-neutral energy sources in new development.
● PS-5f Explore using renewable energy and clean generation technologies such as solar, wind, biogas, or fuel cells to power City facilities where appropriate. ● PS-5g Implement actions and programs to improve drought preparation and response, especially for the most vulnerable community members.
● PS-5h Provide access to flood protection resources and services (signage, sandbags, etc.) as feasible at designated public facilities during and after extreme weather events. ● PS-5i Encourage the use of sustainable and carbon-neutral energy sources in new development.
● PS-5j Encourage the use of transit and active transportation modes in new developments to help reduce greenhouse gas emissions.
● PS-5k Educate the public about designated cooling centers and other places they can go for shelter and assistance during extreme heat events.

Goal PS-6: A City that is well-prepared for emergency response and disaster management to minimize impacts to people, property, the environment, and essential services.

PS-6 Policies
● PS-6.1 Critical Facilities. Coordinate with service providers to ensure the resilience of critical facilities, lifeline services, and infrastructure, and plan for the use of critical facilities during post-disaster response and recovery.
● PS-6.2 Local Hazard Mitigation Plan. Update Brea’s Local Hazard Mitigation Plan (LHMP) on a regular basis to reflect changing conditions, best practices, regulatory environment, and advancements in knowledge, and to maintain eligibility for public assistance grants.
● PS-6.3 Communication. Maintain proper communication protocols and procedures among emergency services providers; local, State, and Federal government agencies; businesses; schools; utility providers; and other relevant parties to ensure quick and efficient response in the event of an emergency.
● PS-6.4 Education. Prepare the community for comprehensive and efficient emergency response including safe and secure evacuation routes. EJ Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

● PS-6.5 Automatic and Mutual Aid. Continue to participate in automatic and mutual aid agreements with adjacent service providers to ensure efficient and adequate resources, facilities, and support services during and after emergencies. ● PS-6.6 Emergency Evacuation Routes and Access. Work with the Fire Department and Police Department to define minimum standards for evacuation of residential areas, particularly in HFHSZs and VHFHSZs, and to maintain, update, and regularly exercise emergency access, protocols, and evacuation routes to assess their effectiveness under a range of emergency scenarios. If areas with inadequate evacuation routes are identified, develop appropriate mitigation measures, improvement plans, or education programs to ensure safe evacuation.
● PS-6.7 Emergency Shelters. Periodically review emergency shelters to ensure that necessary equipment and supplies are available in case of emergency. ● PS-6.8 Collaboration. Strengthen emergency services preparedness and response by linking emergency services with local hazard mitigation programs and enhancing public education on a regional scale.
● PS-6.9 Institutions. Regularly coordinate with the City’s major institutions, schools, employers, and homeowners’ associations regarding emergency response procedures. ● PS-6.10 Volunteer Service. Continue to support volunteer service programs for emergency preparedness and disaster relief such as the City of Brea Community Emergency Response Team (CERT) training.
● PS-6.11 Warning Systems. Maintain and regularly upgrade a mass communications system to effectively notify people during disasters and emergencies by using current communication technologies.
● PS-6.12 Strategic Readiness. Maintain a proactive, data-driven public safety system through recurring five-year strategic planning that aligns resources, facilities, staffing, and technology with community risk and growth.

PS-6 Actions
● PS-6a Regularly practice implementation of the City’s Emergency Operations Plan and update the plan regularly.
● PS-6b Regularly review County and State emergency response procedures that must be coordinated with City procedures.
● PS-6c Continue to implement the City of Brea’s Local Hazard Mitigation Plan.

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● PS-6d Explore grant programs (e.g., FEMA AFG/SAFER, Cal OES, CAL FIRE prevention) that could assist with implementation of the PS-6 Action items. ● PS-6e Prepare and maintain comprehensive five-year strategic plans for both the Fire and Police Departments, updated on a recurring five-year cycle, with annual progress reporting. Plans shall: (a) assess community risk and service demand; (b) define service level objectives; (c) identify facilities, staffing, apparatus/equipment, technology, and organizational design needs; (d) include a Gap/SWOT analysis; (e) perform interdepartmental stakeholder engagement; (f) develop and deploy a Community Survey; and (g) provide a phased, costed implementation action plan. In preparing the plan, the draft strategic plan shall be presented to the public for feedback prior to adoption of the final strategic plan. Once adopted, the five-year strategic plans shall be updated at least every five years and after any annexations or significant development approvals.

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● PS-6f Prepare and periodically update the following technical studies related to the Fire Department’s five-year plan, which may proceed independently or in combination:
○ Community Risk Assessment / Standards of Cover (CRA/SOC) (consistent with NFPA/CPSE frameworks)
○ Facility Condition & Siting Assessments (including seismic, capacity, and location/coverage analyses)
○ Staffing & Workforce Analysis (including succession and training needs) ○ Apparatus & Equipment Lifecycle Plan (replacement schedules and deployment models)
○ Technology & Communications Plan (CAD/RMS/MDT, alerting, radios, station alerting, data systems)
● PS-6g When evaluating public safety impacts of new developments, the methodology shall consider the following at minimum; however, the City may allow alternate methodology on a case-by-case basis:
○ Service Demand Units (SDUs) estimated by land-use type and intensity ○ Population/employee growth and special risk factors (e.g., WUI, hazardous occupancies, vertical development)
○ Network travel-time isochrones and station coverage impacts relative to SLOs ○ Unit-Hour Utilization (UHU) and workload balancing by company ○ Facility/apparatus/staffing triggers when thresholds are exceeded ● PS-6h Publish and maintain a Public Safety Impact Methodology Manual (administrative document) specifying data sources, formulas, GIS methods, thresholds, and mitigation options; update administratively as best practices and local data evolve. ● PS-6i Adopt public safety Service Level Objectives (SLOs) for both Fire and Police Departments, informed by nationally recognized practices (e.g., NFPA 1710/1720/1225 as applicable) and local risk. SLOs may include turnout, travel and total response time percentiles, inspection cycles, training targets, unit-hour utilization thresholds, and community risk-reduction benchmarks.
● PS-6j The Fire and Police Departments shall provide annual report on the adopted SLO.

Mid-cycle adjustments shall be permitted on as needed basis.

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● PS-6k Require major developments (e.g. Specific Plans, General Plan Amendments, Tentative Tract Maps, large-scale projects, phased projects, etc.) to be phased and/or conditioned so that they do not cause material degradation of adopted response performance, coverage, or unit-hour utilization beyond thresholds specified by Council. ● PS-6l If impacts to public safety are identified for new development, require fair-share contribution to mitigate such impact, using one or more tools, such as, but not limited to, public safety impact fees, development agreements, CFDs/Mello-Roos, in-lieu contributions, land dedication for facilities, or direct provision of facilities/apparatus/technology.
● PS-6m Maintain consistency between the five-year strategic plans, the General Plan, Capital Improvement Program (CIP), Budget, EOP, and LHMP. Updates to LHMP and EOP shall incorporate relevant findings from the Fire five-year strategic plan and CRA/SOC.
● PS-6n Maintain standardized public safety data (CAD/RMS, inspections, training, risk, GIS layers, development pipeline) and publish an annual scorecard tracking SLOs, workload, risk trends, capital status, and development impacts.

Goal PS-7: A community whose residential neighborhoods and sensitive uses are minimally impacted by noise from freeways, motor vehicle traffic, and stationary noise sources.

PS-7 Policies
● PS-7.1 Land Use Decisions. Consider existing and future noise levels when making land use planning decisions and require measures to reduce significant noise impacts to the extent feasible.
● PS-7.2 Sensitive Uses. Locate sensitive facilities such as residential uses, schools, medical facilities, libraries, churches, and convalescent homes away from areas of excessive noise unless proper noise reduction measures are in place. EJ ● PS-7.3 Site Design. Protect noise-sensitive uses from excessive noise levels by incorporating site planning and project design techniques to minimize noise impacts. The use of noise barriers shall be considered after all practical design-related noise measures have been integrated into the project. In cases where sound walls are necessary, designs of such sound walls must consider other project features such as setbacks, changes in alignment, detail, and texture, murals, pedestrian access, and landscaping to be integrated into the project design. EJ

Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

● PS-7.4 Mixed Use Development. Ensure that mixed use structures and projects are designed to minimize transfer of noise and vibration from nonresidential areas to residential areas.
● PS-7.5 Special Events. Specific events which generate noise in excess of local noise standards may be considered on a case-by-case basis when they contribute to the quality of life for the Brea community.
● PS-7.6 Noise Control. Utilize innovative noise abatement, design techniques, and other mitigation strategies – including staggered operating hours, insulation, building setbacks, noise barriers, placement of parking and utility areas, and building orientation – to ensure that noise levels do not exceed the limits in the Brea City Code. ● PS-7.7 Roadway Noise. Encourage nonmotorized transportation alternatives for local trips and the implementation of noise sensitivity measures in the public realm, including traffic-calming road design, lateral separation, natural buffers, and landscaped setbacks to decrease excessive motor vehicle noise along major arterials. ● PS-7.8 Highway Noise. Coordinate with the California Department of Transportation (Caltrans) to achieve maximum noise abatement in the design of new highway projects or improvements, which could include alignment, barriers, lateral separation, or other innovative techniques.
● PS-7.9 Vehicles and Trucks. Monitor and enforce existing speed limits and motor vehicle codes requiring adequate mufflers on all types of vehicles traveling through the City and compliance with designated truck routes.
● PS-7.10 Interjurisdictional Coordination. Coordinate with Orange County and neighboring jurisdictions as necessary to minimize noise conflicts between land uses along the City’s boundaries.
● PS-7.11 Nuisance Noise. Minimize noise nuisances through the Brea City Code.

PS-7 Actions
● PS-7a Update the Brea City Code to ensure that the noise standards are consistent with this General Plan, and to require new residential, mixed use with a residential component, and other noise-sensitive development to be designed to minimize noise exposure for noise-sensitive uses through incorporation of site planning and architectural techniques.

The update shall also include noise standards for residential uses within a mixed use development, which may differ from other adopted residential noise standards. ● PS-7b Review new development projects for compliance with the noise requirements established in this General Plan, including the standards established in Tables PS-1 and Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

PS-2. Where necessary, require new development to mitigate excessive noise through best practices, including building location and orientation, building design features, placement of noise-generating equipment away from sensitive receptors, shielding of noise-generating equipment, placement of noise-tolerant features between noise sources and sensitive receptors, and use of noise-minimizing materials such as rubberized asphalt.
● PS-7c Require acoustical studies for all new discretionary project where appropriate, which have the potential to generate noise impacts or include sensitive uses that would be exposed to noise levels that exceed the standards identified in this General Plan. The studies shall include representative noise measurements, estimates of existing and projected noise levels, and mitigation measures necessary to ensure compliance with this Element.

Economic Development Element
Goal ED-1: A diverse and resilient economic environment that enhances the quality of life for residents, attracts quality employers, and encourages visitors.

ED-1 Policies
● ED-1.1 Land Uses. Maintain and expand the City’s opportunities to support diverse businesses by identifying opportunity sites for residential and commercial development that align with regional market demand.
● ED-1.2 Mixed Use Development. Encourage the development of mixed use projects that incorporate both housing and nonresidential spaces. EJ
● ED-1.3 Diverse Business and Employment. Encourage a broad range of business uses that provide employment at all income levels and that make a positive contribution to the City’s tax base. EJ
● ED-1.4 Local and Regional Events. Work with local and regional business associations and other regional organizations to create, sponsor, and market events to support local businesses.
● ED-1.5 Targeted Business Attraction. Identify and target outreach to expanding local economic opportunities, especially in industries such as, but not limited to, technology services, medical services, and complementary hospitality businesses. ● ED-1.6 Entertainment and Tourism Industry Support. Continue to foster City-initiated programs and collaborative relationships with the regional tourism industry and other partner organizations to promote local and regional tourism.

Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

● ED-1.7 Economic Base Diversification. Explore creative opportunities to diversify the City’s economic base, including through City-led projects and public-private partnerships. ● ED-1.8 Fiscal Sustainability. Encourage the attraction and retention of sales taxgenerating businesses to support long-term fiscal sustainability and maintain high-quality public services.

ED-1 Actions
● ED-1a Develop an Economic Development Strategic Plan within five years. ● ED-1b Periodically conduct a survey of vacant, underdeveloped, and underutilized sites, and engage with property owners regarding business attraction efforts or redevelopment opportunities.
● ED-1c Host or support regional events that broaden the City’s visibility, promote local businesses, and leverage the City’s diverse economic base. ● ED-1d Improve the marketability of opportunity sites through the promotion of Brea’s market advantages.
● ED-1e Provide technical assistance, training, or financial resources to help local businesses plan for, withstand, and quickly recover from economic disruptions, natural disasters, or public health emergencies, where applicable.

Goal ED-2: A local economy that supports existing businesses and attracts high-quality businesses and industries with promising growth and innovation.

ED-2 Policies
● ED-2.1 Entrepreneurship. Educate and support local and regional entrepreneurs in establishing and expanding small and local businesses.
● ED-2.2 Resources. Provide the business community with easily accessible information, both online and in-person, on available resources for growth and development, including those aimed at entrepreneurs and small businesses.
● ED-2.3 Engagement. Communicate regularly with local businesses regarding areas of interest and concerns affecting their ongoing operations. ● ED-2.4 Office Conversions. Encourage the repurposing of office space to fit the needs of current and prospective Brea businesses.
● ED-2.5 Regional Promotion. Support legislation and other efforts to promote Orange County and California as an attractive place to do business.

Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

● ED-2.6 Relocation Assistance. Encourage high-quality businesses, including, but not limited to, the medical and technology services industries, to relocate within Brea.

Facilitate, when appropriate, planning and permitting processes for businesses that are trying to relocate.

ED-2 Actions
● ED-2a Develop and provide user-friendly Development Manuals regarding planning and permitting processes for businesses that are trying to locate to or within Brea. ● ED-2b Incorporate business-friendly policies into customer care training for City staff. ● ED-2c Implement strategies and actions that improve multimodal transportation networks and land use policies that build off existing hospitality and commercial areas to enhance accessibility and economic activity.
● ED-2d Partner with local hospitality employers to strategically attract businesses that will complement existing amenities and serve a range of visitors and residents. ● ED-2e Integrate the business community’s interests into City’s legislative advocacy work. ● ED-2f Participate in meetings between economic development leaders or regional partners to discuss mutually-beneficial, regional economic development opportunities. ● ED-2g Maintain access to listings of significant commercial and industrial vacant properties, buildings, or space in the City, including the key real estate brokers or salesperson involved. Direct potential buyers or tenants of retail, commercial, or industrial space to appropriate brokers.
● ED-2h Provide business recognition efforts through programs that honor Brea businesses. ● ED-2i Collaborate with businesses to increase marketing efforts related to local events, through digital marketing and community engagement and incorporate feedback loops to improve future events.
● ED-2j Maintain strong relationships with the City’s existing local industries, local organizations and regional partners through regular communication, while pursuing business community support actions described herein.
● ED-2k Assist local business expansion through supportive policies and programs, including regulatory assistance, financial support, or mentorship programs.

Goal ED-3: A community that seeks to retain and attract a skilled workforce and provides Brea 2050 Public Hearing Draft General Plan Goals Policies and Actions (April 2026, Version 2)

opportunities for them to both live and work in Brea.

ED-3 Policies
● ED-3.1 Retain Workers. Work to retain a greater share of the current workforce by encouraging the development of housing and retention of high-paying jobs for residents. ● ED-3.2 Marketing Opportunities. Actively pursue marketing opportunities to enhance the City’s business-friendly reputation to attract businesses and improve employee recruitment and retention.
● ED-3.3 Housing Choices. Develop land use policies that facilitate the development of housing affordable to a range of household types and incomes to diversify the local labor force and promote long-term residential stability. EJ
● ED-3.4 Educational Relationships. Develop relationships with local and regional education institutions to ensure workers have the skills and training to succeed in a variety of industries, promote job retention, and grow the local talent pipeline. ● ED-3.5 Educational Opportunities. Provide educational opportunities that align with local business needs to increase economic development resources for existing and prospective business owners in Brea.

ED-3 Actions
● ED-3a Engage with local and regional economic development partners to host regular meetings that grant small businesses, entrepreneurs, and potential investors opportunities to connect, network, and collaborate.
● ED-3b Recognize businesses that prioritize employee retention and well-being. ● ED-3c Convene with major employers to solicit guidance on how the City can support partnerships and develop policies to create a strong workforce pipeline and identify specific workforce needs.
● ED-3d Utilize the provisions of Chapter 17 ("Economic Development") of the Brea City Code to conduct marketing, business attraction, and business retention programs.

Attachment C. Attachments to Letter O2 from Hills for Everyone This page intentionally left blank.

Exhibit A
1 Kristi Bascom
From: Brea2050 <[email protected]>
Sent: Wednesday, September 24, 2025 8:46 PM
To: Kristi Bascom
Cc: [email protected]; Schlotterbeck, Claire; Edward T. Schexnayder; Brea2050 Subject: RE: CEQA Comments for Brea 2050: Focused GPU and BCSP Hello,
This is to acknowledge the receipt of the NOP comments.

Thank you.

Sincerely,
Community Development | Planning
P: 714-990-7674 | E: [email protected] | W: www.brea.generalplan.org City of Brea | 1 Civic Center Circle | Brea, California 92821 The City Hall is closed alternating Fridays.

Please click 2025 Calendar for City Service Hours/Alternate Fridays Closed.

From: Kristi Bascom <[email protected]>
Sent: Wednesday, September 24, 2025 2:06 PM
To: Brea2050 <[email protected]>
Cc: [email protected]; Schlotterbeck, Claire <[email protected]>; Edward T. Schexnayder <[email protected]>
Subject: CEQA Comments for Brea 2050: Focused GPU and BCSP Dear City of Brea Planning StaƯ,
On behalf of our client, Hills For Everyone, we submit the attached comment letter on the Notice of Preparation (NOP) for the forthcoming EIR on the City of Brea’s Focused General Plan Update (GPU) and Brea Core Specific Plan (BCSP).
2 Please confirm that this email has been received and inform me directly if you have any trouble accessing the attached PDF.

Kind regards,
Kristi Bascom
Kristi Bascom, AICP
Urban Planner
Shute, Mihaly & Weinberger LLP
396 Hayes Street
San Francisco, CA 94102-4421
o: 415/552-7272 x 202 c: 925/872-6327
www.smwlaw.com | A San Francisco Green Business
Exhibit B
Maintaining Ecological Connectivity
Across the “Missing Middle”
of the
Puente-Chino Hills Wildlife Corridor
Final Report
July 2005
The Conservation Biology Institute provides scientific expertise to support conservation and recovery of biological diversity in its natural state through applied research, education, planning, and community service.

Maintaining Ecological Connectivity
Across the “Missing Middle”
of the
Puente-Chino Hills Wildlife Corridor
Final Report
Prepared by:

Wayne D. Spencer, Ph.D.
815 Madison Avenue
San Diego, CA 92116
Prepared for:

Resources Legacy Fund Foundation
555 Capitol Mall, Suite 650
Sacramento, CA 95814
July 2005
Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute ii July 2005
Table of Contents
Page
Acknowledgements ................................................................................................................ iv Executive Summary.................................................................................................................v Methods................................................................................................................................v Results............................................................................................................................... vii Discussion.......................................................................................................................... ix Conclusions and Recommendations ....................................................................................x Introduction..............................................................................................................................1 Report Objectives.................................................................................................................2 Study Area ................................................................................................................................4 Biogeography.......................................................................................................................4 Previous Studies...................................................................................................................4 Methods...................................................................................................................................10 Reconnaissance..................................................................................................................10 Target Species....................................................................................................................11 Defining Geographic Units, Barriers, and Filters ..............................................................14 Analyses — Assessing Existing and Future Functionality................................................18 Results .....................................................................................................................................20 Functionality of Geographic Units.....................................................................................20 Summary of Overall Corridor Function.............................................................................31 Future Corridor Functions..................................................................................................35 Discussion................................................................................................................................40 Functions and Benefits of Wildlife Corridors....................................................................40 Assessing Connectivity Pros and Cons..............................................................................40 Mitigating Road Effects.....................................................................................................43 Conclusions and Recommendations.....................................................................................45 Conservation and Restoration Priorities for the Missing Middle ......................................45 References Cited.....................................................................................................................49 Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute iii July 2005
Page
Maps
Map 1. Study area showing the Missing Middle of the Puente-Chino Hills Wildlife Corridor................................................................................................3 Map 2. Geographic units of the Puente-Chino Hills Wildlife Corridor……………... 15 Map 3. Conservation and restoration priorities in the vicinity of Missing Middle...... 46 Figures
Figure 1. The Puente-Chino range of hills juts into the heavily urbanized Los Angeles Basin from the tip of the Santa Ana Mountains range……………………...… 1 Figure 2. View northwest across Coal Canyon Wildlife Underpass…......................... 23 Figure 3. View northeast across Tonner Bridge and Highway 57…………………….. 25 Figure 4. View northwest across Segment 3 and Harbor Boulevard to Segment 4, indicating general trends in wildlife movements……………………………. 27 Figure 5. Conceptual development plan for the Shell-Aera Master Planned Community………………………………………………………………… 35
Figure 6. Aerial photograph showing City of Industry’s proposed Tres Hermanos reservoir and new road in Tonner Canyon…………………………………... 37 Photos
Photo 1. View east under the Tonner Bridge…………………………………………. 26 Photo 2. View southeast across the Harbor Boulevard “deathtrap”…………………. 28 Tables
Table 1. Summary of previous studies of wildlife populations and movements in the Puente-Chino Hills study area………………………………………………... 5
Table 2. Characteristics of geographic units comprising the Puente-Chino Hills Wildlife Corridor……………………………………………………………. 21
Table 3. Characteristics of roads crossing the Puente-Chino Hills Wildlife Corridor... 22 Table 4. Functional classification of geographic units for supporting target species populations and movements…………………………………………………. 33
Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute iv July 2005
Acknowledgements
Conservation Biology Institute (CBI) thanks the following individuals and organizations for support and contributions to this report. Financial support was provided by Resources Legacy Fund Foundation, with special thanks to Maureen Rose and Ed Hastey. Rick Rayburn (California State Parks) was responsible for involving CBI in this important project and provided early guidance on its goals. Claire Schlotterbeck (Hills For Everyone) provided essential information, advice, contact information, and inspiration, and Melanie Schlotterbeck (The Trust for Public Land) provided GIS data, photographs, advice, information, contacts and other valuable input. Dan Wooldridge (Waters and Faubel) provided copies of various reports and plans reviewed in this report. Andrea Gullo and Amy Henderson (Puente Hills Landfill Native Habitat Preservation Authority) also provided data, reports, and other useful information. Geary Hund, Claire Schlotterbeck, Melanie Schlotterbeck, and Amy Henderson reviewed a draft of this report and offered valuable corrections and clarifications to the contents. The following CBI employees assisted in preparing this report: Heather Rustigian, with oversight from Jim Strittholt, prepared GIS maps and calculations; John Bergquist provided Keyhole screen captures used as illustrations; and Mike White and Jerre Stallcup reviewed and helped produce the report.

Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute v July 2005
Executive Summary
The Puente-Chino Hills Wildlife Corridor is a peninsula of mostly undeveloped hills jutting about 42 km (26 miles) from the Santa Ana Mountains into the heart of the densely urbanized Los Angeles Basin. Intense public interest in conserving open space here has created a series of reserves and parks along most of the corridor’s length, but significant gaps in protection remain.

These natural habitat areas support a surprising diversity of native wildlife, from mountain lions and mule deer to walnut groves, roadrunners, and horned lizards. But maintaining this diversity of life requires maintaining functional connections along the entire length of the corridor, so that wildlife can move between reserves—from one end of the hills to the other.

Already the corridor is fragmented by development and crossed by numerous busy roads, which create hazards and in some cases barriers to wildlife movement. Proposed developments threaten to further degrade or even sever the movement corridor, especially within its so-called “Missing Middle.” This mid-section of the corridor system, stretching from Tonner Canyon on the east to Harbor Boulevard on the west, includes several large properties proposed for new housing, roads, golf courses, and reservoirs. Such developments would reduce habitat area and the capacity to support area-dependent species and, if poorly designed, could block wildlife movement through the corridor.

This report builds on an impressive array of previous ecological and wildlife movement studies in the Puente-Chino Hills, as well as the general literature on wildlife movement corridors as it applies to this unique peninsula of wildness. It supplements the existing information with an analysis of gaps in protection—with special focus on the vulnerable Missing Middle—and recommends conservation and management actions to prevent further loss of ecological connectivity and retain native species.

Methods
I performed a meta-analysis of corridor function using existing scientific information on the distribution and movement patterns of wildlife species in the study area, as supplemented by field reconnaissance and examination of aerial and satellite imagery. Following the lead of previous researchers, I segmented the range of hills into nine geographic units by roads and other breaks in habitat contiguity. From southeast to northwest these are:
• A biological “core” area (defined below), represented by the Santa Ana Mountains; • Seven segments of the functional Puente-Chino Hills Wildlife Corridor (from southeast to northwest: 1-Chino, 2-Carbon-Tonner, 3-Shell-Aera, 4-Powder-Schabarum, 5-San Miguel, 6-East Whittier, 7-West Whittier); and
• One isolated patch off the tip of the range of hills (Whittier Narrows), which is effectively disconnected from the functional corridor segments by major roads and urban barriers.

Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute vi July 2005
The Missing Middle consists of the western portion of Segment 2 (including the large and biologically diverse Tonner Canyon) and all of Segment 3 (Shell-Aera property and adjacent lands between Highway 57 and Harbor Boulevard). The eastern portion of Segment 2 (between Tonner and Carbon Canyons) is largely conserved already, but Tonner Canyon and Shell-Aera are unprotected and threatened by development projects.

Each of the nine geographic units was initially characterized for how it appears to function in supporting populations of target species, including mountain lion, mule deer, bobcat, coyote, coast horned lizard, and greater roadrunner, as well as in the richness of its reptile and amphibian community. The following coarse-scale definitions apply to these units:
• Core areas must be larger than 2,000 sq. km and capable of supporting a population of 20 adult mountain lions (the most area-dependent target species). Due to large size and relatively low “edge effects,” a core area will support the greatest diversity of species and should support populations of all target species. The Santa Ana Mountains are the only core in the study area. This core serves as a source for mountain lions and other species to enter the corridor system.
• Subcores are smaller (but at least 60 sq. km) and capable of supporting a population of bobcats, the second-most area-dependent target species. Subcores can sustain populations of most target species and have moderate to high species diversity. Corridor Segment 1 (Chino Hills between Highways 91 and 142) is the only subcore, although Segment 2 appears to function as an extension of this subcore, as discussed below. • Patches are smaller than 60 sq. km, but may support small numbers of bobcats and significant populations of other target species. Patches may also provide significant livein or move-through habitat for mountain lions and bobcats, whose home ranges may cover multiple geographic units. Most segments in the corridor system are patches, but they vary greatly in size (from about 1.5 to 44.3 sq. km), vegetation composition, isolation by roads, and ability to support target species.

The roads delimiting these segments were next characterized for their effects on target species movements—as barriers, semi-permeable “filters,” or highly permeable filters. Based on the scientific literature and field reconnaissance, each road was assessed for how easily target species can cross it, the availability and effectiveness of crossing structures (e.g., bridges and underpasses), and relative frequency of roadkill. Roads considered highly permeable to wildlife movement allow adjacent segments to function as one larger segment, such that two areas originally classified as separate patches may effectively serve as one larger patch (summing the area of adjacent units), or even a subcore, for certain target species.

I assigned each newly defined unit, or composite unit, a function relative to supporting individuals or populations of each target species based on unit size, habitat composition, and other factors, as follows:

Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute vii July 2005
• Population — capable of supporting a breeding population of at least 20 adults and potentially serving as a source of individuals that disperse into other units. • Subpopulation — capable of supporting at least two but less than 20 breeding individuals.

Subpopulations may exchange individuals with other areas within a larger metapopulation (a set of partially isolated populations linked by occasional dispersal) and may provide individuals to recolonize habitat patches in case of local extirpation. • Home Range Part — incapable of supporting at least two breeding individuals on its own, but may provide live-in habitat (e.g., foraging or resting cover) and form a part of one or more individuals’ home range(s).
• Move-through — not contributing significant live-in habitat for a species as part of a functional home range, but capable of accommodating movements between more substantial units within a home range, or potentially used for dispersal between other habitat units.

This system for characterizing geographic units and movement impediments was used to assess how the overall corridor system functions to support target species, and how these functions might change with potential development scenarios, such as new roads or housing that could add movement barriers or reduce wildlife carrying capacity in corridor segments.

Results
Existing Corridor Function
The Puente-Chino Hills Wildlife Corridor appears functional for at least larger mammals and birds, although tenuously so in the Missing Middle (due to several barrier or near barrier roads) and across smaller Segments 4 and 5 (due to their small size, strong edge effects, and high human and pet activity). Essentially all roads in the study area are considered barriers or at least strong filters to movements by many reptiles, amphibians, and small mammals; however, most birds and larger mammals currently can move between all segments either at-grade (with mortality risks) or via critical road-crossing structures. Despite many crossing constraints through the corridor, especially in and just west of the Missing Middle, target species are confirmed or highly likely to occur in all seven Puente-Chino Hills corridor segments, except for coast horned lizard, which may already be absent (or will disappear in the future) west of Highway 57.

Individual mountain lions are capable of traversing the length of the corridor, albeit at some risk of roadkill, and one or more lions still hunt as far west as the western Puente Hills (known locally as the Whittier Hills). Most other target species (e.g., bobcats, roadrunners) appear to persist throughout the corridor as metapopulations that are connected genetically and demographically by at least occasional dispersal between geographic units.

Carbon Canyon Road (between Segments 1 and 2) and Turnbull Canyon Road (between Segments 6 and 7) are considered highly permeable to at least larger mammals and birds, so I Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute viii July 2005
merged Segments 1 and 2 to form a larger Chino-Tonner subcore, and I merged Segments 6 and 7 to form a larger Whittier Hills patch. The most critical road-crossing structures are the Coal Canyon Wildlife Underpass (connecting the Santa Ana Mountains Core to the Chino Hills under Highway 91); a box culvert under Carbon Canyon Road known to be used by bobcat and other species; the Tonner Canyon Bridge on Highway 57 (the only viable crossing beneath this busy freeway for deer, mountain lion, bobcat, and other species); and the Colima Service Tunnel (used by bobcat, deer, coyote, and other species to cross under Colima Road between San Miguel Canyon and the Whittier Hills). In addition, a new wildlife tunnel is being built under Harbor Boulevard (between Segments 3 and 4) at a location well-documented as a roadkill “death trap.” There appears to be a gradient of declining amphibian and reptile diversity and evenness moving west from the Chino Hills, probably due to increasing edge effects coupled with increasing distance and number of barriers and filters that must be crossed the farther west one moves from source habitats in the east. A similar gradient may exist for other taxa, such as small mammals, that are similarly limited in their dispersal abilities.

Given the length of the corridor relative to species movement abilities, the capacity of corridor segments to support many species depends both on
• The potential for individual movement between each set of adjoining segments (a function of roads and road-crossings), and
• Having sufficient live-in habitat along the way to support populations or subpopulations that contribute dispersing individuals.

The greater a segment’s distance from units supporting populations or subpopulations of a species, the lower the probability that the segment can continue supporting a species. If the distance between occupied segments becomes too great, or if barriers prevent inter-segment movement, local extinctions are inevitable in the isolated segments. Thus, any reduction in the capacity of segments to support populations or subpopulations increases the probability of local extinctions in that segment, as well as in all other “downstream” segments to the west.

Habitats in the Missing Middle are critical to maintaining overall corridor function. The Tonner Canyon area serves as an extension of the large Chino-Tonner subcore, with significant live-in habitat that can contribute dispersing animals to move into other segments. Likewise, Segment 3 (Shell-Aera) presumably supports significant numbers of target species that disperse (currently at some risk) across Harbor Boulevard into Powder Canyon (Segment 4) and beyond.

Future Scenarios
I assessed the likely effects of several proposed development projects in the Missing Middle on species persistence through the corridor system. This qualitative assessment uses the conceptual model developed above, based on how projects might affect the capacity of geographic units to support populations or individuals and the ability of individuals to cross between units. The projects include a new residential community, a series of reservoirs, and a major new road.

Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute ix July 2005
All three proposed developments have the potential to extirpate target species from large portions of the Puente-Chino Hills Wildlife Corridor. By impeding species movements or metapopulation dynamics, a project’s impacts on species persistence may extend far beyond project boundaries, potentially rippling through the range of hills to eliminate wildlife populations as far west as the Whittier Hills (10-12 km west of the Missing Middle). The proposed Shell-Aera Master Planned Community would seriously degrade the ability of Segment 3, and all segments farther west, to support target species, especially mountain lion and bobcat.

This would have cascading effects on flora and fauna in all segments from this point west.

A plan by the City of Industry to build three water reservoirs in Tonner Canyon could also have substantial adverse impacts on corridor function. Although a reservoir or other development in upper reaches of Tonner Canyon might not greatly affect corridor function, any development in middle and especially lower Tonner Canyon could have severe impacts on corridor function, especially if wildlife use of the Tonner Canyon Bridge (to cross Highway 57) is reduced. Any development that blocks access through the bridge area would make Highway 57 a complete barrier to many species and would likely lead to wildlife extirpations in segments farther west.

At the very least, creation of these reservoirs would reduce the size of the Chino-Tonner subcore and its capacity as a source of animals that disperse into the rest of the corridor system.

Finally, plans by the City of Industry to build a new road running the length of Tonner Canyon could split the Chino-Tonner subcore in two, potentially isolating about 21.2 sq. km of habitat from this currently large and contiguous source habitat. The road would probably require major cut and fill to construct and could render disfunctional the critical Tonner Bridge wildlife undercrossing. This would almost surely result in the rapid loss of mountain lion and bobcat from more westerly segments, with cascading effects through the ecological community. Deer and other species would also likely disappear from westerly segments over a longer time period.

A full impact analysis for any of these proposed projects should address cumulative impacts on wildlife populations and movements through the corridor. Among these cumulative impacts would be inducement of further development, such as additional residential, commercial, or industrial development along the road. Increases in traffic and roadkill should also be analyzed and mitigated for. Any combination of two or more of these projects, even if well designed, would likely render the Puente-Chino Hills Wildlife Corridor non-functional west of Chino Hills State Park, regardless of mitigation.

Discussion
The scientific literature on the functions and values of wildlife corridors is huge and growing.

Movement corridors connecting reserves or larger “core areas” of habitat have been documented to counter many adverse effects of isolation by fragmentation on species and ecological processes. Some critics have argued that there are costs as well as benefits to conserving corridors and that, under certain circumstances, creating or maintaining corridors could harm some species or communities. However, the overwhelming weight of scientific evidence is that maintaining connectivity is beneficial, especially for those species and ecological communities Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute x July 2005
for which connectivity “is the natural state of things.” Most arguments against corridors boil down to nothing more than cautions against viewing them as conservation panaceas.

Nevertheless, I reviewed the following arguments made against corridor conservation as they apply to the Puente-Chino Hills Wildlife Corridor:

1. Corridors may serve as conduits for the spread of deleterious species;

2. Corridors may spread detrimental processes, such as wildfire or disease, among reserve areas;

3. Corridors may facilitate movements by highly mobile and adaptable animals (like coyotes), but may not help more sedentary or at-risk species;

4. Corridors could attract wildlife into edge-affected habitats with high mortality rates; and

5. Corridor conservation may be more expensive or less beneficial than other options, such as increasing the size or management of core reserves.

Critical review of these concerns for the Puente-Chino Hills Wildlife Corridor finds them irrelevant or insignificant in this case; at least, the biodiversity benefits of conserving the corridor far outweigh any potential for harm.

Mitigating the adverse effects of roads, including barrier effects and increased mortality, is essential to maintaining corridor functions. The scientific literature on effective mitigation actions, especially wildlife road-crossing structures, is also large and growing, with many success stories. The main types of structures, from most to least effective, are vegetated landbridges (wildlife overpasses), bridges, underpasses, and culverts. Vegetated overpasses are quieter than underpasses, maintain ambient conditions, seem less intimidating for some species than dark tunnels, and have proven highly successful in the U.S., Canada, and Europe for a wide variety of wildlife species. Bridges are also highly effective, especially if wide and open with natural vegetation growing beneath, such as under the Tonner Bridge. Culverts and other tunnellike structures can be effective for some species, but only very large culverts (such as box culverts and equestrian tunnels) are effective for larger mammals. Earthen flooring is preferable to concrete or metal. Regardless of crossing type, wildlife fencing is crucial for keeping animals off the road and for funneling them toward the crossing structure. Vegetative cover near the entrances also increases wildlife use of crossing structures.

Conclusions and Recommendations
Given the huge investment already made to maintain the Puente-Chino Hills Wildlife Corridor, additional conservation investment in the Missing Middle seems not only prudent, but essential if society believes the continued presence of deer, bobcats, roadrunners, and other wildlife is desirable in this unique peninsula of wild in a sea of development. My recommendations for how to do this are largely concordant with previous recommendations by other biologists.

I recommend conserving all of Segment 3 (the Shell-Aera property) and at least the middle and lower portions of Tonner Canyon, including prohibiting any new road or other development that Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute xi July 2005
would fragment this critical habitat block or degrade in any way the utility of the Tonner Bridge as a wildlife underpass. I also emphasize the following recommendations for improving roadcrossing structures and reducing roadkill.

A. Add wildlife fencing on either side of Carbon Canyon Road to reduce roadkill and encourage wildlife to use existing culverts, especially the concrete box culvert near the entrance to Chino Hills State Park. Add another wildlife crossing structure (bridge or vegetated over-crossing), designed to accommodate all large mammals, as mitigation for any future road upgrades.

B. Prohibit any development that would increase traffic under the Tonner Bridge or add any new impediments (structures, lights, noise, etc.) to the vicinity of the bridge. Restore riparian vegetation along Tonner Creek, where degraded by oil development activities.

Fence along Highway 57 if monitoring suggests road mortality is high.

C. Secure rights to install wildlife fencing along both sides of Harbor Boulevard to reduce roadkill and ensure maximum utility of the wildlife tunnel being built here. Plant screening vegetation on either side of the tunnel to provide cover to wildlife approaching the entrances.

D. Secure remaining “at-risk” parcels in the narrow, constricted portion of the corridor between Powder Canyon and Hacienda Boulevard. Enlarge or otherwise improve the existing equestrian tunnel under Hacienda Boulevard to enhance its use by wildlife, including adding screening vegetation on the western end. Add wing fencing on either side of the tunnel to help funnel wildlife to it. Do not fence extensively along Hacienda Boulevard, unless coupled with new crossing structures, because most large mammals currently cross at-grade. Consider building a wildlife overpass (a vegetated wildlife bridge) over Hacienda Boulevard, taking advantage of steep slopes rising up from either side of the road, as mitigation for any future road improvements that would increase traffic volume or speed.

E. Maintain and improve the Colima Service Tunnel as a critical wildlife underpass. Add fencing or screening vegetation if necessary, based on further site-specific inspection or monitoring. Limit actions that would increase disturbance in the vicinity of the Service Tunnel from sunset to sunrise, such as artificial lighting or nighttime traffic or recreational uses through the tunnel.

Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute 1 July 2005
Figure 1. The Puente-Chino range of hills juts into the heavily urbanized Los Angeles Basin from the tip of the Santa Ana Mountains range (Keyhole screenshot).

Introduction
The Chino and Puente Hills form a peninsula of wild uplands that jut from the Santa Ana Mountains into the heart of one of the largest unbroken urban areas in North America (Figure 1).

Created by shifting Earth plates, this peninsula of wild in a sea of development supports a surprising diversity of native wildlife. Mountain lions still hunt mule deer in the area’s diverse mosaic of grasslands, chaparral, coastal sage, and oak and walnut woodlands; roadrunners, California gnatcatchers, northern harriers, and other birds in decline throughout Southern California still persist here; as does a remarkably rich reptile and amphibian fauna.

Maintaining this diversity, and the web of healthy ecological interactions it represents, presumably requires keeping this range of hills fully connected by wild habitats along its 42 km (26 mi) length. Severing connections or blocking movement along this corridor with roads or housing projects threatens to extirpate species from this urban reserve system and degrade ecological health throughout this range of hills—thus eliminating a remarkable ecological classroom within easy reach of millions of people craving a connection with nature.

Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute 2 July 2005
This loss would be doubly unfortunate given the tremendous public investment already made to conserve and restore biological open space and unfettered wildlife movement through this range of hills—from the Coal Canyon wildlife underpass at Highway 91, through Chino Hills State Park, Powder Canyon, Schabarum Park, and other private and public open space dedications to the western end of the Puente Hills (known locally as the Whittier Hills1). According to the California Department of Parks and Recreation, nearly a quarter billion dollars have already been expended or committed to acquiring and restoring natural open space in the Puente-Chino Hills Wildlife Corridor (http://hillsforeveryone.org/state_investment_table.htm). But the benefits of these existing investments is severely threatened by proposed development projects— including new roads, housing developments, golf courses, and reservoirs.

These threats are most urgent in the so-called “Missing Middle” of the corridor—from Tonner Canyon on the east (mostly owned by the City of Industry) to Harbor Boulevard on the west (Map 1). No major reserves are yet established in this broad midsection of the Puente-Chino Hills, and connectivity is threatened by a major new housing development, a proposed road, and a series of new dams and reservoirs that would flood Tonner Canyon. Should one or more of these projects sever functional connectivity, reserves farther west (e.g., Habitat Authority Wilderness Preserve, Powder Canyon, and Schabarum Regional Park, among others) could lose key species and suffer further ecological degradation.

This report reviews available scientific evidence on wildlife movement corridors, reserve design, and local biological resources to define conservation priorities for maintaining connectivity from one end of the corridor to the other. It focuses on the Missing Middle, because this portion is least protected and is at most immediate risk of further degradation. The purpose of this analysis is to identify (a) those portions of the Missing Middle whose conservation would most contribute to continued wildlife movement and ecosystem health throughout the corridor system, and (b) remedial actions that would most improve the situation for native wildlife—such as retrofitting existing roads with wildlife crossing structures to reduce roadkill and improve movement opportunities.

Report Objectives
• Synthesize the science of wildlife movement corridors as it pertains to the Puente-Chino Hills Wildlife Corridor.
• Analyze existing conditions and potential future conditions for the persistence and movement of wildlife populations in the corridor system. • Recommend conservation and management priorities to sustain and improve connectivity through the Missing Middle and hence the greater Puente-Chino Hills Wildlife Corridor.

1 Although “Whittier Hills” is not an official geographic name recognized by the U.S. Geological Survey, the western portion of the Puente Hills is known locally as the Whittier Hills, and previous researchers have used this place name. I therefore also use Whittier Hills to refer to the hills west of Colima Boulevard.

Conservation Biology Institute 3 July 2005
Map 1. Study area showing the Missing Middle of the Puente-Chino Hills Wildlife Corridor.

Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute 4 July 2005
Study Area
This study considers two nested study areas (Map 1): the entire Puente Hills-Chino Hills Wildlife Corridor, extending about 42 km from the Santa Ana Mountains to the San Gabriel River, and the so-called “Missing Middle” of this larger landscape. The Missing Middle is that section of the Puente-Chino Hills Wildlife Corridor from Harbor Boulevard on the west to and including Tonner Canyon on the east. The Missing Middle is largely unconserved and is threatened by a variety of development projects.

Biogeography
The Puente-Chino Hills are the northernmost extension of the Peninsular Mountain Range, which begins in Baja California, Mexico. They are a topographic expression of the 500-km-long Whittier-Elsinore fault system, pushed up between the Whittier and Chino sections of this major slip-shear fault system. The geologically dramatic origins of the hills also contribute to their relatively undeveloped status, because steep slopes, earthquakes, landslides, tar pits, and active and former oil wells have tended to limit development, at least until recently.

The hills rise from the flat Los Angeles Basin, at less than 100 m (300 ft) elevation, to over 540 m (nearly 1,800 ft) at San Juan Hill. The regional climate is mild and Mediterranean, which contributes to the high diversity of species in coastal Southern California. Vegetation in the hills is a mosaic of open grasslands (which have been affected by grazing over the years), coastal sage scrub, chaparral, oak woodlands, riparian scrub, riparian woodlands, and rare California black walnut woodlands—a grossly under-protected resource that could be considered an “endangered habitat.” These communities support flora and fauna relatively typical of the biodiversity in Southern California—which is remarkable given that the hills are entirely surrounded by the largest urbanized area in the U.S.

Previous Studies
The Puente-Chino Hills represent one of the most closely scrutinized and intensively researched wildlife movement corridors in Southern California, if not North America. Its existence and importance are well appreciated by the local populace, with 53% of local residents having “heard of the wildlife corridor in the Puente Chino Hills area” and 83% in favor of maintaining the corridor (51% “strongly” supported this) (Decision Research 2003). The area’s flora, fauna, and ecological functions are well studied, with a number of intensive studies of wildlife distributions and movements covering all or substantial portions of the area (Table 1). In 1994 an entire scientific conference was focused on the biological functions and values of this unique range of hills (Natural Resources in the Puente Hills-Chino Hills Corridor: Implications for Land Use and Planning. A symposium at Whittier College, March 18-19, 1994)2 .

2 Abstracts of papers presented at this conference can be found at http://www.hillsforeveryone.org/PDF_Files/whittier_college_symposium.pdf.

Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute 5 July 2005 Table 1. Summary of previous studies of wildlife populations and movements in the Puente-Chino Hills study area. Reference Target Species Major Focus Study Area Methods Relevant Results Recommendations Robertson et al. 1995 Large mammals
Assess likely movement routes and constraints.

Entire PuenteChino Hills Wildilfe Corridor from the Santa Ana River to the San Gabriel River.

Field reconnaissance, walking the length of the corridor to assess likely movement routes and constraints. Incidental observations of wildlife sign and roadkill.

At least one pathway without complete obstruction existed for large mammals, from the Santa Ana River to the Whittier Hills, in 1994-95, but with several significant constraints. The most critical impediment was Harbor Blvd. and adjacent development. Movement across Interstate 605 to the San Gabriel River (Whittier Narrows Recreation Area) considered “highly improbable.” Conserve land to connect existing reserves (especially in the middle portions of the Corridor); restore native vegetation; retrofit undercrossings at problem roads, especially Harbor Blvd., with tunnels or bridges to reduce roadkill and improve connectivity for large mammals.

Noss et al. 1997
All vertebrate wildlife
Assess importance of Coal Canyon linkage to maintaining viable species populations in the Santa Ana Mountains and Puente-Chino Hills.

Entire PuenteChino Hills Wildlife Corridor and Santa Ana Mountains.

Literature review, field reconnaissance, and analysis of which species’ populations were likely to benefit from protecting and improving the Coal Canyon linkage and underpass.

Coal Canyon is the last viable linkage between the Chino Hills and Santa Ana Mountains. At least 21 vertebrate species have populations <500 individuals in the Puente-Chino Hills, and at least four of these have <50 breeding adults. Risks of extirpation from the hills would increase for all these species in the absence of the Coal Canyon corridor. The corridor also benefits species in the Santa Ana Mountains, especially the mountain lion and several grassland species. Mountain lion and bobcat would likely be the first species adversely affected by loss of the corridor.

Protect and restore a functional undercrossing at the Coal Canyon interchange with Highway 91. Remove pavement and restore natural soils, vegetation, and drainage through the undercrossing, and install wildlife fencing to funnel wildlife off the highway and through the underpass.

Puente-Chino “Missing Middle” Analysis
Table 1. Continued. Conservation Biology Institute 6 July 2005 Reference Target Species Major Focus Study Area Methods Relevant Results Recommendations Haas and Crooks 1999, Haas 2000, Haas and Turschak 2002 Large and mediumbodied mammals
How landscape variables and underpass characteristics affect the distribution and relative abundance of target species in the study area, and the frequency of underpass usage by each species.

Entire PuenteChino Hills Wildlife Corridor, from Santa Ana River to Whittier Hills.

Field methods: scat transects, remote-triggered camera stations, and baited track stations. Statistical analyses:

Correlated probability and frequency of species use with landscape variables (e.g., corridor width, % wild) and underpass characteristics.

Bobcat and long-tailed weasel were negatively associated with habitat fragmentation. Fragmentation was negatively associated with probability of underpass usage by coyote, bobcat, and long-tailed weasel, and negatively associated with the frequency of use by bobcat. Underpass dimensions were important in determining probability of use by deer and gray fox, and with frequency of use in coyote, gray fox, deer, and domestic cat, with more open underpasses used most. The amount of natural cover surrounding the underpass entrance was important for bobcat. Fencing and roadway dividers were most effective on coyote use of underpasses. Overall, the probability of an underpass being used depends primarily on landscape characteristics,
while its frequency of use depends primarily on underpass dimensions.

Bobcats are an excellent target species for conservation in the study area. Habitat acquisition and restoration should be concentrated in the narrowest portion of the corridor and at chokepoints along roadways. Existing underpasses should be surrounded by natural cover and use fencing to direct wildlife under the roadway. Future underpasses should be large and situated as far from residential areas as possible.

Puente-Chino “Missing Middle” Analysis
Table 1. Continued. Conservation Biology Institute 7 July 2005 Reference Target Species Major Focus Study Area Methods Relevant Results Recommendations Cooper 2000 Breeding birds Determine distribution of breeding land birds to identify priority conservation areas.

Entire PuenteChino Hills Wildlife Corridor, from Santa Ana River to Whittier Hills.

Point counts and walking transects to determine presence/absence.

California gnatcatcher, cactus wren, and other rare or declining species documented in diverse locations. Greater roadrunner widespread but not common; most commonly observed in middle portions of the Corridor. California quail found throughout study area except smallest fragments. Burrowing owl apparently extirpated from the study area during the 1990s. Several areas of high-quality habitats supporting diverse avifauna identified.

Conserve three priority areas based on size, threats, and support of declining species: (a) coastal sage scrub in northern Brea and Yorba Linda (southern portion of Missing Middle); (b) extensive grassland and savannah south of Rowland Heights (northern portion of Missing Middle); (c) grasslands of upper Tonner Canyon (northeastern portion of Missing Middle).

PCR et al. 2000
General wildlife
Analyze the Puente Hills area as a Significant Ecological Area (SEA) recognized by the County of Los Angeles.

That portion of the study area within Los Angeles County, from the Whittier Narrows to Tonner Canyon.

No original field studies; review and analysis of existing information.

The area meets several designation criteria as an SEA, including that it is regionally important to many resident and migrating species, especially large mammals, wintering raptors, and songbirds, in large part due to regional connectivity.

Retain connectivity and linkage values between major canyons of the SEA, and especially at choke points and major road crossings.

Puente-Chino “Missing Middle” Analysis
Table 1. Continued. Conservation Biology Institute 8 July 2005 Reference Target Species Major Focus Study Area Methods Relevant Results Recommendations Lyren 2001 Coyotes and bobcats
Home range and movement characteristics, roadkill, and underpass use by bobcats and coyotes.

Primarily along SR 71 and adjoining areas occupied
by telemetered
animals.

Radio telemetry (29 coyotes, 4 bobcats); roadkill surveys along SR-71.

Home ranges of about half of all telemetered animals overlapped SR71, indicating frequent road crossing by individuals. Most animals crossing
the road were documented using underpasses; coyotes used underpasses more than bobcats. Coyote use of underpasses seemed suppressed by traffic volume. No bobcats were found road-killed; coyotes frequently were road-killed, with concentrations where no wildlife fencing was present along road.

Wildlife fencing should be used to funnel wildlife to underpasses.

Schlotterbeck 2001
Large and mediumbodied mammals; reptiles and amphibians.

Assemble existing data from Haas and Crooks 1999 and Case and Fisher 1998 into a GIS database.

Entire PuenteChino Hills Wildlife Corridor, from Santa Ana River to Whittier Hills.

No original field studies. Interviews with previous researchers and compilation and analysis of existing field data.

See entries for Haas and Crooks (1999) and Case and Fisher (1998) below. A comprehensive GIS database of their results was made available for research and monitoring.

Conservation and restoration of numerous lands, and proper management of these lands, is essential to stave off further species losses and ecological collapse in the Puente and Chino Hills.

Puente-Chino “Missing Middle” Analysis
Table 1. Continued. Conservation Biology Institute 9 July 2005 Reference Target Species Major Focus Study Area Methods Relevant Results Recommendations Haas et al. 2002, Case and Fisher 1998 Reptiles and amphibians
Determine distribution and diversity of herpetofauna; identify management needs to maintain diversity.

Scattered locales across the PuenteChino Hills Wildlife Corridor, from Chino Hills State Park to Whittier Hills.

Field methods:Pitfall drift-fence arrays and snake traps. Statistical analyses: Several measures of species richness and diversity analyzed relative to landscape position.

Species richness and diversity were generally highest in the Chino Hills (22 species) and Whittier Hills (14 species), with lower levels in the narrower, more fragmented areas between (10-12 species). The number of sensitive species declined from seven in the Chino Hills to four in the Whittier Hills, and the western limit for some species lies somewhere between Chino Hills and Whittier Hills. Several species (e.g., coast horned lizard, western skink, red diamond rattlesnake) showed decreased population densities moving west through the corridor.

Maintain habitat linkages to maintain gene flow and reestablishment of populations if localized extinctions occur.

PCR 2002 General
wildlife, with focus on large mammals.

Assess onsite biological resources and wildlife movement corridors to understand constraints to development on the ShellAera property.

Shell-Aera property and immediate vicinity; representing the western half of the Missing Middle (between SR-57 and Harbor Blvd.).

Sign reconnaissance; unbaited track stations, camera stations, and scat surveys focused on expected corridors and bottlenecks, such as road crossings; analysis of roadkill records.

Documented use of Shell-Aera property by deer, bobcat, coyote, roadrunners, and other native wildlife. Greatest evidence of wildlife movement was concentrated from the southeast corner of the property (associated with Tonner Bridge) to the northwest corner (associated with Drainage 26 and an area of high roadkill on Harbor Blvd.). Documented primary and secondary movement corridors across the property.

N/A--This biological constraints analysis describes existing conditions on the property and does not present recommendations.

Puente-Chino “Missing Middle” Analysis
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Methods
This study synthesized and updated existing information on wildlife distribution and movements in the Puente-Chino Hills Wildlife Corridor (see Table 1) to serve as a “meta-analysis” of overall corridor function and of the role that each portion of the corridor plays in supporting native wildlife and wildlife movement. After analyzing existing conditions, I also considered how land-use changes in the Missing Middle could affect the continued persistence of wildlife populations throughout the corridor and in each portion of the corridor. The analytical process involved

1. Selecting a suite of target species for which there is sufficient local information to assess distribution and movements;

2. Defining geographic units of the corridor system and assessing their functions in supporting these target species;

3. Assessing the roads that segment the study area as potential barriers or filters to movement; and

4. Assessing how the current functionality of these segments could change with various development scenarios.

Reconnaissance
The analysis of existing literature was supplemented with reconnaissance surveys in the field as well as using satellite imagery, high-resolution aerial photographs, and digital photographs taken during flyovers by Melanie Schlotterbeck. In particular I used the Keyhole program (www.keyhole.com) to perform a “virtual reconnaissance” of the study area, including properties where physical access was not possible. Keyhole3
allows a user to zoom, pan, tilt, rotate, and
otherwise explore a three-dimensional digital model of the Earth’s surface covered with high resolution satellite imagery (2004-5 color images at 1-m resolution) and Geographic Information System (GIS) data that can be layered onto this imagery. This proved to be an ideal tool for “exploring” the terrain prior to the field visit, and while reviewing previous studies in the area, to determine how topography, vegetation, development, and other landscape features might influence target species movements. By zooming in, rotating, tilting, and moving along this virtual landscape, a wildlife biologist can readily see where steep terrain, road cuts, bridges, vegetation, housing developments, and other landscape features would tend to funnel movements by larger species across the study area. (For example, I predicted, based on Keyhole reconnaissance, that the stretch of Harbor Boulevard just south of Wellington Lane would be a deadly road crossing for large mammals, which was later confirmed by personal observations in the field and my literature review.)

3 Reduced-resolution screen captures of Keyhole imagery are used to illustrate landscape issues throughout this report.

Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute 11 July 2005
After extensive exploration of the study area using Keyhole, GIS, and high-resolution aerial imagery, I visited the study area on March 2, 2005. I drove all roads crossing the area, stopping to investigate road-crossing structures (bridges, culverts, etc.), walking sections of trails, and looking for wildlife and wildlife sign. I photographed key locations, roadkills, habitat conditions, and other pertinent scenes, and noted signs of wildlife on aerial photographs.

Because my fairly cursory field observations strongly reinforced the quantitative results of more intensive studies (see Table 1), they are not presented in detail, but are cited as supporting or supplemental evidence for the results and recommendations of these previous studies.

Target Species
It is important to clearly define what species and ecological processes are expected to benefit from a wildlife movement corridor (Rosenberg et al. 1997, Beier et al. in press). Target species were selected based on data availability (see Table 1) and how well they reflect overall corridor function or serve as indicators of habitat fragmentation and movement constraints. They include species that require large areas to survive, are most susceptible to extirpation by habitat fragmentation, are most susceptible to roadkill, or for which roads may serve as physical barriers. In addition, previous studies provide some more general measures of ecosystem health and corridor function, such as species richness for amphibians and reptiles (Haas et al. 2002) and avifauna (Cooper 2000).

Although it is tempting to think of one or a few larger mammal species as most obviously served by movement corridors, the ecological effects are far broader than any single species or set of species. Ultimately, the objective of securing and managing the Puente-Chino Hills Wildlife Corridor is more than ensuring that mountain lions can continue roaming the area (although that is certainly one objective)—it is ensuring that healthy ecological communities can continue to thrive and support the broadest possible range of native species.

Mountain Lion
The mountain lion or puma (Puma concolor) is the top carnivore in Southern California. It is a true “keystone” species whose presence helps maintain ecological balance by controlling populations of deer and other prey (Soulé and Terborgh 1999, Crooks and Soulé 1999).

Mountain lions require huge contiguous habitat blocks to persist, with individual lions roaming home ranges as large or larger than the entire Puente-Chino Hills study area. Only contiguous habitat areas large enough to support at least 20 individuals—about 2,000 sq. km in Southern California—are expected to support lion populations over even the short term (Beier 1993, Beier et al. in press). Due to demographic instability and inbreeding concerns, even populations meeting these criteria, such as the population of about 20 adult lions occupying the 2,070-sq.-km Santa Ana Mountains Range, must be connected to even larger populations for long-term persistence (Beier 1993).

Although the Puente-Chino Hills are too small (at about 163 sq. km) to support a population of mountain lions on their own, one to several lions live totally or partially within the hills as an Puente-Chino “Missing Middle” Analysis
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extension of the larger Santa Ana Mountains population (Beier 1993, Noss et al. 1997). The Coal Canyon wildlife underpass on Highway 91 was restored specifically to ensure the continued presence of these large predators in the Puente and Chino Hills, thus ensuring a more healthy and balanced ecosystem (Noss et al. 1997). Lions have been detected all the way to the westernmost portions of the corridor (Whittier Hills) in recent years (A. Henderson, A. Gullo, and C.

Schlotterbeck, personal communications).

Lions are very prone to roadkill. During Beier’s (1993, 1995) study of mountain lions in the Santa Ana Mountains, vehicles killed 33% of the population, including four lions killed at one road-crossing during a 2-year period. Thus, mountain lions are good focal species for conservation planning in the study area, due to their keystone status, large area requirements, dependence on intact corridors, and susceptibility to roadkill.

Bobcat
Bobcats (Lynx rufus) are excellent indicators of functional landscape connections at the scale of interest in the Puente-Chino Hills study area (Crooks 2002, Haas 2002, Tigas et al. 2002, Riley et al. 2003). In Southern California, bobcat home ranges average about 2 to 6 sq. km, and population densities average about 1.1 to 1.6 bobcats per sq. km (Riley et al. 2003, Lembeck 1978, Lyren 2001). The probability of bobcat occurrence in a habitat patch is directly related to both the size of the patch and its isolation from other patches (Crooks 2002), with patches as small as 10 sq. km highly likely to support a few individuals if they are close enough together (within 1 km or less) and adequately connected to allow inter-patch movement (Crooks 2002).

Using radio telemetry in the Santa Monica Mountains, Riley et al. (2003) found habitat blocks as small as 3.15 sq. km to support a few individuals, as long as movement was possible to larger, source population areas. Taking into account variation in habitat quality, Beier et al. (in press) concluded that contiguous habitat blocks of about 60 sq. km are necessary to support potential source populations of 20-25 adult bobcats over the short term in Southern California. Noss et al. (1997) estimated that a population of less than 50 bobcats inhabited the Puente and Chino Hills and less than 500 bobcats inhabited the Santa Ana Mountains. Haas (2002) found bobcats to be associated with wider portions of the Puente-Chino Hills, with lower densities in narrower segments. He concluded that bobcats used smaller segments primarily as “move-through” rather than “live-in” habitat.

Bobcats are behaviorally secretive and tend to avoid roads and other human disturbances, although they remain quite susceptible to roadkill. Bobcats are less likely to use road underpasses than coyotes, especially narrow underpasses or underpasses near residential areas, and so may be better indicators of high-quality road-crossing structures for wildlife.

Coyote
Coyotes (Canis latrans) are more adaptable, more abundant, and less averse to fragmentation than bobcats and mountain lions—and thus less dependent on high-quality landscape connections. Nevertheless, coyotes are important to maintaining ecological balance (Crooks and Puente-Chino “Missing Middle” Analysis
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Soulé 1999) and are good indicators of problem road-crossings, as many are killed on roads in the study area and elsewhere (Lyren 2001, Haas 2000, Robertson et al. 1995). Concentrations of coyote roadkills provide good indicators of potential crossing locations for other species, including bobcats, mountain lions, and mule deer. Noss et al. (1997) estimated a carrying capacity of roughly 60 adult coyotes for the Puente and Chino Hills and less than 500 in the Santa Ana Mountains.

Mule Deer
Mule deer (Odocoileus hemionus) are the primary prey of mountain lions and require relatively large habitat areas to support populations. Although they adapt to living in close proximity to humans, and are found in portions of the study area that are effected by fragmentation and development edges (Haas 2000), they are prone to roadkill and highly selective of road-crossing structures. In general, deer will use only the largest, most open types of structures (bridges or very open box culverts) within well-vegetated habitat areas to cross under (or over) roads (Haas 2000, Clevenger and Waltho 1999, Evink 2002). Noss et al. (1997) estimated that about 400 mule deer may inhabit the Puente and Chino Hills and about 4,000 may inhabit the Santa Ana Mountains.

Greater Roadrunner
Greater roadrunners (Geococcyx californianus) are associated with coastal scrub and open brush mosaics in coastal Southern California. They are highly susceptible to roadkill (Unitt 2004) and particularly sensitive to habitat fragmentation, rapidly disappearing from isolated habitat patches (Unitt 2004, Crooks et al. 2001, Soulé et al. 1988, Garrett and Dunn 1981). Soulé et al. (1988) and Crooks et al. (2001) identified the roadrunner as the most sensitive to habitat fragmentation of eight scrub-dwelling species they addressed in San Diego County. Crooks et al. (2001) found roadrunners persisting in only one of 34 canyons isolated by urbanization, and estimated that the roadrunner has a good chance of persisting only in patches 1.6 sq. km or larger. Based on more exhaustive surveys, Unitt (2004) concluded that this underestimates roadrunner sensitivity to isolation; he suggested that even 4.0-sq. km patches may be too small to sustain populations for long. As snakes and lizards are important prey, roadrunners may decline with reductions in reptile diversity and abundance.

Cooper (2000) reported that roadrunners are scattered in association with scrub habitats throughout the Puente-Chino Hills study area, with particular concentrations in the hills north of Brea and Yorba Linda (including significant portions of the Missing Middle). He estimated there were more than 50 breeding pairs (100 adult individuals) living in the Puente and Chino Hills.

Coast Horned Lizard
The coast horned lizard (Phrynosoma coronatum) was once common and widely distributed in coastal sage and chaparral habitats of Southern California, but has been extirpated from much of Puente-Chino “Missing Middle” Analysis
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its former range by habitat loss and fragmentation (Fisher et al. 2002). This species is highly impacted by edge effects, such as invasions by the nonnative Argentine ant, which eliminates the native harvester ants that comprise more than 95% of the horned lizard’s diet (Suarez et al. 2000). Argentine ants are closely associated with human-altered (especially irrigated) landscapes in Southern California, but can invade hundreds of meters into native scrub habitats; their adverse effects on native invertebrate populations ripple through the ecological community with devastating effects on biological diversity (Suarez et al. 1998). Thus, horned lizards serve as good indicators of relatively intact ecological webs and processes or, conversely, of the adverse effects of habitat fragmentation and edge effects on ecological communities (Fisher et al. 2002). They are also highly susceptible to roadkill and trampling. Case and Fisher (1998) and Haas et al. (2002) found coast horned lizards in the Chino Hills, as far west as the ridges between Carbon Canyon and Tonner Canyon (near the Olinda Landfill), but did not detect them at points farther west. Therefore, this species may already be extirpated, or likely will be soon, in corridor segments west of Highway 57 due to isolation of populations by roads and high mortality in remaining habitat areas.

Other Target Resources
The above target species certainly do not comprise a complete list of resources subject to loss due to habitat fragmentation and associated effects. They serve as indicators for a much more diverse community of organisms, and were chosen largely on this basis as well as the availability of distribution data in the study area. In addition to these species, I examined information on the diversity and abundance of reptiles and amphibians (from Case and Fisher 1998, Haas et al. 2002) and birds (Cooper 2000), and considered, at least qualitatively, the effects of habitat fragmentation on other species and ecological processes in the study area.

Defining Geographic Units, Barriers, and Filters
Although the entire study area serves as a wildlife movement corridor at a gross scale, it functions more like a peninsula of somewhat discrete habitat blocks segmented by roads and other discontinuities (Haas 2000, Haas and Crooks 1999, Schlotterbeck 2001, Robertson et al. 1995). The Puente-Chino Hills Wildlife Corridor was therefore subdivided into discrete geographic units based on habitat contiguity and intervening roads. Each unit, including the Santa Ana Mountains (the core area from which the corridor system projects) and the isolated terminal segment at the Whittier Narrows (Robertson et al. 1995), was given a geographic name to facilitate comparison (Map 2). Following Haas and Crooks (1999), the seven units between these two extremes (or between Highway 91 and Interstate 605) were also numbered 1 to 7, from east to west. These seven segments comprise the functional Puente-Chino Hills Wildlife Corridor system. They are convenient for comparing results across the various field studies and for assessing how each segment, and the habitat breaks between them, contribute to overall functionality of the corridor system. These segments are therefore useful tools for conservation planning.

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Map 2. Geographic units of the Puente-Chino Hills Wildlife Corridor.

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Initial Classification of Geographic Units
Each geographic unit was first classified by the primary role it appears to play in the overall functioning of the wildlife corridor system—as a biological core, subcore, patch, or isolate.

These functional categories, defined below, reflect the relative size and contiguity of the units and their ability to sustain populations or facilitate movements of target species, as supported by literature and results of previous wildlife studies here. These definitions are tailored to this particular study, based on well established conventions in reserve design (e.g., Noss 1987, Meffe and Carroll 1997, Soulé and Terborgh 1999), and modified slightly from concepts and definitions developed for the South Coast Missing Linkages project—a science-driven approach to conserving landscape connectivity throughout the South Coast ecosystem (Beier et al. in press). The most significant deviation from the definitions of Beier et al. (in press) is the inclusion of an intermediate-sized “subcore” class (which corresponds to a “patch” in Beier et al. in press).4

• Core — A core area must be large enough (> 2,000 sq. km) to sustain populations of most or all target species without the need for frequent immigration from other areas, and should have relatively high biological diversity and a low proportion of edge. Core areas support source populations of target species, which may contribute individuals to other, less substantial, blocks of habitat. Basically, a core should be large enough to support a population (at least over the short term) of the most wide-ranging and area-dependent target species, which in this case is the mountain lion. • Subcore — Subcores are contiguous blocks of habitat at least 60 sq. km, but less than 2,000 sq. km (corresponding to a “patch” as defined by Beier et al. in press). Subcores are too small to sustain a population of mountain lions in isolation, but large enough to support a population of bobcats with at least occasional dispersal. Subcores may support one or a few individual mountain lions, or at least provide significant “live-in” habitat as part of one or more lion home ranges. Subcores are more edge-effected than cores and may sustain lower overall species diversity, but can nevertheless represent significant source populations for numerous other target species, such as roadrunners, coyotes, and horned lizards.
• Patch — Patches, at less than 60 sq. km, are smaller and more edge-effected than subcores and are expected to support overall lower numbers and diversity of species. In isolation, patches may be too small to support a population of bobcats, and perhaps other target species having intermediate area requirements, although they could support a small number of such species or at least represent live-in or move-through habitat for individuals of such species. Although they may support populations of less area-

4 Concepts like “core” and “corridor” are species- and scale-dependent, such that what might be considered a movement corridor for one species (e.g., mountain lion) can be core “live-in” habitat for other species (e.g., lizards, songbirds, or rodents). This entire study area is widely recognized as a “wildlife corridor,” even though numerous on-the-ground travel routes, population concentrations, etc., can exist within this overall corridor system at finer resolution.

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dependent target species, patches may serve mainly as dispersal stepping stones (or “move-through” habitat) for individuals of larger species (like mountain lions) moving between larger geographic units.
• Isolate — An isolate is any patch that is separated from another geographic unit by barriers to movement for target species. For example, the Whittier Narrows are separated from the Whittier Hills by Interstate 605, other significant roads, and commercial development, and are considered functionally isolated from the corridor for nearly all reptiles, amphibians, and mammals (Haas and Crooks 1999, Haas et al. 2000, Robertson et al. 1995, personal observations).

Note that these initial landscape categories were defined based primarily on the needs of the most area-dependent target species (mountain lion and bobcat). However, such concepts as “core” and “patch” can also be defined separately for each target species, based on their own requirements. Thus, a patch of habitat too small to support mountain lions could represent a “core” population area for less area-dependent species, like the roadrunner or horned lizard.

Such species-specific issues were treated in more detail in later analytical steps.

Classifying Barriers and Filters to Movement
Roads and other discontinuities in habitat were also classified based on their relative effects on movements and population distributions of species, as follows:
• Barriers and Near Barriers — Roads or other discontinuities between geographic units that are never (for barriers) or rarely (for near barriers) crossed by target species. Barriers effectively isolate target species populations on adjacent habitat units from one another, while near barriers may separate subpopulations into a “metapopulation” system, with individuals occasionally dispersing between subpopulations in different units. For wideranging species like bobcats or mountain lions, barriers or near barriers may define one boundary of a home range, as individuals recognize it as the edge of available habitat.

Major freeways and associated physical features (e.g., embankments, drainage improvements, retaining walls, lane dividers, fences, wide areas devoid of vegetation) create impassible barriers for nearly all ground-dwelling species, unless sufficient crossing structures (e.g., bridges, culverts, vegetated over-crossings) facilitate movements (Beier et al. in press, Evink 2002, Haas 2002, Lyren 2001). For example, the concentration of roads and commercial developments associated with Interstate 605, separating Whittier Hills from Whittier Narrows, represents a barrier for most or all target species. Near barriers are similar, but they may have one or more crossing structures that can be used by at least some target species; or target species may occasionally cross atgrade, on the road surface (perhaps at high risk of roadkill). Highway 57 and Harbor Boulevard are examples of near barriers in the study area. Both have high traffic volumes and physical characteristics that discourage crossings, except at one excellent bridge crossing at Tonner Canyon (for Highway 57) and one stretch where wildlife cross Harbor Boulevard at-grade—albeit with frequent roadkill.

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• Filter (Permeable and Highly Permeable) — Filters are discontinuities in habitat connectivity that are readily to moderately crossable by most but not all target species.

For example, two-lane paved roads with low traffic volumes and little associated development are readily crossed by larger mammals (although there may be occasional roadkill); but other species, like horned lizards, may be reluctant to cross or may suffer high roadkill. Thus, such roads serve to “filter” some species out of the community of wildlife crossing between adjoining habitat units. Several permeable to highly permeable roads cross the study area, such as Turnbull Canyon Road through the Whittier Hills (between Segments 6 and 7). The larger mammals, roadrunners, and some reptiles probably cross this road at-grade with little hesitation, and individual home ranges may straddle it. However, some smaller or more sedentary species may have their populations segmented by this road into subpopulations, with only occasional cross-road dispersal.

Analyses — Assessing Existing and Future Functionality
For each target species, I followed the following analytical steps:

1. I assigned each of the nine geographic segments to one of the functional categories (core, subcore, patch) as if each functioned independently of the others (i.e., as if roads separating the units acted as barriers or near barriers to dispersal). This initial categorization was based exclusively on unit size. For example, any unit less than 60 sq. km would be considered a patch if it functioned independently of other units in supporting a target species.

2. I assessed each road separating the units to determine whether it acted as a barrier (or near barrier) or filter (permeable to highly permeable). If a road was not considered a barrier/near barrier for a target species, and the two units it separated appeared to function as one larger unit for that species, the area of the two units was summed and the function of the new composite unit was reassessed. For example, if the composite unit exceeded 60 sq. km, it was considered to function as a subcore rather than two separate patches.

3. Based on this revised, species-specific functionality assessment, I assigned each newly defined unit (or composite unit) a function relative to supporting individuals or populations of each target species based on unit size, habitat composition, and other factors gleaned from the literature and field reconnaissance. These species-specific functions were defined as follows:
• Population — capable of supporting a breeding population of at least 20 adults and potentially serving as a source of individuals that disperse into other units. • Subpopulation — capable of supporting at least two but less than 20 breeding individuals. Not likely to be a reliable source population, but may exchange individuals with other areas within a larger metapopulation (a set of partially isolated Puente-Chino “Missing Middle” Analysis
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populations linked by occasional dispersal) and may provide individuals to recolonize habitat patches in case of local extirpation.
• Home Range Part — incapable of supporting at least two breeding individuals on its own, but may provide live-in habitat (e.g., foraging or resting cover) and form a part of one or more individuals’ home range(s).
• Move-through — not contributing significant live-in habitat for a species as part of a functional home range, but capable of accommodating movements between more substantial units within a home range, or potentially used for dispersal between other habitat units.

4. This classification system was used to assess likely effects of future scenarios on wildlife populations or movements, such as (a) adding new roads or development that would introduce new barriers or reduce the size of a functional unit, or (b) adding or improving wildlife crossing structures that would allow two independent units to serve as one larger one.

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Results
Functionality of Geographic Units
Table 2 summarizes characteristics of the geographic units, including their size, vegetation composition, known or inferred presence/absence of target species, initial functional classification (core, subcore, patch), and reserve status (conserved/unconserved). Only the Santa Ana Mountains unit met the definition of a core area (larger than 2,000 sq. km and capable of supporting a mountain lion population). The Chino Hills between Highways 91 and 142 met the definition of a subcore (60-2,000 sq. km and capable of supporting a population of bobcats). Six other segments of the Puente-Chino Hills Wildlife Corridor met the definition of patch, but with great variation in their capacity to support wildlife and wildlife movements. The disjunct Whittier Narrows met the definition of an isolate.

Table 3 summarizes pertinent characteristics of the major roads dividing these units, with a focus on their role as barriers or filters to wildlife movement. Following below is a more detailed, unit-by-unit review of the information, concerning how each unit appears to function in supporting wildlife populations and movements, considering the effects of intervening roads and other factors. This review starts with the Santa Ana Mountains Core Area, then describes the seven segments of the functional Puente-Chino Hills Wildlife Corridor, and ends with the isolated Whittier Narrows.

Santa Ana Mountains (Core)
At about 2,070 sq. km, wildlands in the Santa Ana Mountains comprise the only true core in the study area. They support a high diversity of wildlife in a relatively intact and healthy representation of Southern California’s South Coast ecosystem (Spencer et al. 2001), including substantial populations of all the target species. Noss et al. (1997) estimated populations of breeding adults in the Santa Ana Mountains at about 4,000 mule deer, 15-20 mountain lions, up to 500 bobcats, and more than 500 coyotes. These populations are large enough to persist, at least in the short term, within the Santa Anas without immigration from other habitat areas— although at least the mountain lion needs occasional immigration from adjacent mountain ranges to persist in the long term (Noss et al. 1997, Beier 1993). Of course, all species and ecosystem functions benefit from connectivity to other wildlands. The breeding population of about 15-20 mountain lions serves as a source of lions moving into the Puente-Chino Hills via the Coal Canyon Underpass (Beier 1995, Noss et al. 1997).

The Santa Ana core area is separated from the Chino Hills by busy Highway 91 and associated developments. However, the Coal Canyon Wildlife Underpass was restored specifically to mitigate this strong barrier to movements and appears to be functional (Figure 2).

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Segments of the Functional Puente-Chino Hills Wildlife Corridor Santa Ana
Mountains Chino
CarbonTonner Shell-Aera Powder- Schabarum San Miguel E. Whittier W. Whittier Whittier Narrows Segment Number N/A 1 2 3 4 5 6 7 N/A Size (sq. km.) ~2,070 85.6 44.3 13.3 5.7 1.5 5.2 7.1 ~4.5 Vegetation Mosaic Shrubland 51.3% 51.9% 45.2% 48.9% 57.1% 43.4% 67.0% Grassland 36.5% 29.4% 37.7% 21.0% 31.8% 36.1% 17.1% Woodland 12.1% 18.7% 17.2% 30.1% 11.4% 20.4% 15.9% Wetland N/A

0.1% 0.1% 0.0% 0.0% 0.0% 0.0% 0.0%
N/A
Spp. Presence/Absence* Mountain lion P P P P? P? P? P P A? Bobcat P P P P P P P P A? Coyote P P P P P P P P P? Mule deer P P P P P P P P ? Roadrunner P P P P P? P? P P ? Coast horned lizard P P P A? A? A? A? A? A? Biological Function core subcore large patch patch patch small patch patch patch isolate Reserve Status substantially conserved
substantially
conserved
Carbon Cyn
partly
conserved,
Tonner Cyn
unprotected &
threatened
unprotected
& threatened
partly
conserved,
partly
threatened
partly
conserved,
partly
threatened
substantially
conserved
substantially
conserved
substantially
conserved
*See Table 1 for supporting literature. P = confirmed present; A = likely absent; ? = presence or absence inferred by indirect evidence and geographic context, but no confirmatory data found.

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Major, 6-lane freeway with heavy traffic and significant physical barriers to wildlife.

Barrier, except for Coal Canyon Underpass
Carbon Canyon Rd. (SR 142)
Chino/Carbon-Tonner Square box culvert near
Chino State Park entrance.

Busy 2-lane highway through mostly wild open space. Moderate-high coyote roadkill. Few physical barriers.

Permeable filter, with some roadkill (esp. coyote). Mix of at-grade crossings and culverts, at least one used by bobcat.

SR 57 Carbon-Tonner/ShellAera Tonner Canyon Bridge Major 6-lane freeway with heavy traffic and significant physical barriers to wildlife. Barrier except for Tonner Canyon Bridge, with documented use by deer, bobcat, and coyote.

Harbor Blvd. Shell-Aera/PowderSchabarum Harbor Blvd. Wildlife Tunnel (proposed) Major 4-lane arterial with heavy traffic and significant barriers to wildlife. High roadkill. Barrier, except for occasional at-grade crossing, with very high roadkill. Hacienda Blvd. Powder-Schabarum/San Miguel
none (except a littleused equestrian tunnel that could be improved) Busy 2-lane road with steep slopes and cut banks, but several at-grade crossing areas.

Filter, with moderate roadkill risk.

Colima Rd. San Miguel/East Whittier Colima Service Tunnel Busy 4-lane road with physical barriers, including fences that may help funnel wildlife to undercrossing.

Filter, with relatively low roadkill due to fences and a well-used undercrossing with known use by deer, bobcat, and coyote.

Turnbull Canyon Rd.

East Whittier/West Whittier
none Winding, 2-lane road with light traffic
through wild habitat.

Highly permeable filter, with at-grade crossings in wild open space.

Interstate 15 & Workman Rd.

West Whittier/Whittier Narrows
none Major 6-lane freeway with heavy traffic, plus
other major and minor roads, commercial development, and other physical barriers to wildlife.

Barrier to essentially all ground-dwelling species.
*Includes only those structures used by diverse target species and especially larger mammals. Numerous smaller culverts that may serve some target species also occur, as do some larger equestrian tunnels that are in landscape positions not favoring use by target species. See Haas (2000) and Robertson et al. (1995) for a more comprehensive review of crossing structures in the study area.

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Figure 2. View northwest across Coal Canyon Wildlife Underpass, which links wildlife movement between the Santa Ana Mountains and Chino Hills State Park (Keyhole screenshot).

Corridor Segment 1—Chino
At over 85 sq. km, the Chino Hills represent a substantial subcore supporting diverse and relatively healthy ecological communities. It supports one to a few mountain lions, forming at least a portion of their home ranges, due to its connection to the Santa Ana Mountains population via the Coal Canyon Wildlife Underpass. Segment 1 also supports significant populations of all other target species (Lyren 2001, Cooper 2000, Haas and Crooks 1999, Haas 2000, Noss et al. 1997) and has higher overall biological diversity than other segments. For example, of all the segments they sampled for reptiles and amphibians in the Puente-Chino Hills Wildlife Corridor, Haas et al. (2002) reported the highest richness of herpetofauna (22 species captured) in the Chino Hills. They further reported the highest levels of species diversity (using a variety of diversity indices) and evenness (an index of relative abundance across all species) in the Chino Hills, with a general decline in these measures as one moves west through the corridor.

Moreover, the number of sensitive amphibian and reptile species recorded by the study dropped from 7 in the Chino Hills to 4 in the Whittier Hills. No western spadefoot toads (Spea hammondii), western pond turtles (Clemmys marmorata), coast horned lizards, or coast patchnosed snakes (Salvadora hexalepis) were found west of the Chino Hills. These results Puente-Chino “Missing Middle” Analysis
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undoubtedly reflect the larger size of Segment 1 (and adjoining Segment 2) compared with other segments, its proximity to the Santa Ana Mountains Core, and the increasing number of barriers and filters encountered moving west from this source area through the corridor. Similar patterns in diversity, abundance, and evenness measures would be expected for other taxa (e.g., birds, small mammals, insects, plants) if comparable data were available to document them.

Segment 1 is largely conserved already as Chino Hills State Park, although efforts continue to increase the size and buffering of this important reserve area. It is separated from Segment 2 by Carbon Canyon Road (Highway 142). This busy 2-lane road suffers some roadkill, especially coyote (Robertson et al. 1995), but is generally quite permeable to target species due to extensive, naturally vegetated land on both sides, lack of development over much of its length, and availability of several undercrossings. The most significant undercrossing is a 1.4-m (4.5-ft) high square box culvert used by bobcats and other target species (Robertson et al. 1995). This road is therefore classed as a permeable filter, allowing Segments 1 and 2 to function as one larger subcore for most species and ecological processes. Notably, Haas et al. (2002) and Case and Fisher (1998) recorded coast horned lizards on both sides of Carbon Canyon Road, but not farther west along the corridor.5
Corridor Segment 2—Carbon-Tonner
This large (44.3 sq. km) patch appears to function more as an extension of the Chino Hills subcore, being separated only by permeable Carbon Canyon Road (see previous). It is biologically diverse and supports all target species, including the westernmost observations of horned lizards by Haas et al. (2002) and Case and Fisher (1998). The southern portion of Segment 2 (including lower Carbon and Tonner Canyons and associated ridges) has been identified as a conservation priority for birds due to its support of several regionally rare or declining species, including greater roadrunners, loggerhead shrike, cactus wren, California gnatcatcher, grasshopper sparrow, and sage sparrow, among others (Cooper 2000). The northern portion of the segment (upper Tonner Canyon) is also rated as a conservation priority for birds, including golden eagle, burrowing owl, northern harrier, cactus wren, tricolored blackbird, and grasshopper sparrow, among others (Cooper 2000). Tonner Canyon also supports significant California walnut woodlands.

The eastern half of Segment 2 contains the western slopes and ridges of the Carbon Canyon landscape and is partially conserved as part of Chino Hills State Park and the Firestone Scout Reservation. The western half of this segment, containing most of Tonner Canyon, is unconserved and threatened by several proposed developments. Tonner Canyon is almost entirely owned by the City of Industry, which proposes a new road along the east side of Tonner Canyon (Map 2) and new water reservoirs within the canyon. This threatened half of the segment comprises the eastern portion of the Missing Middle.

5 During my literature review, I found no recent confirmed records for coast horned lizards farther west than a ridge between Carbon and Tonner Canyons near Olinda Landfill (Haas et al. 2002). However, one table in a draft report (LSA 2005) listed the species as “observed” in the Whittier Hills, although another table in the same reference indicated the horned lizard as potentially present but not observed there.

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Figure 3. View northeast across Tonner Bridge and Highway 57 (Keyhole screenshot).

Wildlife on both sides of Highway 57 (a barrier road) are funneled to cross under Tonner Bridge.

The Olinda Landfill occupies a large footprint in the south-central part of Segment 2, between Tonner and Carbon Canyons. The landfill eventually will be closed and restored to natural vegetation as a County regional park, adding to the area of conserved open space here (C.

Schlotterbeck, personal communication).

Segment 2 is divided from Segment 3 by busy Highway 57. This freeway is a near total barrier to ground-dwelling wildlife, except for one high-quality underpass in lower Tonner Canyon (Figure 3 and Photo 1). This bridge over Tonner Creek is very wide and open, with sufficient natural cover to facilitate movement by all target species. The bridge is used by mule deer, bobcat, coyote, and numerous other species (PCR 2002, Haas 2000, Haas and Crooks 1999, Robertson et al. 1999, personal observations). Maintaining this function is widely considered critical to maintaining the functional Puente-Chino Hills Wildlife Corridor, but it is threatened by the City of Industry plan for a new road originating here and traveling up Tonner Canyon to Diamond Bar.

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Corridor Segment 3—Shell-Aera
This segment, between Highway 57 and Harbor Boulevard, comprises the western portion of the Missing Middle. It is named for the Shell-Aera Master Planned Community property (2,935 acres or 11.9 sq. km), which comprises 90% of the segment’s remaining undeveloped land and is proposed for development. In addition to the Shell-Aera property, Segment 3 includes some privately owned open space lands conserved as mitigation for previous developments in the vicinity, such as the Shea homes development off of Harbor Boulevard in the northwest portion of the segment.

Although smaller than Segments 1 and 2, and bounded by two near-barrier roads, this substantial habitat block (13.3 sq. km) supports diverse vegetation and wildlife communities and is generally recognized as essential to maintaining connectivity through the Puente-Chino Hills Wildlife Corridor (PCR 2002, PCR 2000, Haas 2000, Robertson et al. 1995, personal observations). Cooper (2000) recognized the area as being of high conservation concern for its support of rare or declining bird species, including greater roadrunner, golden eagle, and grasshopper sparrow, among others. The Shell-Aera property was not open to sampling by most studies included in this analysis. However, PCR (2002) performed biological surveys on the property and confirmed presence and movements of all target species except mountain lion and horned lizard. Although horned lizards are likely extirpated here, mountain lions undoubtedly do use the property—probably both as move-through habitat and as foraging habitat. There is essentially no other way for lions to make it to segments farther west, where lion presence has Photo 1. View east under the Tonner Bridge, the only functional crossing beneath Highway 57 for deer, mountain lion, bobcat, and other wildlife species.

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Figure 4. View northwest across Segment 3 and Harbor Boulevard to Segment 4, indicating general trends in wildlife movements (Keyhole screenshot). Arrow widths indicate inferred relative use levels.

Red dots indicate stretch of highest roadkill.
been confirmed (A. Henderson, A. Gullo, and C. Schlotterbeck, personal communications), from the source populations to the east. The segment also supports deer and other prey species and appears to have suitable cover, despite a history of grazing that has degraded woodland and shrubland habitats. The Shell-Aera property also supports some of the best remaining examples of California walnut woodland in Southern California (approximately 16,000 walnut trees covering 475 acres), although regeneration has been hampered by grazing (Quinn 1998, in PCR 2002).

Harbor Boulevard, which forms the western boundary of Segment 3, is a formidable barrier to target species movement. It is wide, with fast and heavy traffic, and currently lacks any underpasses. A combination of natural and man-altered topography tends to funnel wildlife to a stretch of road just south of the Shea Homes development, where a steep-sided riparian drainage (“Drainage 26”) abuts a steep fill slope below the road, adjacent to housing (Figure 4). A variety of wildlife trails converge here, and several cross the road and continue northwest along a powerline right-of-way into Powder Canyon. Signs of target species usage (bobcat, deer, coyote) are especially abundant in Drainage 26, and roadkill frequency is very high in this stretch of road, especially for coyote (PCR 2002, Robertson et al. 1995, personal observations). Figure 4 illustrates major movement concentrations on the Shell-Aera property as they relate to this problem road-crossing area. Photo 2 shows a road-killed coyote I observed on March 2, 2005, Puente-Chino “Missing Middle” Analysis
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where Harbor Boulevard crosses the Shea Homes development after Drainage 26. I surmised that this coyote entered the roadway out of Drainage 26 via one of several clear wildlife trails.

Fortunately, recognition of this problem road-crossing has resulted in approval of a wildlife underpass here, although fencing to direct wildlife to the tunnel, considered essential to its success, has not been approved on the Shell-Aera property (A. Henderson, personal communication).

Corridor Segment 4—Powder-Schabarum
This segment (about 5.7 sq. km) is relatively small but nevertheless significant, especially as a link between larger habitat units to the east and west. Deer, bobcat, and coyote are commonly seen moving through the segment (Robertson et al. 1995). Haas (2000) recorded a lower frequency of bobcat visitations to track stations in this segment (and adjoining Segment 5) than in larger segments in the study area, which he attributed to the narrowness of this stretch of the wildlife corridor and consequently greater edge effects and disturbance factors.

Powder Canyon open space makes up the southern portion of Segment 4, and Schabarum Regional Park makes up the northern portion. The segment averages about 1.5 km wide over most of its length, but narrows to about 0.5 km in the western portion approaching Hacienda Boulevard. Wildlife movement becomes quite constrained in this narrow portion by existing housing, fences, and other impediments. Hacienda Boulevard separates this constrained portion of Segment 4 from Segment 5. Although Hacienda Boulevard has lower traffic volumes and speeds than the highways discussed above, it has very steep slopes and cuts, with no reliably Photo 2. View southeast across the Harbor Boulevard “deathtrap.” Drainage 26 extends out of view to the left from the bend in Harbor Boulevard. Note road-killed coyote and heavy traffic.

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used crossing structures. An existing equestrian tunnel, that is infrequently used by target species, could be improved with fencing and revegetation (Haas 2000 and personal observations). Hacienda Boulevard has several at-grade crossing concentrations and trails (Haas 2000, Robertson et al. 1995, personal observations), which are probably associated with moderate roadkill. I rated this as a permeable filter, as it is crossable by most target species; however, it may act as a strong filter due to these and other constraints, and it represents a bottleneck to movement in need of improvement (Haas 2000).

Corridor Segment 5—San Miguel
This is the smallest (1.5 sq. km) segment of the entire corridor system. Along with the narrow constriction in the west end of Segment 4, this segment represents the narrowest habitat constriction along the wildlife corridor system (0.5 to 1.0 km wide). It is also perhaps the most disturbed by humans and their pets, particularly on northern slopes (Haas 2000, Robertson et al. 1995). Haas recorded low use by target species (no bobcat use) on the northern portions of this segment, along the Skyline Trail, but high levels of cats, dogs, striped skunks, and raccoons. The abundance of these mesopredators that are adapted to human environments often reflects low presence of coyotes and other large predators, which suppress these species when present (Crooks and Soulé 1999), as well as higher human influences and edge effects. Haas (2000) recorded bobcat activity in the southern portion of the segment, in association with less disturbed areas of San Miguel Canyon and near Skyline Drive. He noted that the transects with the greatest bobcat activity were also those with the lowest dog activity. Haas surmised (as did Robertson et al. 1995) that large mammals travel along Skyline Drive and descend into San Miguel Canyon towards the Colima Service Tunnel (discussed below). Low density housing in this segment, especially near Hacienda Boulevard, may reduce habitat quality for target species, but does not present barriers to movement (Haas 2000, Robertson et al. 1995). For some target species, Segment 5 may function primarily as move-through habitat, although a few coyotes and bobcats probably forage in San Miguel Canyon.

Segments 5 and 6 are divided by Colima Road, a fairly busy 4-lane road winding through a mix of open space and scattered housing. Although flanked by steep slopes, some fences, and other movement impediments, there are several at-grade crossing areas, which are associated with high coyote roadkill (Haas 2000, Robertson et al. 1995). One good under-crossing structure exists at a service tunnel near the southern edge of the habitat area (Colima Service Tunnel). Bobcats, coyotes, and deer use this tunnel (Robertson et al. 1995, Haas 2000, Haas and Turschak 2002), and they continued using it even after a dramatic increase in recreational uses of the tunnel and vicinity by humans and dogs during 2001-2002 (Haas and Turschak 2002). Most wildlife species use the tunnel between sunset and sunrise, whereas human and dog use occurs almost exclusively during daylight (Haas and Turschak 2002). Conserving and improving this tunnel for continued wildlife use, especially at night, is a conservation priority.

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Corridor Segments 6 and 7—East Whittier and West Whittier The wildlife corridor widens again in the Whittier Hills from the narrow and constrained Segments 4 and 5. Segments 6 and 7 are separated by Turnbull Canyon Road, which appears to be the most permeable road analyzed in the study area. It is a narrow, 2-lane road with relatively light traffic, winding through fairly undisturbed wildlands. Haas (2000) recorded no roadkills here and did not consider Turnbull Canyon Road a barrier or major hazard to mammals.

Likewise, Robertson et al. (1995) did not consider Turnbull Canyon Road a significant impediment to movement, which corresponds with my field observations. Consequently, Segments 6 and 7 are discussed here together as one continuous geographic unit (Whittier Hills).

The Whittier Hills support significant biological values despite their location at the terminus of the range of connected wildlands, far from the Santa Ana Mountains Core. This area had the highest levels of deer and bobcat activity recorded by Haas (2000), and higher species richness of reptiles and amphibians than narrower segments farther east (Haas et al. 2002). Mountain lion presence has recently been confirmed in the area by several lion-predated goats and deer, and at least one likely lion scat (Haas 2000; A. Henderson, C. Schlotterbeck, and A. Gullo, personal communications).

However, monitoring results also show that the Whittier Hills have lost some species and may be close to losing more due to their distance from core areas and numerous intervening barriers and filters to movement. For example, despite the relatively high total number of reptile and amphibian species they recorded here, Haas et al. (2002) also found the Whittier Hills to have the lowest overall evenness in the study area (Haas et al. 2002). This evenness finding means that the local herpetofauna consists of a few abundant species plus many less abundant species, in contrast to the Chino Hills, where high evenness indicated healthy populations of most species.

Those species detected in low numbers in the Whittier Hills may represent remnants of dwindling populations, possibly on their way to extirpation with little hope of being “rescued” by new colonists from other areas (Brown and Kodric-Brown 1977) due to the great distances and numerous barriers involved. Moreover, the Whittier Hills support fewer sensitive species of reptiles and amphibians than the Chino Hills, as various species drop out in an apparent east-west gradient from the Chino Hills through the wildlife corridor to the Whittier Hills (Case and Fisher 1998, Haas et al. 2002).

The Whittier Hills are separated from the Whittier Narrows by an array of formidable barriers, including Workman Road, Interstate 605, and a wide, unbroken surface of buildings and pavement. Together, these create a near total barrier to movement for all target species.

Whittier Narrows (Isolate)
Because it is functionally isolated from the Puente-Chino Hills Wildlife Corridor, I did not investigate this area in detail. Although this matrix of wetland and disturbed upland habitats probably supports some coyotes (a semi-isolated subpopulation?), it is unlikely to support other target species in perpetuity.

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Summary of Overall Corridor Function
In general, the Puente-Chino Hills Wildlife Corridor appears to be functional for at least larger mammals and birds, although tenuously so in the Missing Middle (due to several barrier roads and near barrier roads) and across smaller Segments 4 and 5 just west of the Missing Middle (due to their small size, strong edge effects, and high human and dog activity). Essentially all roads in the study area are considered barriers or at least strong filters to movements by many reptiles, amphibians, and small mammals, although most birds and larger mammals currently can move between all segments either at-grade (with mortality risks) or via critical crossing structures. Despite constraints in many locations along the corridor, target species are confirmed or highly likely to occur in all seven corridor segments, except for the coast horned lizard, which may already be absent, or will disappear in the future, west of Highway 57.

Mountain lions are capable of traversing the length of the corridor, albeit at some risk of roadkill, and one or more lions still hunt as far west as the Whittier Hills. Most other target species probably persist over the length of the corridor as metapopulations, with subpopulations segregated among geographic units by the presence of barrier or near barrier roads. These subpopulations may be linked demographically and genetically by occasional dispersal, or by within-home range movements of some individuals, depending on each species’ ability to navigate roads and crossing structures. For example, bobcats apparently have small subpopulations living in the Whittier Hills and within Segment 3 (Shell-Aera), and a larger source population living within the Chino Hills (Segments 1 and 2). Some individual bobcats probably have home ranges completely or partially within smaller segments (e.g., 4 and 5) between these more substantial habitat areas; or they occasionally move through the smaller segments, between larger ones, and thus keep the overall metapopulation interconnected demographically and genetically. This metapopulation persistence depends on both occasional cross-road movements (i.e., functional road-crossings) and sufficient patch size and habitat quality to sustain small subpopulations within segments.

Haas et al. (2002) described a gradient of declining diversity and evenness of reptile and amphibian species, moving west from the Chino Hills. This must be attributed to higher mortality and edge effects in the more fragmented portions of the study area, exacerbated by the greater distance and increasing number of barriers and filters that must be crossed as one moves farther west from source populations. This pattern of decreasing biological diversity in the western portions of the corridor is likely to be mirrored by other taxa that respond similarly to distance and barrier effects, such as small mammals. In terms of metapopulation dynamics, if a local population or subpopulation dwindles or disappears from one segment (e.g., Whittier Hills), it is less likely to be “rescued” by colonists from other segments (e.g., Chino Hills) the farther away it is from the source population and the greater the number of intervening barriers and filters. Hence, the farther west a segment lies, the greater the likelihood of local population declines or extirpations, at least for less mobile species (Haas et al. 2002).

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Table 4 summarizes the conclusions from the preceding review of geographic units and roads and presents a conceptual model of how each geographic unit (or composites of adjoining units lacking barriers) appears to function in supporting populations of target species within this segregated landscape. This table integrates diverse information, including published estimates of home ranges and densities of target species in Southern California, results of the monitoring studies summarized in Table 1, variation in habitat quality and mortality factors throughout the study area, and professional judgment. The carrying capacity estimates (in parentheses for some species) are rough approximations only, intended as order-of-magnitude estimates of the capacity of each geographic unit to support populations or subpopulations of target species, or to function as part of one or more home ranges, or to function as pass-through habitat between other units.

Where adjoining segments are considered to function as one unit for a particular target species (e.g., if individuals readily cross roads and populations are not considered segmented by them), the area of those segments is summed. Thus, Segments 1 and 2 are combined to form new Segment 1/2 (Chino-Tonner), because Carbon Canyon Road is quite permeable for most species.

Likewise, Segments 6 and 7 (the Whittier Hills) appear to serve as one contiguous geographic unit for nearly all target species, except the horned lizard, which is likely absent.

Vertical lines separating adjacent segments in Table 4 represent roads considered to segment populations for a given species. However, note that even where barrier roads do not prevent movement between adjoining segments, those segments may be treated separately in the table’s classification of segment function for a target species. For example, although the roads bounding Segment 5 are not considered mountain lion barriers, Segment 5 is rated separately as “passthrough habitat” for lions (due to small size and edge constraints), whereas Segment 4 and combined Segments 6/7 are considered foraging habitat and therefore parts of a functional home range for one or two lions that pass through Segment 5 to reach them. Similarly, although Colima Road is not a strong barrier to movement for bobcats, coyotes, or deer, narrow and edgeeffected Segments 4 and 5 likely support, at most, small subpopulations (a few resident individuals) or portions of a few individual home ranges for these species, whereas the larger and more contiguous Whittier Hills unit can support more robust and sustainable subpopulations.

By reading across the rows of Table 4 for any species, one can envision how the presence of species is maintained throughout the corridor via individual movements and metapopulation dynamics, with each segment (or combination of segments) serving as stepping stones along the way (either for an individual of a wide-ranging species like mountain lion—which may traverse the entire corridor—or over several generations for smaller species, whose individuals may move over only one or a few segments in a lifetime). For example, the only source population for mountain lions is the Santa Ana Mountains Core. The one to three resident lions that use the combined Chino-Tonner unit would not be there without this core population or the Coal Canyon Wildlife Underpass (Beier 1993, Noss et al. 1997, Haas 2000). One or more of these resident lions at least occasionally use Segment 3 (Shell-Aera) as foraging or pass-through habitat as a portion of their home range (made possible by the Tonner Bridge between Segments 2 and 3).

From there, one or more lions occasionally forage in or move through Powder Canyon (Segment 4) and San Miguel Canyon (Segment 5) to forage in the Whittier Hills (combined Segments 6/7).

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Conservation Biology Institute 33 July 2005 Table 4. Functional classification of geographic units for supporting target species populations and movements, considering effects of inter-unit barriers and filters, road-crossing structures, habitat quality, and other factors. Vertical lines indicate presence of barriers or near barriers between units for that species (names supplied for major roads). Classifications spanning multiple unit columns indicate those units are assumed to function as one for that species, using the summed size of units. Carrying capacity (numbers in parentheses) are crude estimates only, based on results of monitoring studies (see Table 1), published home range sizes and densities, habitat mosaics in each segment, and professional judgment. They are intended as order-of-magnitude estimates for the purpose of assigning functional classes, and not as precise population estimates.

Segments of the Functional Puente-Chino Hills Wildlife Corridor 1/2–Chino-Tonner 6/7–Whittier Hills
Santa Ana Mtns
Core Area 1-Chino
2-CarbonTonner 3-Shell-Aera 4-Powder- Schabarum 5-San Miguel 6-E. Whittier 7-W. Whittier Whittier
Narrows
(Isolate)
Unit Size (sq. km) 85.6 44.3 5.7 1.5 5.2 7.1 Summed Size ~2,070
129.9 13.3 7.2 12.3
~4.5
Target Species Mountain lion Pop (15-20) Subpop (1-3) HR Part (1-2) HR Part (1-2) Pass-thru HR Part (1-2) Absent Bobcat Pop (100-400) Pop (20-50) Subpop (2-10) Subpop/HR Part (2-5) Subpop (5-15) Absent? Coyote Pop (200-500) Pop (20-50) Subpop (5-12) Subpop/HR Part (2-7) Subpop (15-25) Subpop? Mule deer Pop (2,000-4,000) Pop (100-300) Subpop (10-25?) Subpop/HR Part (5-15) Subpop (15-30) Absent? Roadrunner Pop (hundreds) Pop (20-100) Subpop (?) Subpop (?) HR Part (?) Pop(?) Absent? Coast horned lizard Pop (thousands) Pop (hundreds?) Pop (hundreds?) Absent? Absent? Absent? Absent? Absent? Absent? Pop = capable of supporting a breeding population of >20 individuals and potentially serving as a source population via dispersal to other segments.

Subpop = capable of supporting 2-19 individuals as part of a metapopulation connected by at least occasional dispersal between other segments. HR Part = could comprise part of one or more individual home ranges in concert with adjoining areas, but by itself is unlikely to support a breeding pair. Pass-thru = used for movement between adjoining units, but unlikely to support individual life requisites (foraging, breeding, etc.) or a home range.

SR 57
Harbor Blvd
Colima Rd
SR 91
I- 605
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If any of the critical road crossings becomes non-functional, lions would no longer use more westerly segments, because no segments are capable of supporting a population of lions in isolation (other than the Santa Ana Mountains Core). Moreover, if any segment is reduced in size or quality to become only move-through habitat (rather than live-in habitat), the probability of lions using this unit, or any units lying further west, would drop considerably. Hence, maintaining lions in the Whittier Hills ecosystem depends not only on maintaining the possibility of unimpeded movement by individuals along the corridor, but also on maintaining substantial live-in habitat along the way.

Similarly, subpopulations in the Whittier Hills of bobcats, mule deer, roadrunners, and, to a lesser extent, coyotes exist in part due to other population or subpopulation segments (i.e., source habitats) along the corridor. Thus, the substantial habitat blocks in Segments 2 and 3 are important to continued presence of target species many kilometers away in the Whittier Hills.

Substantial reduction in the carrying capacity of any one segment increases the probability of species losses in other segments. Thus, for example, the large area of Segment 3 (Shell-Aera) is a major potential contributor to the continued presence of bobcats, mule deer, mountain lions, roadrunners, and many other species in the Whittier Hills, especially if habitat quality is increased and road crossings are improved.

To summarize, the ability of westerly segments of the corridor to support species depends both on (1) the potential for individual movement between each set of adjoining segments (a function of roads and road crossings), and (2) having sufficient live-in habitat along the way to support populations or subpopulations that contribute dispersing individuals. The greater the distance from or between source populations, the lower the probability of a habitat patch or group of patches to continue supporting that species. If the distance between occupied segments becomes too great, or if barriers prevent inter-segment movement, local extinctions are inevitable in the isolated segments. Thus, any reduction in the capacity of segments to support populations or subpopulations increases the probability of local extinctions in that segment, as well as in all other “downstream” segments to the west.

Importance of the Missing Middle to Corridor Function
This understanding of overall corridor function highlights the importance of the Missing Middle as a part of larger home ranges for more area-dependent species and for maintaining species use of segments farther west. Although there has been much attention to maintaining or improving road-crossing structures and avoiding new impediments to movement, there should be equal attention to maintaining functional habitat blocks, capable of supporting source populations of target species, within the Missing Middle. Currently, the eastern half of the Missing Middle (Tonner Canyon) serves as an extension of the large Chino-Tonner subcore, contributing dispersing individuals of target species to other segments. Likewise, Segment 3 (Shell-Aera), although somewhat smaller and degraded by grazing, undoubtedly supports significant numbers of target species that disperse (at some risk) across Harbor Boulevard into Powder Canyon and beyond.

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Future Corridor Functions
The above assessment of population distribution and movements, as summarized in Table 4, can serve as a foundation for assessing likely effects of future projects on the functionality of individual segments or the wildlife corridor as a whole. Although it is beyond the scope of this report to comprehensively analyze any particular project, I qualitatively assessed the likely effects of several proposed projects using the conceptual model presented above. I selected three proposed projects that most threaten corridor function in the Missing Middle and may eliminate wildlife populations and ecosystem functions throughout a much greater area of the Puente and Chino Hills. By impeding species movements or metapopulation dynamics within this peninsula of wild, a project’s impacts may extend far beyond its boundaries, potentially rippling through the range of hills to eliminate wildlife populations as far west as the Whittier Hills.

Shell-Aera Master Planned Community
This planned community of 3,600 homes would be scattered over most of Segment 3 and the westernmost portion of Segment 2, straddling Highway 57 and extending west to Harbor Boulevard. Although detailed development plans and environmental analyses are not yet available, I obtained the conceptual development plan shown in Figure 5. (See http://hillsforeveryone.org/PDF_Files/aera_proposal.pdf for another version of the conceptual plan, which shows additional roads and features not included on Figure 5.) Drainage 26
Tonner
Bridge
~ 1 km
Figure 5. Conceptual development plan for the Shell-Aera Master Planned Community.

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Although this conceptual plan appears to show approximately half the property as open space, it is clear that this open space represents far less than 50% of the property’s biological value, due to severe fragmentation and edge effects, disruption of movements, and elimination of live-in habitat. Much of the open space would be totally isolated between bubbles of development and roads, such as the open space bubble on the west side of Highway 57. This and other open space patches would be completely isolated from other habitat areas, removing their capacity to support target species and other native wildlife. Moreover, the narrow and highly convoluted bits of open space depicted in this plan would suffer severe edge effects, greatly reducing the area’s ability to support wildlife and ecological processes. As just one example, Argentine ants routinely invade several hundred meters from suburban edges into native scrub habitats, and even farther in moist drainages and canyons (Suarez et al. 1998). The open space bubbles are all less then 1 km across—much less in many places. Consequently, most if not all of the open space depicted in Figure 5 will be invaded by Argentine ants, which eliminate numerous native arthropods, plants, and vertebrates (such as the horned lizard) in a process of ecological collapse already well-documented in Southern California ecosystems (Suarez et al. 1998). In conclusion, only a minor fraction of remaining habitat will remain biologically useful in this proposed development area, and even that would be highly degraded relative to existing conditions.

The conceptual plan appears to be sensitive to wildlife movement needs in its depiction of a continuous “Wildlife Corridor” across the property, from Tonner Bridge through Drainage 26, to the location of the new wildlife tunnel being constructed under Harbor Boulevard. However, this characterization, apparently based on the primary movement corridor across the property as mapped by PCR (2002), is simplistic and biologically misleading. As concluded in the above review of corridor functions, long, narrow gauntlets of “move-through” habitat will not ensure continued functionality of the corridor system, which depends heavily on retaining the large blocks of live-in habitat in the Missing Middle. The mapped open-space corridor is about 4.5 km long and averages less than 500 m wide, which is insufficient to provide reliable live-in habitat for mountain lions and bobcats, for example. This is especially true considering that Segments 4 and 5 are also rather narrow and edge-effected, with marginal capacity to support foraging mountain lions or a subpopulation of bobcats. The overall result would be about 13 km of mostly linear, edge-effected, move-through habitat for these species, from live-in habitat east of Highway 57 to the next reliable foraging or subpopulation area in the Whittier Hills. The likelihood of continued movements by at least bobcats and mountain lions between Tonner Canyon and Whittier Hills would therefore drop dramatically with this development scenario.

In conclusion, this proposed housing development would seriously degrade the ability of Segment 3, and all segments farther west, to continue supporting target species, including mountain lion and bobcat. This would have cascading effects on flora and fauna in segments farther west, especially when considered in context with the relatively small and edge-effected Segments 4 and 5 it connects to on the west. Mule deer populations may, at least temporarily, increase in westerly segments like the Whittier Hills, due to removal of mountain lions from the system. In the short term, this may result in increased car-deer collisions on local roads; but in the long term, even deer are likely to disappear from all segments west of Highway 57 due to isolation of this relatively small population.

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Tres Hermanos Reservoirs
This series of three reservoirs proposed by the City of Industry in Tonner Canyon (Figure 6) would also have substantial adverse impacts on corridor function. The upper Tonner Canyon Proposed City of Industry Road
(approximate alignment)
Olinda
Landfill
SR-57
Tonner Bridge
Figure 6. Aerial photograph showing City of Industry’s proposed Tres Hermanos reservoirs and new road in Tonner Canyon.

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area (northeast of the Firestone Scout Reservation), although supporting some target species and other wildlife, is mostly open grassland and somewhat degraded in habitat quality. Although a reservoir confined to this upper area would incrementally reduce the size of this segment and its capacity to support target species populations, it is far enough removed from the primary corridor connection across the Missing Middle that it would have less effect on overall corridor function than other developments I considered. However, any development (for reservoirs or other purposes) in middle and especially lower Tonner Canyon could have severe impacts on corridor function, especially if they reduced use of the Tonner Canyon Bridge on Highway 57.

Any development that blocked access to or through the bridge area would make Highway 57 a barrier to wildlife and likely lead to wildlife extirpations in segments farther west.

At the very least, creation of these reservoirs would incrementally reduce the size of what is now a large Chino-Tonner subcore. Tonner Canyon, representing the westernmost portion of this subcore, is the primary source habitat for animals dispersing into the rest of the corridor system to the west. Hence, the location of this project would magnify its relative impact on continued corridor function by increasing the distance wildlife would have to move from source habitat areas to other segments.

Proposed City of Industry Road
Figure 6 also shows an approximate, conceptual alignment for a proposed road parallel to Tonner Canyon (see also Maps 1 and 2). Although I found no specifications for this road or associated development, it would appear to be a major throughway connecting Highway 57 (from the existing Tonner Bridge intersection) to Highway 60 across the widest portion of the PuenteChino Hills Wildlife Corridor. Based on its location, the road would require major cut and fill to construct. Perhaps most troubling is its connection at the critical Tonner Bridge wildlife undercrossing. Depending on design, this is highly likely to render this last remaining corridor connection non-functional for mountain lion, deer, bobcat, and numerous other species. Even if this connection could be engineered to retain a functional wildlife undercrossing, the road could severely impact wildlife populations and movements along a broad front. A series of additional undercrossings (or overcrossings) and extensive wildlife fencing would need to be incorporated along the length of the road, or else most of Tonner Canyon would be isolated between two barrier roads (this one and Highway 57) or wildlife would suffer severe roadkill impacts.

Approximately 21.2 sq. km of grasslands, forests, and shrublands would be segregated from the large and valuable Chino-Tonner subcore, incrementally diminishing its capacity to support wildlife populations. At best, what is now a broadly contiguous block of habitat would be reduced to a narrow and more edge-effected funnel across the Olinda Landfill to the Tonner Bridge.

Cumulative Effects
A full impact analysis for any or all of these proposed projects would need to address cumulative impacts on wildlife populations and movements through the corridor, which is beyond the scope of this report. Among these cumulative impacts would be inducement of further development, Puente-Chino “Missing Middle” Analysis
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such as additional residential, commercial, or industrial development along the road. Increased traffic (and hence roadkill) would also need to be analyzed and mitigated for. Any combination of two or more of these projects would likely render the Puente-Chino Hills Wildlife Corridor non-functional west of Olinda Landfill, regardless of mitigation.

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Discussion
Before summarizing conservation and restoration recommendations for the Missing Middle, this section reviews the literature on the functions and benefits of wildlife corridors in conservation, including criticisms of corridor conservation.

Functions and Benefits of Wildlife
Corridors
Landscape linkages and wildlife movement
corridors vaulted to the forefront of conservation
thinking in recent decades, in response to rising recognition that habitat fragmentation is a principal cause of species extinction and endangerment (Willis 1974, Diamond 1975, Wilson and Willis 1974, Noss 1983, Wilcox and Murphy 1985, Forman 1991, Harrison 1992, Rosenberg et al. 1997). Habitat connections or movement corridors connecting reserves or larger “core areas” of habitat are thought to counter many adverse effects of isolation by fragmentation on species and ecological processes (Preston 1962, Noss 1983, 1987, Soulé 1991, Meffe and Caroll 1994, Rosenberg et al. 1997, Soulé and Terborgh 1999, Beier et al. in press). Although some critics have argued that there are costs as well as benefits to conserving corridors, and that under certain circumstances creating or maintaining corridors could even harm some species or communities (e.g., Simberloff and Cox 1987, Simberloff et al. 1992, Hess 1994), the overwhelming weight of scientific evidence is that maintaining connectivity is generally beneficial, especially for those species and ecological communities for which connectivity “is the natural state of things” (Soulé and Terborgh 1999). Certainly, for most species and ecological communities, maintaining connectivity is less risky than losing connectivity (Hobbs 1992, Beier and Noss 1998, Soulé and Terborgh 1999).

Assessing Connectivity Pros and Cons
This section reviews specific arguments for and
against conserving corridors and how they apply to the
Puente-Chino Hills. As elaborated below, in most
cases, arguments against corridor conservation are
really just cautions against applying corridors as a
panacea for conservation, in recognition that there may be special cases where connecting reserves could cause more harm than good or where other approaches to conservation may be more effective or cost-effective (for example, enlarging core reserves rather than connecting existing reserves). These special cases do not apply to the Puente-Chino Hills Wildlife Corridor, where maintaining connectivity would clearly provide net benefits for biological diversity and ecosystem health in these hills. Given that the weight of scientific evidence favors connectivity here, whether and how connectivity can be assured is a societal issue not addressed in this scientific treatment. “Those who would destroy the
last remnants of natural
connectivity should bear the
burden of proving that corridor
destruction will not harm target
populations.”
Paul Beier & Reed Noss (1998)
“Connectivity is not just another
goal of conservation: it is the
natural state of things.”
Michael Soulé & John Terborgh (1999)
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The potential disadvantages of creating or maintaining wildlife movement corridors include several ecological arguments and one financial argument (Simberloff and Cox 1987, Simberloff et al. 1992, Hobbs 1992, Hess 1994):

1. Corridors may serve as conduits for the spread of deleterious species, like invasive pests, weeds, or predators.

2. Corridors may serve to spread detrimental processes—such as wildfire or disease—to or among reserve areas.6

3. Corridors may facilitate movements by highly mobile animals between reserves even without corridors. (Or, these species may be overly abundant in urban interface areas due to imbalanced ecological conditions.) But corridors may not help movement for more sedentary or at-risk species, for which other conservation approaches may work better than corridors.

4. Corridors could act as population “sinks” (Pulliam 1988), attracting individuals from higher quality habitat areas into edge-effected habitats where death rates exceed birth rates. If this effect is strong enough, it can reduce the regional abundance of the species, or even increase extinction probabilities for a rare species.

5. Corridors may be expensive to create or maintain and may not represent the optimal allocation of limited funding relative to, for example, increasing the size or management of existing core areas.

Note that in one way or another, all of these potential disadvantages hinge on relative comparisons of potential risks and benefits of maintaining vs. losing connectivity. Also, as pointed out by numerous researchers, the risks and benefits of corridors will vary by species. In the sections below, I briefly evaluate these potential disadvantages as they may apply within the Puente-Chino Hills Wildlife Corridor for target species of interest.

Conduits for Deleterious Species
It is difficult to envision how any deleterious species might increase its distribution or adverse effects due to conserving additional lands in this existing archipelago of open space reserves.

Connecting these areas with additional conservation would not increase rates with which annual weeds, Argentine ants, rats, house mice, or other potential pest species invade open space areas relative to existing conditions. Sources of such deleterious species are nearly ubiquitous in Southern California, due to existing human land use patterns. Maintaining an existing open space corridor system would not facilitate expansions of such species, either from the more urbanized western portions of the study area into the Santa Ana Mountains, or vice versa, and may even help counter further invasions (relative to more roads or development in the area).

6 Although wildfire and disease are natural disturbance processes in ecosystems, changes wrought by humans, such as habitat fragmentation and increased fire frequencies in urban interface areas, may create situations where these natural processes cause unnatural harm to biological resources. Corridors could help spread these deleterious effects.

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Conduits for Deleterious Processes
Again, it is difficult to conceive how maintaining connectivity in this context could contribute to the spread of deleterious processes. This argument is generally based on the assumption that a new corridor is being created (e.g., connecting what are naturally unconnected habitat areas) rather than maintaining “the natural state of things” with an existing, natural corridor (Beier and Noss 1998). As with the argument concerning deleterious species, this seems not to be an issue for the Puente-Chino Hills Wildlife Corridor. Although diseases or parasites may be carried between habitat segments by wildlife, this already occurs and always did. Although fires may spread from one segment to another under certain conditions, the area is already highly segmented by fire breaks in the form of existing roads and other discontinuities. In fact, given the nature of Southern California’s most destructive wildfires, which are driven by Santa Ana wind conditions (Keeley and Fotheringham 2001, Keeley et al. 1999, Halsey 2004), fire provides a stronger argument for not building more homes in wildland areas, rather than an argument for not conserving wildland areas.

Ineffectiveness for Rare or Sedentary Target Species
This is clearly a non-argument for the Puente and Chino Hills. Target species selected for review in this report, including both rare and common species, are highly sensitive to habitat fragmentation and benefit from corridor conservation (e.g., Beier 1993, Beier et al. in press, Crooks 2002, Ng et al. 2004). Although some rare or more sedentary species may not benefit directly from corridor conservation here (e.g., some reptile and amphibian species already lost from western segments of the corridor), the ecological benefits that accrue from corridor conservation for the remaining flora and fauna are indisputable. Indeed, research in the PuenteChino Hills Wildlife Corridor reinforces other research indicating that more common, insensitive, and “pesky” wildlife like skunks and raccoons actually increase in density with reductions in larger carnivores like mountain lions and bobcats, due to losses of landscape connectivity (Haas 2000, Crooks and Soulé 1999). Countering this process of “meso-predator release” (Crooks and Soulé 1999), and the cascade of species losses and other adverse ecological changes that it can bring, is a strong argument for maintaining the Puente-Chino Hills Wildlife Corridor for mountain lions, coyotes, and bobcats.

Population Sinks
This is a legitimate argument that deserves analysis. It may be that, especially for species highly prone to roadkill, mortality in the Puente and Chino Hills is elevated relative to larger, more contiguous areas like the Santa Ana Mountains. It is conceivable that the corridor therefore serves as a “population sink” (Pulliam 1988), where animals enter the corridor from larger or higher quality habitats, only to be killed. However, the potential for this effect to substantially reduce regional wildlife populations in the Santa Ana Mountains seems remote. Moreover, the benefits of these species living within the Puente and Chino Hills, even with elevated mortality rates, are immense, both to ecological health and to quality of life for local human residents.

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Suboptimal Conservation Investment
This is a non-argument for this study area. Given the current wildland-development pattern that exists, there is no alternative to corridor conservation and restoration for retaining species populations and maintaining healthy ecological processes in this area. Although one could argue that further investment in conserving these hills could be better spent elsewhere (e.g., enlarging larger wilderness reserves in Southern California mountains), this would come at the detriment of maintaining a unique ecological classroom full of wildlife in close proximity to millions of people craving a connection with nature. According to the California Department of Parks and Recreation, nearly a quarter billion dollars have already been spent on open space conservation in the Puente and Chino Hills, and this investment could be for naught if additional conservation fails to secure a continuous corridor from the Santa Ana Mountains to the Whittier Hills.

Mitigating Road Effects
Roads or the traffic they carry kill animals directly
(roadkill), disrupt natural migration and movement
patterns, interfere with species communication, change
water runoff and flow patterns, and create air, water, and soil pollution (Trombulak and Frissell 2000, Forman and Deblinger 2000, Jones et al. 2000, Reijnen et al. 1997). During Beier’s (1993, 1995) study of mountain lions in the Santa Ana Mountains, vehicles killed 33% of the population, including four lions killed at one road-crossing during a 2-year period.

The growing awareness of road impacts on environmental health and imperiled species has created a burgeoning literature on efforts to mitigate these effects with improved wildlife roadcrossing structures. Wildlife crossing structures have proved successful in the United States and elsewhere (Transportation Research Board 2002). The main types of structures, from most to least effective, are vegetated land-bridges, bridges, underpasses, and culverts.

About 50 vegetated wildlife overpasses, ranging from 50 m (164 ft) to over 200 m (656 ft) wide, have been built in Europe, Canada, and the U.S. (Evink 2002, Forman et al. 2003). Soil (0.5 to 2 m deep) covers the overpasses, which are planted, usually with native vegetation (Jackson and Griffin 2000). Overpasses are quieter than underpasses and maintain ambient conditions (Jackson and Griffin 2000), so they may be less intimidating for some species than dark tunnels.

In Banff Provincial Park, large mammals preferred overpasses to other crossing structures (Forman et al. 2003). Similarly, birds, butterflies, and other open-air wildlife are more likely to use overpasses than underpasses.

Bridges are also effective crossing structures, especially if wide enough to permit growth of both riparian and upland vegetation along stream banks (Jackson and Griffin 2000, Evink 2002, Forman et al. 2003). Bridges with greater openness ratios are generally more successful than low bridges and culverts (Veenbaas and Brandjes 1999, Jackson and Griffin 2000). The Tonner Bridge is a good example of a broad, open bridge with natural vegetation beneath. My observations reinforce those of previous biologists that maintaining access through this structure, “Nothing is worse for sensitive
wildlife than a road.”
Reed Noss
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and perhaps improving habitat conditions on either side, is critical to the flow of large mammals across the Puente-Chino Hills landscape.

Although inferior to bridges, culverts and other tunnel-like structures can be effective for some species (Jackson and Griffin 2000). Only very large culverts (such as box culverts and equestrian tunnels) are effective for large mammals (Lyren 2001, Haas 2000, Gloyne and Clevenger 2001). Gloyne and Clevenger (2001) suggest that underpasses for ungulates should be at least 4.27 m high and 8 m wide, with an openness ratio of 0.9 (where the openness ratio = height x width/length). Earthen flooring is preferable to concrete or metal (Evink 2002).

In places where a bridged, vegetated under-crossing or over-crossing is not feasible, placing pipe culverts alongside box culverts can help serve movement needs of both small and large animals.

Special crossing structures that allow light and water to enter the structure have been designed to accommodate amphibians.

Noise, artificial night lighting, traffic noise, and other disturbances can deter animal use of a crossing structure (Yanes et al. 1995, Clevenger and Waltho 1999, Forman et al. 2003). Shrub or tree cover can help funnel wildlife to a passage while hiding them or making them feel more secure when approaching crossing structures (Evink 2002, Forman et al. 2003). Regardless of crossing type, wildlife fencing is necessary to funnel animals towards road-crossing structures and keep them off the road surface (Falk et al. 1978, Ludwig and Bremicker 1983, Feldhammer et al. 1986, Haas 2000, Lyren 2001, Forman et al. 2003). Earthen one-way ramps can allow animals that wander into the right-of-way to escape over the fence (Bekker et al. 1995, Forman et al. 2003).

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Conclusions and Recommendations
Conservation and Restoration Priorities for the Missing Middle Based on the analysis of corridor function, Map 3 shows locations of priority conservation and restoration actions in and near the Missing Middle. This is by no means a comprehensive summary of all necessary and sufficient actions to maintain or improve biological conditions throughout the Puente-Chino Hills landscape. Rather, it focuses on those locations and actions that seem most critical to maintaining functional connectivity across the Puente-Chino Hills Wildlife Corridor based on the metapopulation analysis.

These recommendations are redundant with those from previous studies, especially concerning the need to secure and improve unimpeded movement by large target species across roads. This should not be surprising, because information on the characteristics and functioning of these corridor segments is quite consistent across studies. Perhaps the greatest benefit of the metaanalysis provided in this report is a renewed focus on the need to conserve not just unimpeded movement, but an archipelago of relatively large habitat blocks with sufficient carrying capacity to ensure continued presence of viable populations through this range of hills. Road-crossings are just one part of the story.

Priority Conservation Lands
Conserving intact habitat blocks within the red-hatched lands on Map 3 is essential to maintaining functional metapopulation dynamics for target species throughout the Puente-Chino Hills Wildlife Corridor. As supported by the geographic unit analysis, the capacity of Segments 2 and 3—from Chino Hills State Park to Harbor Boulevard—to support robust populations of target species and live-in habitat for mountain lions is essential to keeping these species in the study area, all the way to Whittier Hills. Essentially all of the Shell-Aera property, and at least the lower 1/2 to 2/3 of the City of Industry lands in Tonner Canyon, are of high priority for conservation.

Note that the line separating high-priority conservation lands in mid- to lower Tonner Canyon from upper Tonner Canyon is somewhat arbitrary. But the farther up Tonner Canyon one goes, the less essential habitat becomes for ensuring corridor functionality. (Note, however, that Cooper [2000] considered upper Tonner Canyon a high conservation priority for native birds, especially grassland species like raptors and grasshopper sparrows.) I established the northeast boundary of the Tonner Canyon high-priority conservation area primarily to consolidate a contiguous reserve along with the existing Firestone Scout Reservation and Chino Hills State Park. Extending this boundary farther north would increase biological benefits even more, but with decreasing marginal returns for corridor function.

Conservation Biology Institute 46 July 2005
Map 3. Conservation and restoration priorities in the vicinity of Missing Middle.

Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute 47 July 2005
Essentially all of the Shell-Aera property west of Highway 57 is extremely high priority for conserving corridor integrity. Based on metapopulation analysis, conserving a “move-through corridor” across this property, as depicted in Figure 5, is not enough to ensure continued target species presence through the corridor system. Given this segment’s location between two nearbarrier roads, and the relatively narrow and constrained status of Segments 4 and 5 to the west, securing a large, intact habitat block capable of supporting populations or subpopulations of target species is essential here. Moreover, this segment could benefit greatly from habitat management and restoration to increase carrying capacity for target species, and thereby to decrease the probability of species extirpations here and all the way to the Whittier Hills.

Priority Crossing Improvements
Map 3 shows five priority road-crossing improvements with magenta circles, labeled A through E from east to west. Most of these recommendations have already been made by others (e.g., Haas 2000), and some may already have been acted on or are in planning stages. At the risk of redundancy, I nevertheless recommend the following improvements in these general locations.

Refer to Haas (2000) for additional recommendations and details:

A. Add wildlife fencing on either side of Carbon Canyon Road to reduce roadkill and encourage wildlife to use existing culverts, especially the concrete box culvert near the entrance to Chino Hills State Park. Adding another wildlife crossing structure, designed to accommodate all large mammals, would be even better. Given that traffic on this 2- lane road is increasing due to increasing development in the vicinity (Haas 2000), any future road upgrades should incorporate bridges or other very open wildlife crossing structures as mitigation. A variety of smaller under-crossings with funneling fences, specifically designed to accommodate smaller reptiles, amphibians, and mammals, should also be considered to improve connectivity for these species.

B. Prohibit any development that would increase traffic under the Tonner Bridge or add any new impediments (structures, lights, noise, etc.) to the vicinity of the bridge. Restore riparian vegetation along Tonner Creek, where degraded by oil development activities.

Fence along Highway 57 if monitoring suggests road mortality is high.

C. A wildlife underpass tunnel is to be constructed here under Harbor Boulevard, but recommended fencing has apparently not been allowed by a property owner (A.

Henderson, personal communication). Secure rights to install wildlife fencing along both sides of Harbor Boulevard to reduce roadkill and ensure maximum utility of the wildlife tunnel. Plant native shrubs and trees on either side of the tunnel to provide cover to wildlife approaching the entrances. Consider adding smaller under-crossings and funneling fences to accommodate smaller reptiles, amphibians, and mammals.

D. Secure remaining “at-risk” parcels in this narrow, constricted portion of the corridor, west of Powder Canyon and Schabarum Regional Park. Enlarge or otherwise improve the existing equestrian tunnel to enhance its use by wildlife, including adding screening Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute 48 July 2005
vegetation, especially on the western end. Fence either side of the tunnel to help funnel wildlife to it. However, extensive fencing along Hacienda Boulevard is not recommended, because most large mammals currently cross at-grade. Although Hacienda Boulevard currently has moderate traffic at relatively low speeds, and therefore relatively low roadkill (Haas 2000), road improvements or increases in traffic could make the situation worse. In this case, consider building a wildlife overpass (a vegetated wildlife bridge) over Hacienda Boulevard, taking advantage of steep slopes rising up from either side of the road. Given this terrain, a vegetated overpass somewhere between Skyline Drive and the equestrian tunnel may be feasible and would certainly be superior to culverts or other underpass structures in accommodating wildlife movement. Consider also adding smaller under-crossings and funneling fences to accommodate smaller reptiles, amphibians, and mammals.

E. Maintain and improve the Colima Service Tunnel as a critical wildlife underpass. Add fencing or screening vegetation, if necessary, based on further site-specific inspection or monitoring. Limit and mitigate for any actions that may increase traffic, light, noise, or human activity in the vicinity of the Service Tunnel from sunset to sunrise, when wildlife use is most frequent. Consider also adding smaller under-crossings and funneling fences to accommodate smaller reptiles, amphibians, and mammals.

Puente-Chino “Missing Middle” Analysis
Conservation Biology Institute 49 July 2005
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Attachment D. Revised Appendix E Biological Resources Technical Report
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Biological Resources
Technical Report
Brea 2050: Focused General Plan Update and
Brea Core Specific Plan Project
April 2026
Prepared for:

City of Brea
Community Development Department, Planning Division
1 Civic Center Circle,
Brea, California, 92821.

Prepared by:

Harris & Associates
2375 Northside Drive, Suite 125
San Diego, California 92108

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Biological Resources Technical Report i April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Table of Contents
Acronyms and Abbreviations .................................................................................................... v Executive Summary.................................................................................................................... 1 Section 1 Introduction ............................................................................................................ 1

1.1 Project Description .......................................................................................... 1

1.1.1 Project Location ................................................................................... 1

1.2 Purpose ........................................................................................................... 2

1.3 Environmental Setting ..................................................................................... 2

1.3.1 Land Use ............................................................................................. 2

1.3.2 Topography and Soils.......................................................................... 2

1.3.3 Hydrology............................................................................................. 3

1.3.4 Climate................................................................................................. 3 Section 2 Methods................................................................................................................... 5

2.1 Literature Review............................................................................................. 5

2.2 Vegetation Mapping......................................................................................... 5 Section 3 Results .................................................................................................................... 7

3.1 Vegetation Communities and Land Cover Types ............................................ 7

3.1.1 Vegetation Communities...................................................................... 8

3.1.2 Land Cover Types .............................................................................11

3.2 Jurisdictional Wetlands and Waters ..............................................................12

3.3 Sensitive Plant and Wildlife Species .............................................................13

3.3.1 Sensitive Plant Species .....................................................................13

3.3.2 Sensitive Wildlife Species..................................................................16

3.3.3 Critical Habitat ...................................................................................24

3.3.4 Nesting Birds .....................................................................................25

3.3.5 Sensitive Roosting Bats.....................................................................25

3.4 Wildlife Corridors and Habitat Linkages ........................................................26 Section 4 Regulatory Framework ........................................................................................28

4.1 Federal ..........................................................................................................28

4.2 State ..............................................................................................................29

4.3 Local..............................................................................................................30

4.3.1 City of Brea General Plan ..................................................................30

4.3.2 Orange County Transportation Authority Habitat Conservation Plan (HCP)/Natural Community Conservation Plan (NCCP) Planning Agreement .........................................................................................32 Section 5 Thresholds of Significance .................................................................................34 Section 6 Impacts..................................................................................................................36 Biological Resources Technical Report ii April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project

6.1 Threshold 1: Sensitive Plant and Wildlife Species ........................................36

6.1.1 Guidelines for Determination of Significance.....................................36

6.1.2 Impacts Analysis................................................................................37

6.1.3 Mitigation Measures...........................................................................42

6.1.4 Significance After Mitigation ..............................................................48

6.2 Threshold 2: Riparian Habitat or Other Sensitive Natural Community ..........54

6.2.1 Guidelines for Determination of Significance.....................................54

6.2.2 Impact Analysis..................................................................................55

6.2.3 Mitigation Measures...........................................................................56

6.2.4 Significance After Mitigation ..............................................................56

6.3 Threshold 3: Jurisdictional Aquatic Resources..............................................56

6.3.1 Guidelines for Determination of Significance.....................................56

6.3.2 Impact Analysis..................................................................................56

6.3.3 Mitigation Measures...........................................................................57

6.3.4 Significance After Mitigation ..............................................................58

6.4 Threshold 4: Wildlife Corridors and Habitat Linkages ...................................58

6.4.1 Guidelines for Determination of Significance.....................................58

6.4.2 Impact Analysis..................................................................................59

6.4.3 Mitigation Measures...........................................................................60

6.4.4 Significance After Mitigation ..............................................................60

6.5 Threshold 5: Local Policies and Ordinances .................................................60

6.5.1 Guidelines for Determination of Significance.....................................60

6.5.2 Impact Analysis..................................................................................60

6.5.3 Mitigation Measures...........................................................................61

6.5.4 Significance After Mitigation ..............................................................61

6.6 Threshold 6: Regional Conservation Planning ..............................................61

6.6.1 Guidelines for Determination of Significance.....................................61

6.6.2 Impact Analysis..................................................................................61

6.6.3 Mitigation Measures...........................................................................62

6.6.4 Significance After Mitigation ..............................................................62

6.7 Cumulative Impacts .......................................................................................62

6.7.1 Cumulative Threshold 1: Sensitive Plant and Wildlife Species..........62

6.7.2 Cumulative Threshold 2: Riparian Habitat or Other Sensitive Natural Community ............................................................................62

6.7.3 Cumulative Threshold 3: Jurisdictional Aquatic Resources...............63

6.7.4 Cumulative Threshold 4: Wildlife Corridors and Habitat Linkages.....63

6.7.5 Cumulative Threshold 5: Local Policies or Ordinances .....................64

6.7.6 Cumulative Threshold 6: Regional Conservation Planning ...............64 Section 7 References ............................................................................................................66 Biological Resources Technical Report iii April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Tables
Table 1. Vegetation Communities and Land Cover Types in the Project Area............................. 7 Table 2. Sensitive Plant Species Documented in the Project Area ............................................13 Table 3. Sensitive Wildlife Species Documented in the Project Area .........................................17 Appendices
Appendix A. Figures
Biological Resources Technical Report iv April 2026
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Biological Resources Technical Report v April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Acronyms and Abbreviations
amsl above mean sea level
BMP best management practice
BCSP Brea Core Specific Plan
BIOS Biogregraphic Information Observation System
CCE California candidate endangered species
CDFW California Department of Fish and Wildlife
CE California endangered
CEQA California Environmental Quality Act
CFGC California Fish and Game Code
City City of Brea
CRPR California Rare Plant Rank
CT California threatened
CWA Clean Water Act
FE federally endangered
FT federally threatened
GIS geographic information system
IPaC Information for Planning and Consultation
MBTA Migratory Bird Treaty Act
MCV Manual of California Vegetation
NCCP Natural Community Conservation Planning
NPDES National Pollutant Discharge Elimination System
PEIR Program Environmental Impact Report
Porter-Cologne Act Porter-Cologne Water Quality Control Act Project Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project
RWQCB Regional Water Quality Control Board
SR- State Route
SSC species of special concern
USACE U.S. Army Corps of Engineers
USFWS U.S. Fish and Wildlife Service
WL California Department of Fish and Wildlife watch list Biological Resources Technical Report vi April 2026
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Biological Resources Technical Report ES-1 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Executive Summary
At the request of the City of Brea (City), Harris & Associates has prepared this Biological Resources Technical Report for the Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project (Project) Program Environmental Impact Report (PEIR).

The Project aims to update the 2003 Brea General Plan, specifically the Community Development (land use, circulation, economic development), Community Resources (open space), Community Services (recreation, education, cultural arts), and Public Safety chapters. At the time of its preparation, the 2003 Brea General Plan was based on forecasting and projections with a horizon year of 2020. Therefore, it is no longer a visioning document for the community and requires an update. The Focused GPU would allow for additional housing units and non-residential square footage across various land use categories within the incorporated City limits and would continue to allow for limited housing units in the unincorporated sphere of influence, consistent with the 2003 Brea General Plan.

This report presents the documented biological resources known to occur in the project area; identifies potential impacts to sensitive biological resources; documents potential jurisdictional aquatic resources; and recommends avoidance, minimization, or mitigation measures consistent with federal, state, and local rules and regulations.

The biological resources impacts analysis was prepared in accordance with the California Environmental Quality Act (CEQA) of 1970 and the CEQA Guidelines (as amended). This report is a technical study in support of the PEIR.

The biological resources documented as present or with potential to occur in the project area were identified through a review of existing maps, literature and other biological studies conducted in the area, and sensitive species occurrence databases. No biological survey, field reconnaissance, aquatic resources delineation, or focused species surveys were conducted as a part of this project.

The results of this review provide information on the potential constraints to Project development due to the presence of sensitive biological resources.

Eight vegetation communities and three land cover types are documented within the Project area.

The vegetation communities include fresh water, freshwater emergent wetland, non-vegetated channel, cismontane woodland, riparian forest/scrub, annual grassland, chaparral, and coastal scrub, all of which are considered sensitive. The three land cover types include agriculture, disturbed, and urban/developed land, none of which are considered sensitive.

A total of ten sensitive plant species and 20 sensitive wildlife species have been documented in the Project area. Critical habitat for one sensitive wildlife species occurs in the Project area.

Biological Resources Technical Report ES-2 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Project implementation would result in potentially significant direct and indirect impacts to sensitive plant and wildlife species (including nesting birds and raptors, sensitive roosting bats, and critical habitat), sensitive vegetation communities, jurisdictional aquatic resources, and wildlife corridors and habitat linkages. Impacts resulting from conflicts with local policies, ordinances, or regional conservation plans protecting biological resources would be less than significant.

Implementation of Mitigation Measures BIO-1 through BIO-4 would reduce direct and indirect Project impacts to the sensitive plant species with potential to occur and their critical habitat to below a level of significance.

Implementation of Mitigation Measures BIO-3 through BIO-7 would reduce direct and indirect Project impacts to the sensitive wildlife species with potential to occur and their critical habitat to below a level of significance. Further, direct and indirect impacts to sensitive nesting birds and raptors and sensitive roosting bats would be mitigated to below a level of significance with implementation of Mitigation Measures BIO- 3 through BIO-7.

Implementation of Mitigation Measures BIO-3 and BIO-5 would reduce direct and indirect impacts to sensitive vegetation communities to below a level of significance.

Implementation of Mitigation Measures BIO-3 through BIO-5, BIO-8, and BIO-9 would reduce direct and indirect impacts to potentially jurisdictional aquatic resources to below a level of significance.

Implementation of Mitigation Measures BIO-3 through BIO-6 would reduce direct and indirect impacts to wildlife movement corridors and habitat linkages to below a level of significance.

No Habitat Conservation Plan or NCCP Plan has been adopted in or adjacent to the Project area.

Therefore, no impacts to local conservation plans would occur from the implementation of the Project.

Implementation of the Project would not result in cumulative impacts to biological resources because impacts would be reduced to below a level of significance with implementation of Mitigation Measures BIO-1 through BIO-9.

Biological Resources Technical Report 1 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Section 1 Introduction
This Biological Resources Technical Report (BRTR) for the proposed Brea 2050: Focused General Plan Update (Brea 2050 or Focused GPU) and Brea Core Specific Plan (BCSP) Project (Project) Program Environmental Impact Report (PEIR) documents the biological resources in the City of Brea and its Sphere of Influence (SOI) and addresses at a programmatic level the potential biological resources impacts associated with the construction and operation of the Project for the City of Brea. Note that the City of Brea, as a governmental entity, is referred to as the “City,” while the geographical area of the incorporated City of Brea is referred to as the “city.”

1.1 Project Description
The purpose of the Focused GPU is to create a policy framework that outlines the City’s long-term physical form and development while preserving and enhancing the quality of life for the City’s residents. The Focused GPU seeks to adapt the 2003 Brea General Plan, specifically the Community Development (land use, circulation, economic development), Community Resources (open space), Community Services (recreation, education, cultural arts), and Public Safety chapters, with an emphasis on the land use and circulation components. At the time of its preparation, the 2003 Brea General Plan was based on forecasting and projections with a horizon year of 2020. As such, it is no longer a visioning document for the community and requires an update. The Focused GPU would allow for additional housing units and non-residential square footage across various land use categories within the incorporated City limits and would continue to allow for limited housing units in the unincorporated sphere of influence, consistent with the 2003 Brea General Plan.

The Project also includes a new specific plan, Brea Core Specific Plan (BCSP), which would implement the values identified in the 2017 Brea Envisions and the goals, policies, and recommendations of the 2020 Core Active Transportation Plan. The BCSP would establish land uses, provide mobility recommendations and streetscape improvements, propose infrastructure upgrades to support proposed development, and outline implementation strategies for the BCSP area. The BCSP would also allow for the development of 4,752 residential units and 6,379,588 square feet of non-residential uses within the BCSP area.

1.1.1 Project Location
The Project area includes the incorporated City of Brea and its Sphere of Influence (SOI), collectively referred to as the Project area, and is located within northeastern Orange County, California. The city is bordered by unincorporated Orange County land and the Los Angeles County line to the north; Chino Hills State Park and the San Bernardino County line to the east; the Cities of Yorba Linda, Placentia, and Fullerton to the south; and the City of La Habra to the west (Appendix A, Figures; Figure 1, Regional Location and Figure 2, Project Area). The Project Biological Resources Technical Report 2 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project area encompasses approximately 22.6 square miles and is composed of diverse natural habitats and residential communities.

The Project area also includes the BCSP area, located in the southwestern portion of the City. The BCSP is generally bounded by Lambert Road to the north, Imperial Highway (SR-90) to the south, Berry Street to the west, and SR-57 and Associated Road to the east.

1.2 Purpose
At the request of the City, Harris & Associates has prepared this Biological Resources Technical Report for the Project. The purpose of this Biological Resources Technical Report is to present documented biological resources known to occur in the Project area; identify potential impacts to sensitive biological resources; document potential jurisdictional aquatic resources; and recommend avoidance, minimization, or mitigation measures consistent with federal, state, and local rules and regulations.

1.3 Environmental Setting
The following is a description of the existing conditions in the Project area.

1.3.1 Land Use
The Project area is largely developed, and contains various residential, commercial, and industrial development. Various parks/recreation spaces are scattered throughout the Project area, and large areas of open space occur in the hills to the east of Valencia Avenue (SR-142). Other uses include cemetery, public facilities, and mixed use.

1.3.2 Topography and Soils
The City of Brea is bounded to the north and east by the lower Transverse Ranges, near the boundary of eastern Los Angeles County. The northern and eastern portions of the City generally contain gently to moderately steep slopes and ridges, and the unincorporated Sphere of Influence area contains primarily steep slopes and ridges. To the south and west, within the City, the topography is generally flat, forming part of the Coastal Plain of Orange County (Figure 3, USGS Topographic Map). Elevation in the City ranges from approximately 350 to 1,200 feet above mean sea level (amsl), while the elevation in the sphere of influence ranges from approximately 450 to 1,325 feet amsl. The Project area lies within several quadrangles of the California Geological Survey Map, including Prado Dam, La Habra, and Yorba Linda Quadrangles.

A total of 40 soil types are present in the Project area, including Alo clay, Alo variant clay, Anaheim clay loam, Anaheim loam, Apollo warm-Calleguas complex, Balcom clay loam, Blasingame-rock outcrop complex, Bosanko clay, Calleguas clay loam, Capistrano sandy loam, Cieneba sandy loam – eroded, Cieneba-Friant sandy loams complex, Cieneba-rock outcrop complex, Cropley clay, dam, Fontana clay loam, Gaviota-Chumash-rock outcrop complex, Marina Biological Resources Technical Report 3 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project loamy sand, Metz loamy sand, Mocho loam, Myford sandy loam, Myford sandy loam - eroded, Myford sandy loam – thick surface, Nacimiento clay loam, Omni clay, Rincon clay loam, riverwash, rock outcrop-Cieneba complex, San Emigdio fine sandy loam, Soper cobbly loam, Soper gravelly loam, Soper loam, Soper-rock outcrop complex, Sorrento clay loam, Sorrento loam, water, Xeralfic arents – loamy, Xerorthents loamy - cut and fill areas, Yorba cobbly sandy loam, and Zaca-Apollo - warm complex (Figure 4, Soils; USDA 2025a; USDA 2025b).

1.3.3 Hydrology
The Project area occurs within two watersheds, Coyote Creek watershed and the Santa Ana River watershed (H2OC Stormwater Program 2025). Together, these watersheds cover approximately 252 acres of land, and occur in Orange, San Bernardino, and Los Angeles counties. Both watersheds capture flows which drain west into the Pacific Ocean. The primary waterways in these watersheds include the Coyote Creek, Brea Creek, Fullerton Creek, Santiago Creek, and the Santa Ana River. Irvine lake, a reservoir located in Silverado, California, is present in the Santa Ana River Watershed.

Figure 5, Hydrology, identifies the major hydrologic features documented in the vicinity of the Project area (USFWS 2025a; USGS 2025). Of the major hydrologic features documented in the region, the Santa Ana River is defined as traditional navigable waters by the U.S. Army Corps of Engineers (USACE) and is located immediately south and southwest of the Project area (USACE 2025). Many of the other rivers and streams, as well as numerous creeks and drainages, are tributary to these traditional navigable waters or have direct connections to the Pacific Ocean.

1.3.4 Climate
On a regional level, the Project area has a Mediterranean climate, which is characterized by wet winters and warm, dry summers Habitats in this region include both mesic (moist) habitats and xeric (dry) habitats. Generalized climate in the region is characterized by warm, dry summers and cold, moist winters, which pushes the growing season to the wet months of the year (late winter to early spring). Vegetation often goes dormant (senescent) during the later summer months until initial rains start in the late fall. The rainy season in the Project area typically lasts from November through April and has an annual winter precipitation average of approximately 14 inches (Western Regional Climate Center 2025).

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Biological Resources Technical Report 5 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Section 2 Methods
Biological resources documented as present or with potential to occur in the Project area were identified through a review of existing maps, literature and other biological studies conducted in the area, and sensitive species occurrence databases. No biological survey, field reconnaissance, aquatic resources delineation, or focused species surveys were conducted as a part of this Project.

The results of this review provide information on the potential constraints to Project development due to the presence of sensitive biological resources. The potential presence of critical habitat in the Project area was also analyzed.

2.1 Literature Review
The following documents and databases were reviewed
• Calflora Database (Calflora 2025)
• Consortium of California Herbaria database (CCH 2025) • The CNPS Rare Plant Program Inventory of Rare Plants (CNPS 2025) • California Natural Diversity Database (CDFW 2025a)
• CDFW Biogeographic Information and Observation System (CDFW 2025b) • U.S. Department of Agriculture Soil Survey (USDA 2019) • USFWS Information for Planning and Consultation (IPaC) (USFWS 2025b) • USFWS NWI Wetlands Mapper (USFWS 2025a)
• USGS National Hydrography Dataset (NHD) (USGS 2025)

2.2 Vegetation Mapping
Vegetation community boundaries for the Project area were obtained in geographic information system (GIS) format from the California Department of Fish and Wildlife (CDFW) Biogeographic Information and Observation System (BIOS) (CDFW 2025b). Approximately 21 acres of land was not mapped in the BIOS database and was extrapolated based on aerial imagery.

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Biological Resources Technical Report 7 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Section 3 Results
The results presented in this section provide data from the literature and database review conducted for the Project area. For the purposes of this Biological Resources Technical Report, sensitive biological resources are those defined as follows: (1) species designated as endangered, threatened, rare, protected, sensitive, or species of special concern according to the U.S. Fish and Wildlife Service (USFWS), California Department of Fish and Wildlife (CDFW), California Native Plant Society (CNPS), or applicable regional plans, policies, or regulations needs due to limited distribution, limited numbers, or significant population declines associated with natural or humanmade causes; (2) species and habitat types recognized by local and regional resource agencies as special status; (3) habitats or vegetation communities that are unique, are of relatively limited distribution, or are of particular value to wildlife; or are identified as sensitive in regional or local plans, policies, or regulations, or by the USFWS or CDFW (4) wildlife corridors and habitat linkages; or (5) biological resources that may or may not be considered special status but are regulated under local, state, or federal laws.

3.1 Vegetation Communities and Land Cover Types
Vegetation community types are categorized into general overarching habitat categories under which the Manual of California Vegetation (MCV) alliances (Sawyer et. al. 2009) are described.

Alliances listed in the Project area are based on the U.S. National Vegetation Classification System (USNVC) data reported by BIOS. The Project area consists of eight habitats and three land cover types, including fresh water, freshwater emergent wetland, non-vegetated channel, cismontane woodland, riparian forest/scrub, annual grassland, chaparral, coastal scrub, agricultural land, disturbed land, and urban/developed land (Table 1). The eight vegetation communities documented in the Project area include MCV alliances with vegetation associations that are considered sensitive by CDFW (2025c). Other vegetation communities may be considered sensitive because impacts to these habitats are often regulated by the USFWS, CDFW, USACE, or Regional Water Quality Control Board (RWQCB). The three land cover types, agricultural land, disturbed land, and urban/developed land, are not considered sensitive.

The following sections describe the documented vegetation communities and land cover types in the Project area. These are summarized in Table 1, Vegetation Communities and Land Cover Types in the Planning Area and illustrated in Figure 6, Vegetation and Land Cover Types.

Table 1. Vegetation Communities and Land Cover Types in the Project Area Vegetation Community and Land Cover Type Acres
Wetlands and Waters
Fresh Water1 14.40
Freshwater Emergent Wetland1 35.81
Non-Vegetated Channel1 25.01
Biological Resources Technical Report 8 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Table 1. Vegetation Communities and Land Cover Types in the Project Area Vegetation Community and Land Cover Type Acres
Riparian Forest/Scrub1 604.04
Upland Habitats
Cismontane Woodland1 886.77
Grassland
Annual Grassland1 2,042.30
Chaparral and Scrub
Chaparral1 789.74
Coastal Scrub 1 1,728.22
Developed
Agricultural Land 106.68
Disturbed Land 2,705.03
Urban/Developed Land 5,578.52
Sources: CDFW 2025b.

Notes:
1 Associated with MCV alliances that contain sensitive vegetation associations.

3.1.1 Vegetation Communities

3.1.1.1 Wetlands and Waters
Fresh Water
Fresh water, which is typically an unvegetated habitat, includes year-round bodies of fresh water in the form of lakes, streams, ponds, or rivers. This includes those portions of water bodies that are usually covered by water and contain less than 10 percent vegetated cover. BIOS did not report any specific MCV alliances associated with fresh water.

Approximately 14.40 acres of fresh water occur within the Project area (Figure 6). Fresh water may fall under the regulatory jurisdiction of the USACE, USFWS, RWQCB, or CDFW.

Freshwater Emergent Wetland
Freshwater emergent wetlands are generally persistent wetlands dominated by low-growing, perennial wetland species and can be found in channels, seeps, and springs; floodplains; margins of lakes and rivers; and various basins such as pools and ponds, palustrine lakes, montane meadows, and dune swales. BIOS did not report any specific MCV alliances associated with freshwater emergent wetland.

Approximately 35.81 acres of freshwater emergent wetland occurs along documented aquuatic resources within the Project area (Figure 6). Freshwater emergent wetland has the potential to fall under the regulatory jurisdiction of the USACE, USFWS, RWQCB, or CDFW.

Biological Resources Technical Report 9 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Non-Vegetated Channel
Non-vegetated channel consists of predominantly sandy, gravelly, or rocky channels lacking or with reduced vegetation. Variable water lines inhibit the growth of vegetation, although some weedy species of grasses may grow along the outer edges of the channel. Vegetation may exist here but is usually less than 10 percent of the total cover. BIOS did not report any specific MCV alliances associated with non-vegetated channel.

Approximately 25.01 acres of non-vegetated channel occur in the Project area. Non-vegetated channel can be found along numerous streams and drainages that occur throughout the Project area (Figure 6), and has the potential to fall under the regulatory jurisdiction of the USACE, USFWS, RWQCB, or CDFW.

Riparian Forest/Scrub
Riparian forest and scrub communities documented in the Project area are associated with the MCV Sambucus nigra (black elderberry) alliance, Baccharis salicifolia (mulefat) alliance, Salix lasiolepis (arroyo willow) alliance, Salix gooddingii (Goodding’s willow) alliance, and Platanus racemosa (Western sycamore) alliance. All of these alliances include MCV vegetation associations that are considered sensitive (CDFW 2025c). Baccharis salicifolia alliances are shrub communities dominated or co-dominated by mulefat. They contain two canopy tiers, with heights of 2 meters and 5 meters, and sparse understories. Salix lasiolepis alliances are riparian shrub communities dominated or co-dominated by arroyo willow. They grow up to 10 meters in height, and canopies are open to continuous. Understories are variable. Salix gooddingii alliances are woodlands dominated or co-dominated by Goodding’s willow. Canopy heights reach up to 30 meters, and are open to continuous. Shrub layers are sparse to continuous, and understories are variable. Platanus racemosa alliances are riparian woodlands dominated or co-dominated by western sycamore. Canopies are open to intermittent and reach heights up to 35 meters. The shrub layer is open to intermittent, and understories are sparse or grassy.

Approximately 604.04acres of riparian forest/scrub occurs in the Project area, primarily in the eastern portion (Figure 6). The riparian forest/scrub in the Project area may fall under the regulatory jurisdiction of the CDFW.

3.1.1.2 Upland Habitats
Cismontane Woodland
Cismontane woodland documented in the Project area is associated with the MCV Juglans californica (California black walnut) alliance and the Quercus agrifolia (coast live oak) alliance, both of which contain MCV vegetation associations that are considered sensitive (CDFW 2025c). Juglans californica alliances are woodlands dominated or co-dominated by California black walnut, with canopy heights up 15 meters tall, open to continuous canopies, sparse to intermittent shrub layers, and a sparse or Biological Resources Technical Report 10 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project grassy understory. Quercus agrifolia alliances are upland woodlands dominated or co-dominated by coast live oak. These woodlands grow up to 30 meters tall, with open to continuous canopies, sparse to intermittent shrub layers, and sparse or grassy understories.

Approximately 886.77 acres of cismontane woodland occurs in the Project area, primarily in the northern and eastern portions (Figure 6).

Annual Grassland
Generally, annual grasslands are dominated by annual grasses and forbs. Grass species may be native or non-native, but are generally dominated by oat (Avena sp.), red brome (Bromus rubens), ripgut brome (Bromus diandrus), barley (Hordeum sp.) and mustard (Brassica sp.). BIOS did not report any specific MCV alliances associated with annual grassland documented in the Project area.

Approximately 2,042.30 acres of annual grassland occurs in the Project area, primarily along moderate to steeply sloped hillsides in the northern and eastern portions of the Project area (Figure 6).

Chaparral
Chaparral documented in the Project area is associated with the MCV Quercus berberidifolia (Scrub oak) alliance and Heteromeles arbutifolia (Toyon) alliance, both of which include MCV vegetation associations that are considered sensitive (CDFW 2025c). Quercus berberidifolia alliances are shrub communities dominated or co-dominated by scrub oak. They grow to heights of 6 meters, and have continuous canopies. The understories are sparse. Heteromeles arbutifolia alliances are shrub communities dominated or co-dominated by toyon, and grow to heights of up to 15 meters.

The canopies are open to continuous, and understories are sparse to continuous. Approximately 789.74 acres of chaparral occurs in the Project area, primarily along steep hillsides in the northern and eastern portions of the Project area (Figure 6).

Coastal Scrub
Coastal scrub documented in the Project area is associated with the MCV Opuntia littoralis (Coast prickly pear) alliance, Artemisia californica (California sagebrush) alliance, Malosma laurina (laurel sumac) alliance, Eriogonum fasciculatum (California buckwheat) alliance, Atriplex lentiformis (big saltbush) alliance, Salvia mellifera (black sage) alliance, Artemisia californica - Salvia mellifera alliance, and Artemisia californica - Eriogonum fasciculatum alliance. All alliances, except the Salvia mellifera alliance, include MCV vegetation associations that are considered sensitive, (CDFW 2025c). Opuntia littoralis alliances are shrub communities dominated or co-dominated by coast prickly pear. Canopies are intermittent or continuous and occur in two tiers, with heights up to two meters. The understories are continuous and diverse.

Artemisia californica alliances are shrub communities co-dominated by California sagebrush.

Artemisia californica alliances may contain one or two tiers, reaching 2 meters to 5 meters tall.

Biological Resources Technical Report 11 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Canopies are intermittent to continuous, and understories are variable both seasonally and annually. Malosma laurina alliances are shrub communities dominated or co-dominated by laurel sumac. They grow up to five meters tall, and have open to continuous canopies.

Understories are sparse or grassy. Eriogonum fasciculatum alliances are shrub communities dominated or co-dominated by California buckwheat. Shrubs reach up to two meters, and canopies are continuous or intermittent. Understories are variable and may be grassy. Atriplex lentiformis alliances are shrub communities dominated by big saltbush. They consist of open to intermittent canopies reaching heights of up to 5 meters. The understories are variable. Salvia mellifera alliances are shrub communities dominated or co-dominated by black sage. Salvia mellifera alliances may contain one or two tiers, reaching up to 2 meters tall. Canopies are intermittent to continuous, and understories are variable; grasses and herbs are seasonal.

Artemisia californica - Salvia mellifera alliances are shrub communities co-dominated by California sagebrush and black sage with a relatively open canopy. The understories are welldeveloped. Artemisia californica - Eriogonum fasciculatum alliances are shrub communities codominated by California sagebrush and California buckwheat. The canopy may be one or twotiered, with heights of two to five meters, and ranging from intermittent to continuous in coverage. Understories are well-developed.

Approximately 1,728.22 acres of coastal scrub occurs in the Project area, primarily along steep hillsides in the northern and eastern portions of the Project area (Figure 6).

3.1.2 Land Cover Types
Agricultural Land
Agricultural land is not considered a vegetation community, therefore BIOS did not report any MCV alliances associated with agricultural land Agricultural land includes areas occupied by dairies and livestock feed yards or areas that have been tilled for use as croplands or groves and orchards.

Approximately 106.68 acres of agricultural land occurs primarily in the central and southern portions of the Project area (Figure 6). The agricultural land in the Project area is primarily composed of vineyards, fruit orchards, and grain crops.

Disturbed Land
Disturbed land is not considered a vegetation community, therefore BIOS did not report any MCV alliances associated with disturbed land Disturbed land consists of previously disturbed areas that either are devoid of vegetation (dirt roads/trails) or support scattered non-native plant species, such as ornamentals or ruderal exotic species, that take advantage of disturbance, such as black mustard (Brassica nigra), short-pod mustard (Hirschfeldia incana), and Erodium species. These species are non-native and typically found in disturbed habitats, particularly in areas that have been graded, Biological Resources Technical Report 12 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project repeatedly cleared for fuel management purposes, and/or experienced repeated use that prevents natural revegetation.

Approximately 2,705.03 acres of disturbed land occurs in the Project area. Disturbed land primarily consists of barren hillsides located in the eastern portion of the Project area (Figure 6).

Urban/Developed Land
Urban/developed land is not considered a vegetation community, therefore BIOS did not report any MCV alliances associated with urban/developed land. (Holland 1986). Urban/developed land represents areas that have been constructed on or otherwise physically altered to an extent that native vegetation communities are not supported. This land cover type generally consists of semipermanent structures, homes, parking lots, pavement or hardscape, and landscaped areas that require maintenance and irrigation (e.g., ornamental greenbelts). Typically, this land cover type is unvegetated or supports a variety of ornamental plants and landscaping.

Urban/developed land occupies the greatest amount of the Project area, encompassing approximately 5,578.52 acres of the Project area. The urban/developed land mainly occurs within the City itself, in the western portion of the Project area (Figure 6).

3.2 Jurisdictional Wetlands and Waters
The Project area supports wetlands and waters potentially subject to the regulatory jurisdiction of the USACE pursuant to Section 404 of the CWA, RWQCB pursuant to Section 401 of the CWA or the Porter-Cologne Water Quality Control Act (Porter-Cologne Act), and the CDFW pursuant to Section 1600 et seq. of the California Fish and Game Code (CFGC). Aquatic and riparian vegetation communities occurring in the Project area may fall under the regulatory jurisdiction of the USACE, RWQCB, or CDFW.

As described in Section 1.3.3, Hydrology, numerous major and minor aquatic features occur across the two watersheds in which the Project area is located (Figure 5). This includes features that are defined by the USACE as traditional navigable waters, are tributaries, or have direct connections to the Pacific Ocean. Most of the rivers, streams, and creeks that occur in the Project area are documented aquatic resources under the jurisdiction of the USACE, RWQCB, and CDFW, pursuant to Sections 404 and 401 of the CWA and Section 1602 of the CFGC, respectively. The wetlands, waters, and riparian vegetation communities documented in the Project area and described in Section 3.1, Vegetation Communities and Land Cover Types, including fresh water, freshwater emergent wetland, non-vegetated channel, and riparian forest/scrub, may also be under federal and state jurisdiction. In addition, wetland waters and non-wetland waters, including non-vegetated stream channels, erosional features, gullies, and concrete-lined channels, that occur in the Project area may fall under the regulatory jurisdiction of the USACE, RWQCB, or CDFW. However, only these agencies can make a final determination of jurisdictional boundaries.

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Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project

3.3 Sensitive Plant and Wildlife Species
Sensitive species are those recognized by federal, state, or local agencies as being potentially vulnerable to impacts because of rarity, local or regional reductions in population numbers, isolation/restricted genetic flow, or other factors. Sensitive plant species include those listed as threatened or endangered, proposed for listing, or candidates for listing by the USFWS and CDFW; those considered sensitive by the CDFW; or those species included in the California Rare Plant Rank (CRPR) inventory, maintained by the CNPS. Sensitive wildlife species include those listed as threatened or endangered, proposed for listing, candidates for listing by the USFWS and CDFW; those considered sensitive by the CDFW; or the CDFW Watch List (WL).

Based on the database search results, which included a 1-mile buffer in addition to the Project area for the California Natural Diversity Database, a two quadrangle search (La Habra and Yorba Linda) for the CNPS inventory and the IPaC query, ten sensitive plant species and 20 sensitive wildlife species have been documented in and have the potential to occur in the Project area (Figure 7, Historical Species with Potential to Occur). These species are listed in Table 2, Sensitive Plant Species Documented in the Project Area, and Table 3, Sensitive Wildlife Species Documented in the Project Area (Calflora 2025; CDFW 2025a; CDFW 2025b; CNPS 2025; USFWS 2025b).

3.3.1 Sensitive Plant Species
A total of ten sensitive plant species (Table 2) have been documented within a 1-mile buffer of the Project area and are discussed in more detail in the following sections.

Table 2. Sensitive Plant Species Documented in the Project Area Scientific Name Common Name Federal/State/CRPR
Astragalus brauntonii Braunton's milk-vetch FE/None/1B.1 Berberis nevinii Nevin's barberry FE/CE/1B.1
Calochortus weedii var. intermedius Intermediate mariposa-lily None/None/1B.2 Dudleya multicaulis Many-stemmed dudleya None/None/1B.2 Eriastrum densifolium ssp. sanctorum Santa Ana River woollystar FE/CE/1B.1 Juglans californica Southern California black walnut None/None/4.2 Lepidium virginicum var. robinsonii Robinson's pepper-grass None/None/4.3 Nasturtium gambelii Gambel's water cress FE/CT/1B.1
Phacelia hubbyi Hubby's phacelia None/None/4.2
Romneya coulteri Coulter's matilija poppy None/None/4.2 Sources: Calflora 2025; CDFW 2025a, 2025b; CNPS 2025; USFWS 2025b.

Notes: CE = California endangered; CRPR = California Rare Plant Rank; CT = California threatened; FE = federally endangered; CRPR: 1B = rare, threatened, or endangered in California and elsewhere; .1 = seriously threatened in California (over 80 percent of occurrences threatened/high degree and immediacy of threat); .2 = moderately threatened in California (20–80 percent occurrences threatened/moderate degree and immediacy of threat)
Braunton's Milk-vetch (Astragalus brauntonii)
• Status: Federally endangered, CRPR 1B.1
Biological Resources Technical Report 14 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project • Distribution: As of 2023, 60 known occurrences are present in Southern California, primarily within Los Angeles, Orange, and Ventura Counties. • Habitat: Coastal scrub and valley and foothill grassland, in recent burns or disturbed areas, usually sandstone with carbonate layers at elevations between 15 and 2100 feet amsl (CNPS 2025).
• Suitable Habitat in Project Area: Coastal scrub and annual grassland. • Occurrence in Project Area: Documented in the eastern portion of the Project area (Figure 7).
• Years Documented: 2013
Nevin’s Barberry-vetch (Berberis nevinii)
• Status: Federally endangered, State Endangered, CRPR 1B.1 • Distribution: Southern California, primarily within Los Angeles, San Bernardino, Riverside, and Ventura Counties.
• Habitat: Chaparral, coastal scrub, cismontane woodland, and riparian scrub at elevations between 230 and 2705 feet amsl (CNPS 2025).
• Suitable Habitat in Project Area: Chaparral, coastal scrub, cismontane woodland, and riparian scrub.
• Occurrence in Project Area: Documented in the western portion of the Project area. • Years Documented: Unknown
Intermediate Mariposa-lily (Calochortus weedii var. intermedius) • Status: CRPR 1B.2
• Distribution: Southern California, primarily in the South Coast and Peninsular Range regions.
• Habitat: Coastal scrub, valley and foothill grassland with rocky, calcareous soils at elevations between 345 and 2,805 feet amsl (CNPS 2025). • Suitable Habitat in Project Area: Coastal scrub and annual grassland with calcareous soil.
• Occurrence in Project Area: Documented in the southeastern and northeastern portions of the Project area (Figure 7).
• Years Documented: 1937, 1998, 2000, 2005, 2008, 2010, 2011, 2017, 2019 •
Many-stemmed Dudleya (Dudleya multicaulis)
• Status: CRPR 1B.2
• Distribution: Southern California, primarily in Orange County. • Habitat: Chaparral, coastal scrub, valley and foothill grassland, often in clay soils, at elevations between 50 and 2,590 feet amsl (CNPS 2025).

Biological Resources Technical Report 15 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project • Suitable Habitat in Project Area: Chaparral, coastal scrub, and annual grassland with clayey soils.
• Occurrence in Project Area: Documented in the northwestern portion of the Project area (Calflora 2025).
• Years Documented: 2020.

Santa Ana River Woollystar (Eriastrum densifolium ssp. sanctorum) • Status: Federally endangered, California endangered, CRPR 1B.1 • Distribution: Santa Ana River drainage in southern California. • Habitat: Chaparral, coastal scrub in gravelly or sandy soils at elevations between 300 and 2,00 feet amsl (CNPS 2025).
• Suitable Habitat in Project Area: Chaparral and coastal scrub with sandy soil. • Occurrence in Project Area: Documented in the northern portion of the Project area (CNPS 2025).
• Years Documented: 1980
Southern California Black Walnut (Juglans californica)
• Status: CRPR 4.2
• Distribution: Central valley and the coast range valleys from northern to southern California.
• Habitat: Chaparral, cismontane woodland, coastal scrub, riparian woodland, in alluvial soils, at alevations between 165 and 2,955 feet amsl (CNPS 2025). • Suitable Habitat in Project Area: Chaparral, coastal scrub, annual grassland, cismontane woodland with alluvial soils.
• Occurrence in Project Area: Documented in the northern, northeastern, and eastern portions of the Project area (Calflora 2025).
• Year Documented: 2014, 2019, 2020, 2021, 2022.

Robinson's Pepper-grass (Lepidium virginicum var. robinsonii) • Status: CRPR 4.3
• Distribution: Southwestern California, between Santa Barbara and San Diego counties. • Habitat: Chaparral, coastal scrub at elevations between 5 and 2,905 feet amsl (CNPS 2025).
• Suitable Habitat in Project Area: Chaparral and coastal scrub. • Occurrence in Project Area: Documented in the northern portion of the Project area (Figure 7).
• Years Documented: 2010
Biological Resources Technical Report 16 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Gambel's Water Cress (Nasturtium gambelii)
• Status: Federally endangered, California threatened, CRPR 1B.1 • Distribution: Very few scattered occurrences in southern California. • Habitat: Brackish and freshwater marshes and swamps at elevations between 15 and 1,085 feet amsl (CNPS 2025).
• Suitable Habitat in Project Area: Freshwater
• Occurrence in Project Area: Documented in the southern portion of the Project area (CNPS 2025).
• Years Documented: 1980 (possibly extirpated).

Hubby's Phacelia (Phacelia hubbyi)
• Status: CRPR 4.2
• Distribution: Southern coastal California, primarily in Santa Barbara, Ventura, Los Angeles, and Orange Counties.

Habitat: Chaparral, coastal scrub, valley and foothill grassland in gravelly, rocky, and talus soils at elevations between 0 and 3,280 feet amsl (CNPS 2025). • Suitable Habitat in Project Area: Chaparral, coastal scrub, and annual grassland with rocky and talus soils.
• Occurrence in Project Area: Documented in the eastern portion of the Project area (Calflora 2025).
• Years Documented: 2023, 2025.

Coulter's Matilija Poppy (Romneya coulteri)
• Status: CRPR 4.2
• Distribution: Coastal and inland southern and central California, [primarily in Orange and San Bernardino Counties.
• Habitat: Chaparral, coastal scrub, often in burned areas, at elevations between 65 and 3,935 feet amsl (CNPS 2025).
• Suitable Habitat in Project Area: Chaparral and coastal scrub. • Occurrence in Project Area: Documented in the eastern portion of the Project area (Calflora 2025).
• Years Documented: 2020.

3.3.2 Sensitive Wildlife Species
A total of 20 sensitive wildlife species (two invertebrate, five reptiles, 11 birds, and two mammals) have been documented in the Project area (Table 3), and are discussed in more detail in the following sections.

Biological Resources Technical Report 17 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Table 3. Sensitive Wildlife Species Documented in the Project Area Species Status
Scientific Name Common Name Federal/State
Invertebrates
Bombus crotchii Crotch’s bumble bee None/CCE
Danaus plexippus Monarch butterfly FPT/None
Reptiles
Actinemys pallida Southwestern pond turtle FPT/SSC
Crotalus ruber Red-diamond rattlesnake None/SSC
Phrynosoma blainvillii Blainville’s (coast) horned lizard None/SSC Salvadora hexalepis virgultea Coast patch-nosed snake None/SSC Spea hammondii Western spadefoot toad FPT/SSC
Birds
Aimophila ruficeps canescens Southern California rufous-crowned sparrow
None/WL
Ammodramus savannarum Grasshopper sparrow None/SSC
Aquila chrysaetos Golden Eagle BGEPA/CFP, WL
Athene cunicularia Western burrowing owl None/CCE, SSC
Campylorhynchus brunneicapillus
sandiegensis Coastal cactus wren BCC/SSC
Empidonax traillii extimus Southwestern willow flycatcher FE/SE Eremophila alpestris actia California horned lark None/WL Icteria virens Yellow-breasted chat None/SSC
Polioptila californica californica Coastal California gnatcatcher FT/SSC Setophaga petechia Yellow warbler None/SSC
Vireo bellii pusillus Least Bell’s vireo FE/CE
Mammals
Eumops perotis californicus Western mastiff bat None/SSC Nyctinomops femorosaccus Pocketed free-tailed bat None/SSC Puma concolor mountain lion -central coast & southern
California None/CT
Sources: CDFW 2025a, 2025b; USFWS 2025b.

Notes: BGEPA = federal bald and golden eagle protection act; CCE = California candidate endangered; CE = California endangered; CFP= California fully protected; CT = California endangered; FE = federally endangered; FT= federally threatened; FPT = federally proposed threatened; BCC = federal bird of conservation concern; SSC = CDFW species of special concern; WL = CDFW watch list.

Invertebrates
Crotch’s Bumble Bee (Bombus crotchii)
• Status: California candidate endangered species
• Distribution: Southwestern California.

Biological Resources Technical Report 18 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project • Habitat: Occurs in open grasslands, shrublands, chaparral, desert margins, creosote scrub, and semi-urban areas. Forages on species with open flowers and short corollas due to their short tongue, most commonly Fabaceae, Apocynaceae, Asteraceae, Lamiaceae, Hydrophyllacae, Asclepiadaceae, and Boraginaceae species. While little is known about hibernacula of this species, it is likely that it overwinters in soft, disturbed soil and nests underground (Xerces Society 2018).
• Suitable Habitat in Project Area: Cismontane woodland, coastal scrub, chaparral, agricultural land, and urban/developed land with underground cavities, flowering nectar and pollen plants, and open areas with loose soils for overwintering. • Occurrence in Project Area: Documented in the southeastern portion of the Project area (Figure 7).
• Years Documented: 1968, 2024.

Monarch Butterfly (Danaus plexippus)
• Status: Federally proposed threatened, CDFW SSC
• Distribution: North America.
• Habitat: Occurs in a variety of habitats where patches of milkweed (Asclepias sp.), the monarch caterpillar host plant, are present. Overwinters in groves of eucalyptus, cypress, and pine along the California coast and high-elevation forests in Mexico. • Suitable Habitat in Project Area: Cismontane woodland, coastal scrub, chaparral, annual grassland, agricultural land, and urban/developed land with flowering nectar plants, and eucalyptus, cypress, or pine groves for overwintering. • Occurrence in Project Area: Unknown.
• Years Documented: Unknown.

Reptiles
Southwestern Pond Turtle (Actinemys pallida)
• Status: Federally proposed threatened, CDFW SSC
• Distribution: Restricted to the central Coast Range south from the middle of Monterey Bay to the species’ southern range boundary in Baja California. • Habitat: Occurs in slow-moving permanent or intermittent streams, ponds, lakes, permanent and ephemeral wetlands, and reservoirs with emergent basking sites. This species spends most of its life in water, but also requires terrestrial habitats for nesting and during winter (USFWS 2025c; USFWS 2025d).
• Suitable Habitat in Project Area: Fresh water streams and ponds with surrounding uplands for nesting.
• Occurrence in Project Area: Documented in the central and eastern portions of the Project area (Figure 7).

Biological Resources Technical Report 19 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project • Year Documented: 1996, 2010, 2011, 2013.

Red-diamond Rattlesnake (Crotalus ruber)
• Status: CDFW SSC
• Distribution: Southern California’s coastal and inland foothills south through most of the Baja California Peninsula.
• Habitat: Occurs in arid desert in rocky areas, chaparral, woodland, and dense vegetation (Thompson et al 2016).
• Suitable Habitat in Project Area: Chaparral, cismontane woodland, and in disturbed areas where dense vegetation is present.
• Occurrence in Project Area: Documented in the eastern and southeastern portions of the Project area (Figure 7).
• Year Documented: 1995.

Blainville’s (Coast) Horned Lizard (Phrynosoma blainvillii) • Status: CDFW SSC
• Distribution: Sierra Nevada foothills from Butte County to Kern County and throughout the Central and Southern California coast.
• Habitat: Occurs in sandy soils in valley-foothill hardwood, conifer and riparian habitats, as well as in pine-cypress, juniper and annual grassland habitats (CDFW 2000). • Suitable Habitat in Project Area: Riparian forest/scrub and annual grassland with sandy soils.
• Occurrence in Project Area: Documented in the northeastern portion of the Project area (Figure 7).
• Year Documented: 1985, 2011.

Coast Patch-nosed Snake (Salvadora hexalepis virgultea) • Status: CDFW SSC
• Distribution: Coastal and inland southern California into northwestern Baja California, Mexico.
• Habitat: Occurs in coastal sage scrub, chaparral, open woodlands, desert-edge habitats, and rocky hillsides and canyons containing loose, sandy soils (Thompson et al 2016). • Suitable Habitat in Project Area: Costal scrub, chaparral, riparian forest/scrub, cismontane woodland, and annual grassland with sandy soils. • Occurrence in Project Area: Documented in the southeastern portion of the Project area (Figure 7).
• Year Documented: 1993
Biological Resources Technical Report 20 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Western Spadefoot Toad (Phrynosoma blainvillii)
• Status: California candidate threatened species, CDFW SSC • Distribution: California
• Habitat: Occurs primarily in grasslands, but occasional populations also occur in valleyfoothill hardwood woodlands. Some populations persist for a few years in orchard or vineyard habitats (Zeiner et al 1988-1990).
• Suitable Habitat in Project Area: Cismontane woodland and annual grassland with water sources for breeding.
• Occurrence in Project Area: Unknown.
• Year Documented: Unknown.

Birds
Southern California Rufous-crowned Sparrow (Aimophila ruficeps canescens) • Status: CDFW WL
• Distribution: Southern California and northwestern Baja California, Mexico. • Habitat: Occurs in coastal sage scrub and sparse mixed chaparral on rocky hillsides and in canyons, and is also found in open sage scrub/grassy areas of successional growth.

Tends to be more common in areas that have burned in the past 15 years (Unitt 2004). • Suitable Habitat in Project Area: Coastal scrub, chaparral, and annual grassland. • Occurrence in Project Area: Documented in the central portion of the Project area (Figure 7).
• Year Documented: 2005, 2008.

Grasshopper Sparrow (Ammodramus savannarum)
• Status: CDFW SSC
• Distribution: United States, Mexico, and Canada, and central America. Only known in California in coastal and central regions.
• Habitat: Restricted to grassland habitats, typically dominated by native bunchgrasses.

Nests are placed hidden within clumps of dense grass, but this species will occupy open areas within prairies, hayfields, and open pastures while foraging for insects (Shuford et al. 2008).
• Suitable Habitat in Project Area: Annual grassland.
• Occurrence in Project Area: Documented in the northern and southeastern portions of the Project area (Figure 7).
• Year Documented: 2001 and 2011.

Biological Resources Technical Report 21 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Golden Eagle (Aquila chrysaetos)
• Status: Federal Bald and Golden Eagle Protection Act, California fully protected,

CDFW WL
• Distribution: Ranges from Alaska and northern Canada south through the western United States and Mexico. Also found across northern Europe, Asia, northern Africa, and parts of the Middle East and Himalayas.
• Habitat: Occurs in mountains up to 12,000 feet amsl, canyon lands, rocky terrain, and riverside cliffs and bluffs. Usually nest on cliffs but may also build nests in trees, on the ground, or in human-made structures and towers (USFWS 2025c). • Suitable Habitat in Project Area: Steep canyons, crags or bluffs within coastal scrub, chaparral, cismontane woodland, and riparian forest/scrub. • Occurrence in Project Area: Documented in the central and southeastern portions of the Project area (Figure 7).
• Year Documented: 2007.

Western Burrowing Owl (Athene cunicularia)
• Status: USFWS Bird of Conservation Concern, CDFW SSC
• Distribution: Throughout the United States, Mexico, Central America, South America, and northeast Caribbean.
• Habitat: Occurs in open, dry annual or perennial grasslands, deserts, and scrublands, as well as agricultural and ruderal landscapes, characterized by low-growing vegetation with available burrows or burrow-like structures such as culverts. Often associated with high densities of burrowing small mammals (Shuford et al. 2008). • Suitable Habitat in Project Area: Annual grassland and coastal scrub with low-growing vegetation and available small mammal burrows or burrow-like structures. • Occurrence in Project Area: Documented in the north-central portion of the Project area (Figure 7).
• Year Documented: 2016.

Coastal Cactus Wren (Campylorhynchus brunneicapillus sandiegensis) • Status: USFWS BCC, CDFW SSC
• Distribution: Northwestern Baja California north through the coastal lowlands in San Diego County and into southern Orange County.
• Habitat: Occurs in coastal cholla and prickly pear (Opuntia littoralis and Opuntia oricola) patches in coastal sage scrub and maritime succulent scrub (Shuford et al. 2008).
• Suitable Habitat in Project Area: Coastal scrub with dense patches of cholla or prickly pear.

Biological Resources Technical Report 22 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project • Occurrence in Project Area: Documented in the central and south-central portions of the Project area (Figure 7).
• Year Documented: 1995, 2005.

Southwestern Willow Flycatcher (Empidonax traillii extimus) • Status: Federally endangered, State endangered
• Distribution: Arizona, California, Colorado, New Mexico, Texas, Utah • Habitat: Occurs in dense riparian vegetation along streams. • Suitable Habitat in Project Area: Non-vegetated channel, riparian forest/scrub • Occurrence in Project Area: unknown.
• Year Documented: unknown.

California Horned Lark (Eremophila alpestris actia)
• Status: CDFW WL
• Distribution: California.
• Habitat: Occurs primarily in grassland and beach habitats but can also be found in disturbed lands, agricultural lands, and alpine fell fields in the Sierra Nevada (CDFW 2025d).
• Suitable Habitat in Project Area: Annual grassland and agricultural land. • Occurrence in Project Area: Documented in the north-central portion of the Project area (Figure 7).
• Year Documented: 2008.

Yellow-breasted Chat (Icteria virens)
• Status: CDFW SSC
• Distribution: United States, southern Canada, Mexico, and central America. • Habitat: Occurs in riparian thickets of willow and other brushy tangles near waterways. • Suitable Habitat in Project Area: Riparian forest/scrub with dense willow coverage. • Occurrence in Project Area: Documented in the northern, central, southern, and southeastern portions of the Project area (Figure 7).
• Year Documented: 2001, 2011, 2013, 2016.

Coastal California Gnatcatcher (Polioptila californica californica) • Status: Federally threatened, CDFW SSC
• Distribution: Southern California to Baja California, Mexico. • Habitat: Occurs almost exclusively in coastal sage scrub vegetation but can also be found in chaparral and riparian habitats (USFWS 2010).
• Suitable Habitat in Project Area: Coastal scrub and chaparral.

Biological Resources Technical Report 23 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project • Occurrence in Project Area: Documented in the northwestern, central, southeastern, and southwestern portions of the Project area (Figure 7).
• Year Documented: Over 400 occurrences documented from 1985 through 2020.

Yellow Warbler (Setophaga petechia)
• Status: CDFW SSC
• Distribution: United States, Canada, Mexico, and central America • Habitat: Occurs primarily in riparian woodlands, and less often in montane chaparral and mixed coniferous forests with thick brush.
• Suitable Habitat in Project Area: Riparian forest/scrub. • Occurrence in Project Area: Documented in the central and northern portions of the Project area (Figure 7).
• Year Documented: 2003, 2011, 2016.

Least Bell’s Vireo (Vireo belli pusillus)
• Status: Federally endangered, California endangered
• Distribution: California and northern Baja California, Mexico during breeding season and winters in southern Baja California, Mexico.
• Habitat: Occurs in a variety of habitats, but most often associated with riparian habitat vegetated with willow species in Southern California below 2,000 feet in elevation.

Requires dense understory shrub cover for nest concealment, with an overstory dominated by willows.
• Suitable Habitat in Project Area: Riparian forest/scrub with dense understory and willow overstory.
• Occurrence in Project Area: Documented in the central, northern, eastern and southeastern portions of the Project area (Figure 7).
• Year Documented: 51 occurrences documented from 1996 to 2018.

Mammals
Western Mastiff Bat (Eumops perotis californicus)
• Status: CDFW SSC
• Distribution: San Joaquin Valley and Coastal Ranges from Monterey County through southern California, from the coast eastward to the Colorado Desert. • Habitat: Occurs in open, semi-arid to arid habitats, including conifer and deciduous woodlands, coastal scrub, annual and perennial grasslands, palm oases, chaparral, desert scrub, and urban habitats. Roosts in rock crevices, cliff faces, high buildings, trees, and tunnels (Zeiner et al 1988-1990).

Biological Resources Technical Report 24 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project • Suitable Habitat in Project Area: Coastal scrub, chaparral, cismontane woodland, annual grassland, and urban/developed land with appropriate tunnels, bridges, and buildings for roosting.
• Occurrence in Project Area: Documented in the south-central portion of the Project area (Figure 7).
• Year Documented: 2007.

Pocketed Free-tailed Bat (Nyctinomops femorosaccus)
• Status: CDFW SSC
• Distribution: Southwestern United States, Mexico, and Central America • Habitat: Occurs in pinyon-juniper woodlands, desert scrub, desert succulent scrub, desert riparian, desert wash, alkali desert scrub, Joshua tree, and palm oasis. Roosts in rock crevices, caverns, or buildings (Zeiner et al 1988-1990). • Suitable Habitat in Project Area: rocky cliffs, cervices, caverns, and urban/developed land with bridges, buildings, tunnels appropriate for roosting. • Occurrence in Project Area: Documented in the central portion of the Project area (Figure 7).
• Year Documented: 1989.

Mountain Lion (Puma concolor)
• Status: California threatened
• Distribution: Western United States, Mexico, Central America and South America. In California, Central Coast and Southern California distinct population segments are state threatened.
• Habitat: Occurs in a variety of habitats including riparian woodland, forest, scrub, chaparral, grassland and desert habitats; wherever mule deer occur. Canyons may serve as long distance movement corridors. Habitat and/or terrain that provides sufficient cover is necessary for hunting, resting and denning.
• Suitable Habitat in Project Area: Riparian forest/scrub, coastal scrub, chaparral, cismontane woodland, annual grassland.
• Occurrence in Project Area: Unknown.

Year Documented: Unknown.

3.3.3 Critical Habitat
Critical habitat is defined as the specific areas within the geographic range occupied by the species at the time of listing that contain the physical or biological features that are essential to the conservation of these endangered or threatened species and that may need special management or protection (USFWS 2025d).

Biological Resources Technical Report 25 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Coastal California gnatcatcher was the only species with designated critical habitat mapped in the Project area and its vicinity (Figure 8, Critical Habitat) (USFWS 2025d). Critical habitat for coastal California Gnatcatcher occurs throughout the northern, central, and southeastern portions of the Project area in areas of open space.

3.3.4 Nesting Birds
The Project area contains suitable nesting habitat for many bird and raptor species protected under the CFGC and the Migratory Bird Treaty Act (MBTA). The majority of habitat for nesting birds in the Project area occurs in the native and ornamental trees, shrubs, and buildings that occur throughout the Project area. The structures in the developed land also have the potential to support nesting by certain species that use structures with eaves, ledges, crevices, cracks, and other “cavities,” nest in or on utility structures, or nest on rooftops, such as black phoebe (Sayornis nigricans), gulls (Larus sp.), and Bewick’s wren (Thryomanes bewickii). Suitable habitat for treeand shrub-nesting species, including sensitive coastal California gnatcatcher, southwestern willow flycatcher, least Bell’s vireo, and yellow warbler, is available in the coastal scrub, chaparral, cismontane woodland, riparian forest/scrub communities in the Project area. The trees throughout the Project area could also support nesting by more common birds, including Anna’s hummingbird (Calypte anna), American crow (Corvus brachyrhynchos), and orioles (Icterus sp.), which often nest in ornamental palm and eucalyptus trees. Grassland- and ground-nesting species, such as the sensitive grasshopper sparrow, California horned lark, and western burrowing owl, all documented in the Project area could nest in the annual grassland and open agricultural land throughout the Project area. The availability of large amounts of high-quality nesting habitat with access to nearby food and water sources make it very likely that birds and raptors use the Project area for nesting.

3.3.5 Sensitive Roosting Bats
The Project area contains suitable foraging and roosting habitat for sensitive bat species, including western Mastiff bat, which was documented south of the Project area (Table 2; Figure 7). The structures in the developed land of the Project area provide suitable roosting habitat for structureand cavity-dwelling bats such as big brown bat (Eptesicus fuscus). Additionally, the numerous native trees in the cismontane woodland and riparian forest/scrub communities and the ornamental trees throughout the developed land of the Project area could provide suitable roosting habitat for treeroosting bats, such as the hoary bat (Lasiurus cinereus) and western red bat (Lasiurus blossevillii), a CDFW species of special concern. There are also numerous non-vegetated channels, wetlands, and freshwater lakes and ponds present in the Project area which provide suitable foraging habitat for bats roosting in the area that forage over sources of open water, such as the western mastiff bat (Eumops perotis). The availability of suitable habitat indicates bats are likely roosting and foraging in the Project area.

Biological Resources Technical Report 26 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project

3.4 Wildlife Corridors and Habitat Linkages
Wildlife corridors provide routes for local movement and also regional linkages and corridors, often following linear topographic, vegetation, or water features. These corridors can be continuous habitats features, or “stepping stone” areas, providing critical rest and foraging areas for birds traveling along migratory routes, for example. Local routes of movement provide constant connections to resources that include sources of water, home/cover sites, and foraging areas. Regional linkages and movement corridors provide larger patches of open space to allow relatively free movement of wildlife species along multiple paths between important resources. These areas allow for not only long-term genetic flow between subpopulations but also critical pathways of seasonal/migratory movements. Larger predatory mammals often use regional corridors for hunting and reproduction needs. Potential wildlife corridors can include streams, riparian areas, and culverts under roadways. Habitat characteristics considered included topography, habitat quality, and adjacent land uses.

The Project area provides opportunities for wildlife movement and dispersal and provides connections to surrounding and nearby open space areas. In addition, the Project area contains suitable nesting, foraging, and nursery sites for many wildlife species.

The major aquatic resources, including rivers and streams, as well as riparian corridors around many of these features, provide important wildlife movement corridors throughout the Project area. These areas function to facilitate amphibian, fish, reptile, bird, and mammal movement in the region.

The Puente-Chino Hills area, located within and surrounding the northern and eastern portions of the Project area, provides connectivity between the Santa Ana mountains to the south and the San Gabriel mountains to the north, and function as a vital corridor for wildlife movement through the open space and native vegetation communities that occur in these areas.

The Project area is also in the Pacific Flyway, the major migratory bird corridor of the western United States. The Project area contains open space, native vegetation, and aquatic resources, and its position in the Pacific Flyway migratory corridor makes it very likely to provide habitat for migratory birds traveling between nesting and wintering areas.

According to the California Essential Habitat Connectivity Project, which maps relatively natural habitat blocks that support native biodiversity, several areas spanning from northeast to southwest in the western portion of the Project area serve as natural landscape blocks (CDFW 2025e).

Additionally, small natural areas are scattered throughout the Project area (Figure 9, Wildlife Corridors/NCCPs).

The Project area is likely to be used as a movement corridor for both sensitive and common wildlife species because of the native vegetation communities, undeveloped open space, inland mountainous regions, and numerous fresh water aquatic resources within and adjacent to the Biological Resources Technical Report 27 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Project area. The open space within the Project area has the potential to provide important habitat connectivity both locally and regionally.

Biological Resources Technical Report 28 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Section 4 Regulatory Framework
This section summarizes federal, state, regional, and local regulations, plans, policies, and programs that provide protection and management of sensitive biological resources that are applicable to the Project. The federal government administers non-marine plant- and wildliferelated issues through the USFWS, while waters of the U.S. issues are administered by the USACE. California law relating to wetland, water-related, and wildlife issues is administered by the CDFW. Under the California Environmental Quality Act (CEQA), impacts associated with a project or program are assessed with regard to significance criteria determined by the CEQA lead agency (in this case, the City) pursuant to the CEQA Guidelines. Biological resources-related laws and regulations that apply include the federal Endangered Species Act, MBTA, Clean Water Act (CWA), CEQA, California Endangered Species Act, and CFGC.

4.1 Federal
Bald and Golden Eagle Protection Act (16 USC 668–668d). This act prohibits the possession, selling, or hunting of bald or golden eagles. This includes living eagles and their feathers, nests, eggs, or body parts.

CWA Section 404 (33 CFR 328.3[a]). These provisions regulate the discharge of dredged or fill material in waters of the U.S, including wetlands. Activities that discharge dredge or fill material into waters of the U.S. can be authorized by the USACE.

On August 29, 2023, the U.S. Environmental Protection Agency and the USACE issued a final rule to amend the final “Revised Definition of Waters of the U.S.” The 2023 final rule became effective on September 8, 2023. Under the 2023 final rule:
(a) Waters of the U.S. are defined as:

1. Waters which are:
i. Currently used, or were used in the past, or may be susceptible to use in interstate or foreign commerce, including all waters which are subject to the ebb and flow of the tide;
ii. The territorial seas; or
iii. Interstate waters;

2. Impoundments of waters otherwise defined as waters of the United States under this definition, other than impoundments of waters identified under (a)(5) of this section;

3. Tributaries of waters identified in (a)(1) or (2) of this section that are relatively permanent, standing or continuously flowing bodies of water;
Biological Resources Technical Report 29 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project

4. Wetlands adjacent to the following waters:
i. Waters identified in (a)(1) of this section; or
ii. Relatively permanent, standing or continuously flowing bodies of water identified in (a)(2) or (a)(3) of this section and with a continuous surface connection to those waters; iii. Intrastate lakes and ponds not identified in (a)(1) through (4) of this section that are relatively permanent, standing or continuously flowing bodies of water with a continuous surface connection to the waters identified in (a)(1) or (a)(3) of this section.

Federal Endangered Species Act, Sections 7 and 9 (16 USC 1531 et seq.; 50 CFR Part 402). This act prohibits the “take” (i.e., harm, harass, or kill individuals or destroy associated habitat) of species federally listed as threatened or endangered. Take incidental to otherwise lawful activities can be authorized by the USFWS through a permit under the federal Endangered Species Act, Sections 4(d), 7, or 10(a).

MBTA (16 USC 703–712; 50 CFR 10). The MBTA prohibits the direct or indirect take of migratory birds and their active nests unless permitted.

4.2 State
Birds of Prey Protection Provision (California Fish and Game Code, Section 3503.5). This provision prohibits the taking of birds of prey (Order Falconiformes and Strigiformes), including their nests and eggs.

California Endangered Species Act (California Fish and Game Code, Section 2050 et seq.). This act prohibits any activities that would jeopardize or take a species designated as threatened or endangered by the state.

Streambed Alteration Agreement (California Fish and Game Code, Section 1600). The CFGC requires any person who proposes a project that will substantially divert or obstruct the natural flow or substantially change the bed, channel, or bank of any river, stream, or lake, or their tributaries, or use materials from a streambed to submit a notification for a Streambed Alteration Agreement to the CDFW.

California Fish and Game Code, Section 1602. Section 1602 regulates water resources in the State of California. Activities that divert or obstruct the natural flow of or change or use material from the bed, channel, or bank of any river, stream, or lake may be authorized by the CDFW. CDFW jurisdiction includes intermittent and perennial watercourses and extends to the top of the bank of a stream or lake if unvegetated or to the limit of the adjacent riparian vegetation, located contiguous to the watercourse, if the stream or lake is vegetated.

Biological Resources Technical Report 30 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project California Fish and Game Code, Section 3503. Section 3503 prohibits the take, possession, or needless destruction of the nests or eggs of any birds except as otherwise provided by the code or any regulation made pursuant thereto.

CEQA, as amended (California Public Resources Code, Section 21000 et seq.). The goal of CEQA is to assist California public agencies in identifying potentially significant negative environmental impacts caused by their actions and avoiding or mitigating those impacts when feasible.

California Fully Protected Wildlife Species Provision (California Fish and Game Code, Sections 3511, 4700, 5050, and 5515). These provisions prohibit the taking of fully protected birds, mammals, amphibians, and fish.

California Native Plant Protection Act of 1977 (California Fish and Game Code, Sections 1900–1913).

These provisions preserve, protect, and enhance endangered or rare native plants of the state.

Regional Water Quality Control Board (RWQCB). The RWQCB regulates impacts to water quality under Section 401 of the CWA. A project must comply with Section 401 of the CWA before the USACE can issue a Section 404 Permit. The RWQCB will issue a Section 401 Water Quality Certification or Waiver of Certification, depending on the extent of impacts to waters of the United States. The RWQCB also regulates impact to waters of the state (usually limited to “isolated” waters or swales that may not fall under USACE jurisdiction) under the Porter-Cologne Act.

Natural Community Conservation Planning Act (NCCP), as amended (California Fish and Game Code, Sections 2800–2835). The primary objective of the Natural Community Conservation Planning Act (NCCP) program is to conserve natural communities at the ecosystem level while accommodating compatible land use. The program seeks to anticipate and prevent the controversies and gridlock caused by species’ listing by focusing on the long-term suitability of wildlife and plant communities and including key interests in the process.

Porter-Cologne Water Quality Control Act. Regulated by the RWQCB for impacts to waters of the state. Although water quality issues related to impacts to waterways are normally addressed in a Section 401 Water Quality Certification, should a water of the State of California be determined by the USACE not to have CWA jurisdiction, the Porter-Cologne Act would be addressed under a Construction General Permit, State General Waste Discharge Order, or Waste Discharge Requirements, depending on the level of impact and the properties of the waterway.

4.3 Local

4.3.1 City of Brea General Plan
The City's comprehensive General Plan was adopted in 2003 (2003 Brea General Plan). The 2003 Brea General Plan identifies the community’s vision for its collective future and establishes the fundamental framework to guide future decision-making about development, resource Biological Resources Technical Report 31 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project management, public safety, public services, and general community well-being. During creation of the General Plan, the community worked together to craft this vision and define it through text and illustrations. The General Plan reflects the planning desires and values of Brea residents, the business community, community educators, and elected and appointed officials.

The 2003 Brea General Plan describes how Breans will work to retain the natural and aesthetic qualities that make their City unique, but at the same time, respond to the dynamics of regional growth and meeting changing community needs. The 2003 Brea General Plan serves as a policy guide, balancing these interrelated factors to Brea’s community vision. The goals and policies contained in the City's General Plan supports the overarching vision statement, which is:
"IMAGINE BREA: Brea will be a community that provides great places to live, work, learn, and play; Places that respect the community's natural and cultural resources; Provide open space and public spaces that appeal to all Breans; Encourage economic vitality, and enhance the overall quality of life for all residents."
In support of this vision statement, the community defined four overarching goals that embody the community’s values and will guide all decisions made pursuant to this General Plan (City of Brea 2003).

Goal 1: Create an inclusive community that strives to meet the needs of residents of all ages, income levels, occupations, family types, and lifestyles.

Goal 2: Plan for the sustainable stewardship of natural resources.

Goal 3: Provide a range of mobility options that reduce dependence on the automobile.

Goal 4: Maintain a sustainable economic base to provide a solid fiscal foundation and diverse employment opportunities, and to ensure the provision of quality community facilities and services.

In support of the City’s commitment to enhance the living environment for all residents by providing, facilitating, and supporting parks, recreation facilities and programs, and open space of high quality in a cost-effective manner, the following community resource (CR) goals were put in place:

Goal CR-1: Provide a variety of parks and recreation facilities that meet the diverse needs and interests of the community.

Goal CR-2: Protect and preserve existing parks and recreation facilities.

Goal CR-3: Maximize use of open space areas capable of supporting park-type activities.

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Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Goal CR-4: Preserve open space aggressively for diverse purposes – as a visual and scenic resource, for habitat conservation, to protect watersheds, and for recreation.

Goal CR-5: Provide a flexible and balanced open space and conservation plan.

Goal CR-6: Provide an extensive trail system that links all areas of Brea.

Goal CR-7: Encourage an urban and walkway trail system within the urban areas of the City.

Goal CR-8: Preserve and maintain wildlife and animal movement corridors.

Goal CR-9: Preserve and maintain open space, natural habitat, and vegetation communities that support wildlife species and animals.

Goal CR-10: Pursue aggressively the preservation and protection of scenic resources.

Goal CR-11: Conserve and protect water resources through water conservation standards, sustainable development practices, and water quality standards.

Goal CR-12: Protect the beneficial uses of ground and surface waters.

Goal CR-13: Improve air quality.

Goal CR-14: Preserve historically significant landmarks and/or sites, individual structures, objects, and neighborhoods, and encourage appropriate rehabilitation.

Goal CR-15: Make all Breans aware of the importance of historic preservation.

4.3.2 Orange County Transportation Authority Natural Community Conservation Plan (NCCP)/Habitat Conservation Plan (HCP) Planning Agreement
The Orange County Transportation Authority (OCTA) NCCP/HCP accommodates the implementation of the OCTA's 13 proposed freeway projects proposed under Measure M (M2), designed to reduce congestion, increase capacity, and improve traffic flow of Orange County's important transportation infrastructure. It would also accommodate management activities conducted on the OCTA acquired lands (or preserves) within Orange County. The M2 NCCP/HCP includes the lands along existing freeways in which M2 freeway improvement projects will be constructed and provides a framework to protect and enhance natural resources in Orange County while streamlining the environmental permitting process for Covered Projects and Activities. Covered projects and activities include 13 freeway improvement projects and ongoing management, restoration, and monitoring activities in preserves associated with the M2 NCCP/HCP. The M2 NCCP/HCP fulfills Biological Resources Technical Report 33 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project the requirements of issuance of take permits from the California Department of Fish and Game (CDFG) and the United States Fish and Wildlife Service (USFWS).

Biological Resources Technical Report 34 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Section 5 Thresholds of Significance
Appendix G of the CEQA Guidelines (CEQA Guidelines, Section 15000 et seq.) defines “significant effect on the environment” as a “substantial, or potentially substantial adverse change in the environment.” Appendix G of the CEQA Guidelines further indicates that there may be a significant effect on biological resources if the project would:

1. Have a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or special status species in local or regional plans, policies, or regulations, or by the California Department of Fish and Game or U.S. Fish and Wildlife Service.

2. Have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies, and regulations or by the California Department of Fish and Game or U.S. Fish and Wildlife Service.

3. Have a substantial adverse effect on state or federally protected wetlands (including, but not limited to marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption, or other means.

4. Interfere substantially with the movement of any native resident or migratory fish or wildlife species or with established native resident or migratory wildlife corridors, or impede the use of native wildlife nursery sites.

5. Conflict with any local policies or ordinances protecting biological resources, such as a tree preservation policy or ordinance.

6. Conflict with the provisions of an adopted Habitat Conservation Plan, Natural Community Conservation Plan, or other approved local, regional, or state habitat conservation plan.

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Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Section 6 Impacts
Impacts to biological resources from implementation of the Project are categorized quantitatively as direct and indirect impacts.

Direct impacts to biological resources occur when significant alterations or destruction occurs during the course of, or because of, Project implementation. Examples of such impacts include removing, disturbing, or grading vegetation; dredging or grading a stream bank; filling wetlands with any materials; erecting any structures, including in a stream; and severing or physically restricting wildlife corridors and the distribution of individual species or resources. Other direct impacts may include loss of foraging or nesting habitat and loss of individual species as a result of habitat clearing.

Indirect impacts may include elevated levels of noise or lighting, change in surface water hydrology within a floodplain, and increased erosion or sedimentation. These types of indirect impacts can affect vegetation communities or their potential use by sensitive species. They can also cause the disruption of normal wildlife functions or activities, impacting individual species.

Within the direct and indirect quantitative impacts categories, impacts are also qualified temporally as permanent and temporary impacts.

Permanent impacts may result in irreversible damage to biological resources, including habitat or removal of species from a particular area.

Temporary impacts are interim changes in the local environment due to construction and would not extend beyond project-associated construction, including revegetation of temporarily disturbed areas adjacent to native habitats.

An analysis of the exact acreage of direct impacts that would occur on biological resources, including sensitive plant and wildlife species, sensitive vegetation communities, jurisdictional aquatic resources, and wildlife corridors and habitat linkages, in the Project area from Project implementation is not provided at the programmatic level. This is because such an analysis would be speculative in nature since focused surveys were not conducted, and future site-specific project designs are not known at this time.

6.1 Threshold 1: Sensitive Plant and Wildlife Species

6.1.1 Guidelines for Determination of Significance
Significant impacts to sensitive plant and wildlife species could result if the Project has a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or special-status species in local or regional plans, policies, or regulations or by the CDFW and USFWS.

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Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project

6.1.2 Impacts Analysis

6.1.2.1 Sensitive Plant Species
Direct Impacts
A total of ten sensitive plant species have been documented by historical literature and databased within one mile of the Project area (refer to Table 2, Sensitive Plant Species Documented in the Project Area, and Figure 7). No biological surveys or focused species surveys were conducted as a part of this Project. The Project area consists of eight habitats and three land cover types (refer to Table 1), including fresh water, freshwater emergent wetland, non-vegetated channel, cismontane woodland, riparian forest/scrub, annual grassland, chaparral, coastal scrub, agricultural land, disturbed land, and urban/developed land. The potential for these habitats and land cover types to provide suitable habitat for sensitive plant species is summarized below.

Developed (Urban/developed Land, Disturbed land, and Agricultural land). Impacts on urban/developed land and agricultural land, which comprises approximately 5,685 acres, have a low potential to impact sensitive plant species because these areas provide little to no suitable habitat value for the sensitive plant species documented in the Project area. However, impacts on disturbed land have the potential to impact sensitive plant species. Impacts to these disturbed habitat could result in potentially significant impacts without mitigation.

Wetlands and Waters (Fresh Water, Freshwater Emergent Wetland, and Non-Vegetated Channel). The aquatic habitats present in the Project area, including fresh water, freshwater emergent wetland, and non-vegetated channel, have the potential to support sensitive plant species, including Gambel’s water cress. Impacts to these vegetation communities could result in potentially significant impacts without mitigation.

Woodland and Forest (Cismontane Woodland and Riparian Forest/Scrub). The cismontane woodland and riparian forest/scrub communities throughout the Project area have the potential to support sensitive plants documented in the Project area, including southern California black walnut and Nevin’s barberry. Impacts to these vegetation communities could result in potentially significant impacts without mitigation.

Upland Vegetation Communities (Annual Grassland, Chaparral, and Coastal Scrub). The upland vegetation communities of annual grassland, chaparral, and coastal scrub present in the Project area provide suitable habitat for many of the sensitive plant species documented as occurring in the Project area, such as Braunton's milk-vetch, intermediate mariposa-lily, manystemmed dudleya, Santa Ana River woollystar, Robinson's pepper-grass, Hubby's Phacelia, Nevin’s barberry Coulter's and Matilija Poppy. Impacts to these vegetation communities could result in potentially significant impacts without mitigation.

Biological Resources Technical Report 38 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Impacts to the vegetation communities listed above as well as disturbed habitat are assumed to be significant without mitigation because they could result in impacts to sensitive plant species. Prior to impacts to undeveloped areas that could support sensitive plant species occurring in the Project area, a site specific biological survey shall be required to be conducted to determine the presence and potential for occurrence of sensitive plant species and to quantify potential impacts on these resources (Mitigation Measure BIO-1). While suitable habitats for the historically documented sensitive plant species may be present in the Project area, many of these species have specific microhabitat requirements, including soils and elevation range restrictions, that may reduce the potential for these species to occur on a particular site. Therefore, site specific biological surveys are needed to analyze potential impacts.

If the results of the biological survey determine that sensitive plant species are not present and do not have a high potential to occur, direct impacts to sensitive plant species would be less than significant, and no further mitigation is required.

Alternatively, if the results of the biological survey determine that sensitive plant species are present or have a high potential to occur due to available suitable habitat, direct impacts to sensitive plant species would occur and further mitigation would be required (Mitigation Measures BIO-2 through BIO-4).

Indirect Impacts
Temporary indirect impacts to sensitive plant species could result during Project implementation, and may include dust, which could disrupt plant vitality in the short term, or construction-related soil erosion and runoff. Permanent edge effects, which are changes that occur at the boundary between two different communities or habitats (i.e., native habitat and urban/developed land), could result during operation of the Project. These edge effects may include intrusions by humans and therefore possible trampling of individual plants, invasion by exotic plant and wildlife species, exposure to urban pollutants (fertilizers, pesticides, herbicides, and other hazardous materials), soil erosion, litter, fire, and hydrologic changes (e.g., surface and groundwater level and quality).

Like the discussion under Sensitive Plant Species, Direct Impacts, if the results of the biological surveys determine that sensitive plant species are not present and do not have a high potential to occur, indirect impacts to sensitive plant species would be less than significant, and no further mitigation would be required.

Alternatively, if the results of the biological survey determine that sensitive plant species are present or have a high potential to occur due to available suitable habitat, indirect impacts to sensitive plant species could occur.

However, the Project would be required to be in compliance with state and local regulations controlling erosion and stormwater runoff, including the National Pollutant Discharge Elimination Biological Resources Technical Report 39 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project System (NPDES) Construction General Permit provisions, which would trigger preparation and compliance with an approved Stormwater Pollution Prevention Plan that would consider the full range of erosion control best management practices (BMPs), including any additional site-specific and seasonal conditions to minimize any water quality and erosion impacts that could result during construction. The City of Brea participates in the NPDES permit program via a partnership consisting of Orange County, all cities within Orange County, and the County Flood Control District. Therefore, through compliance with these regulations, indirect impacts to sensitive plant species would be less than significant, and no mitigation is required.

6.1.2.2 Sensitive Wildlife Species
Direct Impacts
A total of 20 sensitive wildlife species have been documented by historical literature and databased in the Project area (refer to Table 3, Sensitive Wildlife Species Documented in the Project and Figure 7). No biological surveys or focused species surveys were conducted as a part of this Project.

Implementation of the Project on urban/developed land has a low potential to impact sensitive wildlife species because it provides little to no suitable habitat value for the sensitive wildlife species documented in the Project area. However, the ornamental trees and shrubs and structures present in the urban/developed land could provide potential overwintering habitat for monarch butterfly and suitable foraging and roosting habitat for sensitive bats documented in the Project area, including western Mastiff bat. Direct impacts to the trees, shrubs, and structures in the urban/developed land of the Project area could result in direct impacts in the form of foraging, nesting, and roosting habitat loss.

The aquatic habitats present in the Project area including wetlands and streams, have the potential to provide suitable habitat for sensitive reptiles like southwestern pond turtle, and foraging, nesting, for sensitive bird species such as southwestern willow flycatcher, least Bell’s vireo, and yellowbreasted chat.

The woodland and forest communities of cismontane woodland and riparian forest/scrub throughout the Project area support sensitive reptiles, birds, and mammals documented in the Project area, including but not limited to Blainville’s (coast) horned lizard and red-diamond rattlesnake. If sandy and/or gravelly soils are present, these areas may have the potential to support western spadefoot.

The upland vegetation communities of annual grassland, chaparral, and coastal scrub present in the Project area provide suitable habitat for sensitive invertebrates, reptiles, birds, and mammals documented in the Project area. These sensitive wildlife species include monarch butterfly, grasshopper sparrow, coastal cactus wren, western burrowing owl, and California horned lark, Biological Resources Technical Report 40 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project among others. If sandy and/or gravelly soils are present, these areas may have the potential to support western spadefoot.

Although the disturbed and agricultural land throughout the Project area is unlikely to support most of the historically documented sensitive wildlife species, species like western burrowing owl have adapted to frequently use highly cultivated and disturbed areas such as agricultural lands for burrowing (if suitable burrows and soil conditions are available) and as movement corridors.

Impacts to the vegetation communities listed above are assumed to be significant without mitigation because they could result in impacts to sensitive wildlife species. Prior to impacts to sensitive vegetation communities that could support sensitive wildlife species, a biological survey shall be required to be conducted to determine the presence and potential for occurrence of sensitive wildlife species and to quantify potential impacts on these resources (Mitigation Measure BIO-1). .

If the results of the biological survey determine that sensitive wildlife species are not present and do not have high potential to occur, direct impacts to sensitive wildlife species would be less than significant, and no further mitigation is required.

Alternatively, if the results of the biological survey determine that sensitive wildlife species are present or have a high potential due to available suitable habitat, direct impacts to sensitive wildlife species would be considered potentially significant without further mitigation (Mitigation Measures BIO-3, BIO-4, BIO-5, BIO-6).

Nesting Birds
The Project area provides potentially suitable nesting habitat for birds and raptors protected under the CFGC and MBTA. Focused nest surveys were not conducted due to the programmatic nature of the Project. If construction activities or other disruptive Project activities begin during the general bird and raptor nesting season (January 15 through September 15), the Project could result in potentially significant impacts without mitigation. Prior to impacts to potential nesting bird habitat in the Project area, a nesting bird survey would be required to implement regulations protecting sensitive nesting birds, including the CFGC and MBTA (Mitigation Measure BIO-7).

Sensitive Roosting Bats
As previously discussed, suitable roosting habitat for sensitive bat species, including western Mastiff bat, occurs in the structures and trees throughout the Project area. Although no focused nighttime mist-netting or acoustic surveys were conducted, the potential availability of suitable roosting with nearby foraging habitat suggests that bats may be roosting in the Project area.

Therefore, if sensitive roosting bats are present, potential impacts would be considered potentially Biological Resources Technical Report 41 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project significant without mitigation. Prior to impacts to potential roosting bat habitat in the Project area, a roosting bat survey would be required (Mitigation Measure BIO-6).

Critical Habitat
Critical habitat for coastal California gnatcatcher occurs in the Project area (Figure 8). Potential impacts to this sensitive species in its designated critical habitat could occur during implementation of the Project on these opportunity sites and would be considered potentially significant without mitigation. Prior to impacts to coastal California gnatcatcher critical habitat in the Project area, a biological resources survey and habitat assessment would be required to implement regulations protecting critical habitat (Mitigation Measure BIO-1).

Like the discussion under Sensitive Wildlife Species, Direct Impacts, if the results of the biological survey determine that suitable habitat for coastal California gnatcatcher is not present, direct impacts to this sensitive species in its designated critical habitat would be less than significant, and no mitigation is required.

Alternatively, if the results of the biological survey determine that suitable coastal California gnatcatcher habitat is present, direct impacts to designated critical habitat for coastal California gnatcatcher would be considered potentially significant without mitigation. Implementation of Mitigation Measures BIO-3 through BIO-7 would be required to reduce impacts to critical habitat to a less than significant level.

Indirect Impacts
Temporary construction-related and long-term operational indirect impacts to wildlife generally include lighting, increased human activity, hydrologic quality (increased turbidity, excessive sedimentation, flow interruptions, and changes in water temperature), noise, vibration, and trash and garbage, which can attract both introduced terrestrial and native terrestrial and avian predators (such as American crows, common ravens [Corvus corax], coyotes [Canis latrans], domestic dogs [Canis familiaris], raccoons [Procyon lotor], and striped skunks [Mephitis mephitis]). These indirect impacts in the form of habitat disturbance and potential predation could have a significant impact on the sensitive wildlife species historically documented in the Project area, identified in Section 3.3.2, Sensitive Wildlife Species, and discussed under Direct Impacts in Section 6.1.2.2, Sensitive Wildlife Species.

Like the discussion under Sensitive Wildlife Species, Direct Impacts, if the results of the biological survey determine that sensitive wildlife species are not present and do not have a high potential to occur, indirect impacts to sensitive wildlife species would be less than significant, and no mitigation is required.

Biological Resources Technical Report 42 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Alternatively, if the results of the biological survey determine that sensitive wildlife species are present or have a high potential to occur due to available suitable habitat, indirect impacts to sensitive wildlife species could occur.

As previously discussed under Indirect Impacts in Section 6.1.2.1, Sensitive Plant Species, indirect impacts to sensitive wildlife species from hydrologic changes, including erosion, stormwater runoff, and pollution discharges, would be reduced through project compliance with NPDES Construction General Permit provisions.

However, indirect impacts to sensitive wildlife species from lighting, increased human activity, and potential predation by mesocarnivores attracted by trash and garbage could result. Therefore, indirect impacts to sensitive wildlife during Project construction activities would be considered potentially significant without mitigation.

6.1.3 Mitigation Measures
Sensitive Plant Species
Implementation of Mitigation Measure BIO-1 and BIO-2 would reduce potential direct and indirect impacts to sensitive plant species through conducting sensitive plant species focused surveys prior to construction of the Project. Direct impacts to vegetation communities potentially occupied by sensitive plant species would be conserved or restored through the implementation of Mitigation Measure BIO-3 and Mitigation Measure BIO-4.

The operation of future projects proposed as a result of changes to the General Plan under this Project could potentially result in indirect impacts to biological resources, such as edge effects. These potential impacts are not addressed in this report because such impacts would be project specific and variable and to do so at this point would be speculative. Rather these potential indirect impacts resulting from operation of such projects would be addressed on a project-by project basis through the environmental review required under Mitigation Measure BIO-1 and compliance with existing local policies, and federal and state environmental regulations.

Sensitive Plant
MM BIO-1 Pre-project/Activity Biological Resources Survey/Habitat Assessment. Prior to any site disturbance, including grading, vegetation clearing, or fuel modification and prior to the issuance of any construction or clearing, grading, or construction permits for individual development projects that are not exempt from California Environmental Quality Act (CEQA), and in conjunction with any required CEQA review, the future project applicant shall submit one or more documents to the City of Planning Division for review and approval, demonstrating that the project site Biological Resources Technical Report 43 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project does not contain native vegetation, sensitive plants, or undisturbed soils. Examples of acceptable documentation include, but are not limited to, the following:
• Aerial photographs (historic and current) showing grading, building footprints, paving, and landscaped areas over time to support ornamental status, existing landscape plans
• Photographic documentation consisting of georeferenced or dated photographs. • Landscaping plans or as-built drawings demonstrating that vegetation was intentionally planted as part of site development.
• Field survey results prepared by a qualified biologist confirming that existing plant species are ornamental and non-native.

Within the future site-specific project areas exhibiting native vegetation, a sitespecific biological resources survey shall be conducted during the project design phase.

The biological resources survey and habitat assessment shall be conducted by a qualified biologist and shall include but not be limited to the following:
• An analysis of available literature and biological databases, such as the California Natural Diversity Database, to determine sensitive biological resources that have been reported historically from the proposed project vicinity.
• A review of current land use and land ownership within the project vicinity. • An assessment and mapping of vegetation communities present within the project vicinity. If vegetation community mapping has not been conducted on the site in the previous three years, updated vegetation mapping shall be conducted by a qualified biologist as part of the project planning and environmental review process. Vegetation communities shall be mapped according to the Manual of California Vegetation at the alliance level, and a crosswalk table with Holland vegetation communities shall be provided. • A general assessment of the potential for aquatic resources, including wetlands and riparian habitats, to occur on site.
• An evaluation of potential local and regional wildlife movement corridors and an assessment of functions and value retention using online wildlife agency habitat connectivity maps and on-site evaluations.
• A focused habitat assessment to determine if the Project area supports vegetation communities that may provide habitat for plant or wildlife species, to be conducted by a qualified biologist, to determine the potential for sensitive plant or wildlife species to occur in or adjacent to the project area.

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Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project • If the project area supports sensitive vegetation communities, the project proponent shall implement the following weed control methods to minimize the establishment and spread of non-native and invasive weed species in the planning area during construction activities:
− Seeds and plant materials used for revegetation shall be certified weed free. − Straw materials, such as those used for erosion control, shall be certified weed free.

The results of the biological survey shall be presented in a biological technical report.

The survey report shall map and describe the location and extent of observed sensitive resources, including sensitive vegetation communities, regional wildlife movement corridors, plant, and wildlife species within the areas of potential direct and indirect effects for each project area, direct and indirect impacts associated with construction and operation of a project, and the need for further survey, monitoring, or mitigation, including measures pursuant to mitigation measures MM BIO-2, MM BIO-3, MM BIO-4, MM BIO-5, MM BIO-6, and MM BIO-7 of this Program Environmental Impact Report. The biological technical report shall be submitted to and approved by the City of Brea prior to issuance of grading permits. The report shall incorporate applicable mitigation measures (MM BIO-2 through MM BIO-9) to reduce any potentially significant impacts to biological resources.

MM BIO-2: Focused Sensitive Plant Species Surveys. If recommended by the Biological Resources Survey/Habitat Assessment prepared pursuant to Mitigation Measure MM BIO-1, prior to any site disturbance, including grading, vegetation clearing, or fuel modification, focused surveys for future site-specific development shall be conducted, as applicable, in suitable habitat, to determine presence/absence of sensitive plant species on the project site. Focused sensitive plant surveys shall be conducted during the species’ specific blooming periods to determine presence/absence. If sensitive plant species are mapped within any proposed construction, access, or staging areas, these species shall be quantified and flagged, and these areas shall be modified to avoid direct impacts to mapped sensitive plant species. If significant impacts to these species are unavoidable, the impact on these species shall be reduced to a less than significant level through implementation of one or a combination of the following actions, in accordance with a Conceptual Restoration Plan or acquisition of mitigation credits, reviewed and approved by the City of Brea:
• Impacted plants shall be salvaged and relocated to suitable habitat in an on-site restoration area, if possible. If relocation to a restoration area is not practical, Biological Resources Technical Report 45 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project the plants shall be relocated off-site to an appropriate location determined by a qualified biologist.
• Seeds from impacted plants shall be collected for use at a local off-site location, as applicable.
• Off-site habitat that supports the species impacted shall be enhanced or supplemented with seed collected on site.
• Comparable habitat at an approved off-site location shall be determined by a qualified biologist and preserved for relocation, enhancement, or transplant of the impacted sensitive plants.

Mitigation that involves relocation, enhancement, or transplant of sensitive plants shall include all the following:
• Conceptual planting plan prepared by a qualified biologist including grading, planting specifications, and, if appropriate, temporary irrigation. • Planting specifications and fencing and signage to discourage unauthorized access of the planting site.
• Monitoring program prepared by a qualified biologist with clearly stated goals and objectives and well-defined performance standards that result in no net loss of sensitive plant resources. Final success criteria shall be determined based on quality, quantity, and species of plant impacted and in consultation with California Department of Fish and Wildlife and U.S. Fish and Wildlife Service depending on the status of the species. The monitoring program will include measures for adaptive management detailing remedial actions if success criteria are not met in the monitoring time frame. Remedial actions may include, but are not limited to, supplemental water, replanting, and herbivore deterrents/protections.

MM BIO-3 Sensitive Vegetation Communities Impacts Mitigation. If recommended by the Biological Resources Survey/Habitat Assessment prepared pursuant to Mitigation Measure MM BIO-1, prior to any site disturbance, including grading, vegetation clearing, or fuel modification, a biological survey shall be conducted to ground-truth and/or update vegetation communities. Vegetation communities and land cover types will be verified in the field during the required biological survey and will be mapped for impact analysis. Any direct impacts to sensitive vegetation communities require mitigation to comply with California Department of Fish and Wildlife authorizations, as well as the ratios defined in any State or Federal permit(s) issued for the proposed project.

Biological Resources Technical Report 46 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Potential direct permanent impacts to sensitive vegetation communities resulting from project implementation shall be mitigated prior to any vegetation clearing or ground-disturbing activities within the site-specific areas. Mitigation shall be provided at a minimum of 1:1 and to the extent feasible located in the same ecological region or watershed, and functionally equivalent or superior in habitat value.

Mitigation shall be fulfilled through one of the following options:
a. Compensatory mitigation for temporary impacts to sensitive habitats shall be satisfied through the acquisition of mitigation bank credits via a resource agencyapproved mitigation site within the site’s specific watershed or by acquisition of other off-site mitigation credits to be identified and selected in coordination with CDFW. Prior to implementation of project construction impacts (e.g., vegetation clearing or ground-disturbing activities) that would require compensatory mitigation, documentation demonstrating the availability of mitigation credits (i.e., credit ledger) at the approved mitigation site must be submitted to the City of Brea for confirmation; or
b. If credits are not available at a resource agency-approved mitigation site within the site’s specific watershed or through other off-site mitigation credits, implementation of habitat creation, restoration, enhancement, or preservation shall occur through a Habitat Mitigation and Monitoring Plan developed by a qualified biologist. Under this option, a Habitat Mitigation and Monitoring Plan shall be provided and prepared to achieve no net loss of the resource, be timed in relation to project impacts, and comply with Federal and State mitigation requirements.

When proposed mitigation involves habitat enhancement, restoration or creation, the Habitat Mitigation and Monitoring Plan shall include all of the following information:
• Conceptual planting plan including planting zones, grading, and irrigation. • Seed mix/planting palette.
• Planting specifications.
• Monitoring program prepared by a qualified biologist including success criteria that ensure no net loss of sensitive vegetation communities. Final success criteria shall be determined based on quality, quantity, and type of habitat impacted and in consultation with CDFW. The monitoring program shall include measures for adaptive management plan detailing remedial actions if success criteria are not met in the monitoring time frame.

Remedial actions may include, but are not limited to, supplemental water, replanting, and herbivore deterrents/protections.

Biological Resources Technical Report 47 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project For mitigation that involves habitat acquisition, the Habitat Mitigation and Monitoring Plan shall include all the following:
• Location of proposed acquisition.
• Description of the biological resources to be acquired, including support for the conclusion that the acquired habitat mitigates for the specific maintenance impact.
• Documentation that the mitigation area would be adequately preserved and maintained in perpetuity through conservation easements or similar mechanisms.

The identification of mitigation site credits shall be provided to the City of Brea and shall include the following:
• Location of approved mitigation site.
• Description of the mitigation credits to be acquired, including substantial evidence that the acquired habitat mitigates for the specific maintenance impact.
• Documentation of the credits that are associated with a mitigation bank, which has been approved by the appropriate resource agencies. • Documentation in the form of a current mitigation credit ledger.

MM BIO-4: Habitat Restoration for Temporary Impacts. If recommended by the Biological Resources Survey/Habitat Assessment prepared pursuant to Mitigation Measure MM BIO-1, temporary impact areas shall be restored to pre-construction topographic contours and conditions, including the revegetation of native plant communities, where appropriate, following disturbance and prior to Project completion. Habitat restoration and erosion control treatments shall be installed within these short-term impact areas. A Revegetation Plan shall be prepared and shall include site preparation specifications, a plant palette, installation procedures, development of reasonable success criteria, appropriate monitoring and reporting protocols, implementation timelines, and contingency measures and adaptive management in the event of restoration failure. The Revegetation Plan shall be submitted to and approved by the City of Brea. Habitat revegetation shall feature native species that are typical of the area, and associated erosion control best management practices shall include silt fence and microplastic- and weed-free straw fiber rolls, where appropriate. The revegetation areas shall be monitored and maintained by a qualified biologist or restoration specialist for 25 months to ensure adequate establishment and sustainability of the plantings/seedings.

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Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Where a project activity involves potential disturbance of non-native invasive plant species (as identified by the California Invasive Plant Council), these plants shall be entirely removed immediately, where feasible, and the removal shall be monitored by the qualified monitoring biologist to ensure that dispersal of propagules (e.g., seeds and stems) are avoided or minimized. Where removal of plant roots is not feasible (e.g., where erosive flows are predicted), aboveground plant material shall be fully removed and monitored by the qualified monitoring biologist. Where aboveground plant material cannot be removed (e.g., due to limited access), herbicides shall be applied by a licensed pest control advisor, using chemicals permitted as safe within aquatic environments.

Sensitive Wildlife Species
In the event that sensitive wildlife species are identified as present or with a high potential to occur in suitable habitat or other sensitive wildlife species are identified within the potential impact area, impacts would be considered potentially significant without mitigation.

Direct impacts to vegetation communities potentially occupied or used by sensitive wildlife species would be conserved or restored through the implementation of Mitigation Measure BIO-3 and Mitigation Measure BIO-4, listed previously under Sensitive Plant Species Mitigation Measures.

Implementation of Mitigation Measure BIO-5 would reduce potential direct and indirect impacts to sensitive wildlife species, including sensitive roosting bats, through monitoring by a qualified biologist prior to and during construction of the Project. Mitigation Measure BIO-6 and Mitigation Measure BIO-7 would reduce potential direct impacts to sensitive wildlife species, including sensitive birds and raptors, roosting bats, and designated critical habitat for coastal California gnatcatcher, through conducting sensitive bird and wildlife species focused surveys prior to construction.

MM BIO-5: Qualified Monitoring Biologist. If recommended by the Biological Resources Survey/Habitat Assessment prepared pursuant to Mitigation Measure MM BIO-1, a qualified monitoring biologist shall be retained to implement required monitoring.

The qualified monitoring biologist shall be responsible for the following monitoring and reporting tasks.
a. Biological Construction Mitigation/Monitoring Exhibit. Prior to site disturbance, including grading, vegetation clearing, or fuel modification, within the future site-specific project areas that have potential to contain sensitive biological resources, the qualified monitoring biologist shall submit a Biological Construction Mitigation/Monitoring Exhibit, which includes limits of work, proposed monitoring schedule, bird, focused sensitive species, or other wildlife surveys/survey schedules (including general bird nesting and U.S. Fish and Wildlife Service protocol), timing of surveys, bird construction avoidance Biological Resources Technical Report 49 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project areas/noise buffers/barriers, other impact avoidance areas, and any subsequent requirements determined by the qualified monitoring biologist. The Biological Construction Mitigation/Monitoring Exhibit shall include the construction site plan, written and graphic depiction of the proposed project’s biological mitigation/monitoring program, and a schedule for construction activities. Where the potential for impacts to biological resources is limited (e.g., construction within a footprint that consists entirely of previously developed or disturbed lands), the Biological Construction Mitigation/Monitoring Exhibit may be limited to a pre- and post-maintenance verification inspection by a qualified biologist. For highly sensitive resource areas with documented sensitive biological and aquatic resources present, full-time biological monitors may be required, as determined by a qualified biologist. The Biological Construction Mitigation/Monitoring Exhibit shall be approved by the City of Brea prior to the start of construction.
b. Resource Marking/Protection. Prior to site disturbance within the future sitespecific project area, the qualified monitoring biologist shall supervise the placement of orange construction fencing or similar visible marker, staking, or flagging along the limits of the construction area adjacent to sensitive biological habitats, as shown on the Biological Construction Mitigation/Monitoring Exhibit to ensure crews remain within the approved construction limits. These demarcations shall not be required for areas with existing barriers, such as chain-link fencing, along the limits or facilities that are within or adjacent to developed and non-sensitive habitat areas. This task shall include flagging plant specimens and delineating buffers to protect sensitive biological resources (e.g., habitats, sensitive plant and wildlife species, including nesting birds) prior to construction.
c. Cover Trenches. The qualified monitoring biologist shall oversee the construction site so that cover and escape routes for wildlife from excavated areas shall be provided daily. All trenches, holes, and excavations during construction shall be covered at night as directed by the monitoring biologist with plywood, metal plates, or other means, and if plastic sheeting is used, the edges must be covered with soils such that small wildlife cannot access the excavated hole. Soil piles shall be covered at night to prevent wildlife from burrowing in. The edges of the sheeting shall be weighed down by sandbags.

These areas may also be fenced to prevent wildlife from gaining access.

Exposed trenches, holes, and excavations shall be inspected twice daily (i.e., each morning and before sealing the exposed area) by the qualified monitoring biologist to monitor for wildlife entrapment. Excavations shall provide an Biological Resources Technical Report 50 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project earthen ramp to allow for a wildlife escape route. The qualified monitoring biologist shall verify that the contractor has covered all steep-walled trenches or excavations prior to the end of construction daily. If wildlife species are encountered within any trenches or excavated areas, the qualified monitoring biologist shall remove them, if possible, or provide them with a means of escape (e.g., a ramp or sloped surface at no greater than a 30-degree angle) and allow the species to disperse. In addition, the qualified monitoring biologist shall provide training to construction personnel to increase awareness of the possible presence of wildlife beneath vehicles and equipment and to use best judgment to avoid killing or injuring wildlife (refer to Mitigation Measure BIO-5e). d. Structure and Tree Clearance. Prior to the issuance of any permit to allow for the removal or demolition of trees and existing structures within the survey area (particularly any ornamental trees and existing buildings in the developed land areas), the qualified monitoring biologist shall conduct clearance surveys to flush out any wildlife species nesting, roosting, or otherwise occupying the trees or structures. If wildlife species are encountered within any of the trees or structures (outside the general bird nesting season), the qualified monitoring biologist shall remove them, if possible, or provide them with a means of escape and allow the species to disperse. If tree-roosting bats are suspected, slow removal by gently pushing the tree over with heavy equipment is required. e. Pre-Construction Meeting/Education. Prior to site disturbance where the site plan for the construction area indicates that significant impacts to biological resources may occur, as determined by a qualified biologist, a pre-construction meeting shall be held on site with the following in attendance: City of Brea representatives (project planner and building inspector), the construction contractor (if applicable), and the qualified monitoring biologist. At this meeting, the qualified monitoring biologist shall identify and discuss the construction protocols that apply to the proposed activities and the sensitive nature of the adjacent habitat with appropriate project personnel.

At the pre-construction meeting, the qualified monitoring biologist shall submit to the City of Brea representatives and construction contractor a copy of the Biological Construction Mitigation/Monitoring Exhibit that identifies areas to be protected, fenced, and monitored. This data shall include all buffer limits, if applicable.

Prior to the start of construction activities, the qualified monitoring biologist shall meet with the construction contractor and crew and conduct an on-site educational session regarding the need to avoid impacts outside the approved construction Biological Resources Technical Report 51 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project footprint and to protect sensitive plants and wildlife that may occur at the specific facility. This may include but not be limited to explanations of the bird and wetland buffers, the flag system for removal of invasive species or retention of sensitive plants, and clarification of acceptable access routes/methods and staging areas. f. Biological Monitoring and Reporting. The qualified monitoring biologist with stop work authority shall inspect/monitor the project construction area in accordance with the approved Biological Construction Mitigation/Monitoring Exhibit. This may be limited to pre- and post-maintenance inspections, weekly visits, or full-time monitoring, as determined by the qualified monitoring biologist and the City of Brea.

The qualified monitoring biologist shall document monitoring events via a Consultant Site Visit Record. This record shall be sent to the City of Brea project manager each month. However, if weekly reports are submitted as part of a separate agency permit requirement, these reports may be forwarded to the City of Brea in place of Consultant Site Visit Record submittals.

If no deviations from the construction site plan occur during maintenance, no additional documentation is required. However, if deviations from the site plan do occur, such as unanticipated impacts to sensitive vegetation communities or unanticipated discharge of pollutants, a final monitoring report shall be prepared within three months following the completion of mitigation monitoring detailing maintenance and monitoring that occurred, and any remedial or compensatory measures taken.

BIO-6: Focused Sensitive Wildlife Species Surveys. If recommended by the Biological Resources Survey/Habitat Assessment prepared pursuant to Mitigation Measure MM BIO-1, prior to any site disturbance, including grading, vegetation clearing, or fuel modification, focused surveys for future site-specific development shall be conducted, as applicable, in suitable habitat, to determine presence/absence of sensitive wildlife species within the proposed survey area. If sensitive wildlife species or their habitat are present or potentially present based on biological surveys, the following measures shall be implemented.
a. Crotch’s bumble bee. Habitat assessment surveys for California Endangered Species Act (CESA) candidate bumble bee species, with a focus on Crotch’s bumble bee, followed the California Department of Fish and Wildlife (CDFW) methodology from the Survey Considerations for CESA Candidate Bumble Bee Species dated June 6, 2023 (CDFW Survey Considerations) (CDFW 2023). If no Crotch’s bumble bees are found during the focused surveys, but the habitat assessment identified suitable nesting, foraging, or overwintering habitat on the Biological Resources Technical Report 52 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project project site, recommendations outlined in the CDFW Survey Considerations will be followed, including recommendations that a biological monitor be on site during vegetation or ground-disturbing activities that take place during any of the Queen and Gyne Flight Period and Colony Active Period. If Crotch’s bumble bees are observed, project proponents may propose site-specific measures to avoid take, or consult with CDFW to obtain an incidental take permit if take of CESA-protected bumble bees may occur during project activities.
b. Western spadefoot and Monarch butterfly. If western spadefoot or monarch butterfly become listed prior to implementation of future site-specific development projects, focused surveys and consultation with the U.S. Fish and Wildlife Service (USFWS) would be necessary.
c. Western burrowing owl. If suitable habitat for western burrowing owl is present (annual grassland and agricultural land), a qualified biologist shall conduct focused surveys of the site and a 500-foot buffer, as access allows. If no burrowing owls are identified, no further measures are necessary. If burrowing owls are detected, active burrows shall be avoided using buffers outlined in the Staff Report on Burrowing Owl Mitigation, dated March 7, 2012, issued by CDFW. If avoidance is not possible, the qualified biologist shall consult with CDFW. No direct disturbance to burrowing owls or their occupied habitat shall occur without appropriate authorization from CDFW.
d. Least Bell’s vireo. If suitable habitat for least Bell’s vireo is present and clearing, grubbing, grading, or other construction activities may occur between March 15 and September 15, the breeding season of the least Bell’s vireo, a qualified biologist shall conduct focused surveys for the presence of the least Bell’s vireo of the site and areas of potentially suitable habitat within 300 feet or that would be subject to construction noise levels exceeding 60 A-weighted decibels or to the ambient noise level if it already exceeds 60 A-weighted decibel hourly average. If present, measures to minimize noise impacts (such as temporary noise walls/berms) may be required. Noise levels from construction activities during the avian breeding season should not exceed 60 decibels (dBA Leq; or the ambient noise level if they already exceed 60 dBA Leq) at the edge of the occupied habitat. If complete avoidance is not feasible, the qualified biologist shall consult with USFWS. No direct harm to the species shall be allowed without appropriate authorization from USFWS.
e. Southwestern willow flycatcher. If suitable habitat for southwestern willow flycatcher is present and clearing, grubbing, grading, or other construction activities may occur between April 15 through September 15, the breeding season of the southwestern willow flycatcher, a qualified biologist shall conduct Biological Resources Technical Report 53 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project focused surveys for the presence of the southwestern willow flycatcher of the site and areas of potentially suitable habitat within 500 feet. If the species is determined to be present, consultation per Endangered Species Act with USFWS would be necessary and no activities would occur until authorized by USFWS. No direct harm to the species shall be allowed without appropriate authorization from USFWS.
f. Sensitive Bat Species. If suitable roosting habitat (e.g., riparian habitat, snags, wooden buildings, bridges, etc.) for sensitive bat species is present, a qualified biologist shall conduct subsequent focused surveys no less than 14 days prior to removal or disturbance of vegetation or buildings. The survey shall consist of visual and/or acoustic methods as deemed appropriate by the qualified biologist. If no bats are detected, no further measures are necessary. If bat species are detected during surveys, a site-specific plan shall be developed by the qualified biologist. The plan may include, as determined by the qualified biologist, delaying removal of roost habitat until after the maternity roosting period and exclusion of bats from roosting habitat prior to removal of habitat.

The qualified biologist shall consult with CDFW prior to implementing any exclusion activities.
g. Southwestern Pond Turtle. If suitable habitat for southwestern pond turtle is present pursuant to Mitigation Measure MM BIO-1, site-specific measures shall be implemented to avoid impacts, as developed in consultation with a qualified biologist. Measures shall focus on avoiding habitat destruction, protecting individuals during construction, and managing habitat to increase survival though preconstruction surveys, exclusion fencing, biological monitoring, and habitat restoration. Depending on the measures selected, plan approval and conference with the U.S. Fish and Wildlife Service may be required if the action is likely to jeopardize the species’ existence during construction activities. h. Mountain Lion. If suitable habitat for mountain lion is present pursuant to Mitigation Measure MM BIO-1, site-specific measures shall be implemented to minimize habitat loss and fragmentation to improve habitat connectivity and avoid take. These measures shall be developed in consultation with a qualified biologist and may include measures described in the City of Brea General Plan Community Resources Element Policy CR-3e. If presence is established, Resource Agency consultation shall be required to obtain an incidental take permit.
i. Other Sensitive Species. Prior to any demolition work, construction or grading activities within the future site-specific project areas, pre-construction surveys for other sensitive wildlife species, such as reptiles, may be required to Biological Resources Technical Report 54 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project determine presence/absence of sensitive wildlife species within the proposed survey area.

BIO-7: Focused Nesting Bird Surveys. Project activities that may directly (e.g., vegetation removal, clearing and grubbing, building demolition) or indirectly affect (noise, light, or ground vibration) nesting raptors and other protected bird species shall be timed to avoid the nesting season (January 15 through September 15). If Project activities occur within the nesting season, the qualified monitoring biologist shall conduct focused surveys for birds in suitable habitat to determine presence/absence. Surveys shall occur within seven (7) days prior to any construction or grading activities within the future site-specific project areas. Focused sensitive bird surveys shall be conducted during the species’ specific nesting seasons to determine presence/absence within the development footprint plus a buffer, if recommended by the qualified monitoring biologist (refer to mitigation measure MM BIO-5). The survey report shall map and describe the location and extent of observed sensitive bird species that would be impacted within the areas of potential effect for each Project area. If no nesting birds are documented within the individual activity area, construction shall be allowed to proceed. If nesting birds cannot be completely avoided, a no-disturbance buffer shall be established around the active nest, the size of which will be determined by the qualified monitoring biologist based on species of bird and specific construction activities to take place. The size of the buffer can be reduced in consultation with California Department of Fish and Wildlife. Any work within the buffer shall be avoided until the nest is inactive, as determined by the qualified monitoring biologist.

6.1.4 Significance After Mitigation
Implementation of Mitigation Measures BIO-1 through BIO-7 would mitigate direct and indirect impacts to sensitive plant and wildlife species to below a level of significance.

6.2 Threshold 2: Riparian Habitat or Other Sensitive Natural Community

6.2.1 Guidelines for Determination of Significance
A significant impact would result if the Project would have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies, or regulations or by the CDFW or USFWS.

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6.2.2 Impact Analysis
Direct Impacts
A total of eight sensitive vegetation communities and three land cover types occur in the Project area, including fresh water, freshwater emergent wetland, non-vegetated channel, cismontane woodland, riparian forest/scrub, annual grassland, chaparral, coastal scrub, agricultural land, disturbed land, and urban/developed land. Construction activities in areas that contain sensitive vegetation communities could result in potential impacts to these sensitive vegetation communities.

Prior to impacts undeveloped areas occurring in the Project area, a biological survey shall be required to be conducted to determine the presence of sensitive vegetation communities and to quantify potential impacts on these resources (Mitigation Measure BIO-1).

If the results of the biological survey determine that sensitive vegetation communities are not present, direct impacts to sensitive vegetation communities would be less than significant, and no mitigation is required.

Alternatively, if the results of the biological survey determine that sensitive vegetation communities do occur, direct impacts to sensitive vegetation communities would occur and further mitigation would be required (Mitigation Measures BIO-3 through BIO-5.

Impacts to the non-sensitive land cover types, agricultural land, disturbed land, and urban/developed land would not be considered significant or require habitat-based mitigation.

Indirect Impacts
Most of the indirect impacts to sensitive plant species described in Section 6.1, Threshold 1:

Sensitive Plant and Wildlife Species, also result in potentially significant indirect impacts to sensitive vegetation communities. Like the discussion under Indirect Impacts in Section 6.1.2.1, if the results of the biological survey required by the City determine that sensitive vegetation communities do not occur, indirect impacts to sensitive vegetation communities would be less than significant, and no mitigation is required.

Alternatively, if the results of the biological survey determine that sensitive vegetation communities are present, indirect impacts to sensitive vegetation communities could occur.

As previously discussed under Indirect Impacts in Section 6.1.2.1, indirect impacts to sensitive vegetation communities from hydrologic changes, including erosion, stormwater runoff, and pollution discharges would be reduced through project compliance with NPDES Construction General Permit provisions (including preparation and implementation of a Stormwater Pollution Prevention Plan and BMPs). Therefore, through compliance with state and local regulations, Biological Resources Technical Report 56 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project ordinances, and plans, indirect impacts to sensitive vegetation communities would be less than significant, and no mitigation is required.

6.2.3 Mitigation Measures
In the event that sensitive vegetation communities are identified, development of the Project area could result in potentially significant direct impacts to sensitive vegetation communities, including fresh water, freshwater emergent wetland, non-vegetated channel, cismontane woodland, annual grassland, chaparral, and coastal scrub. Implementation of Mitigation Measures BIO-3 through BIO-5 (described under Sensitive Plant and Wildlife Species Direct Impacts Mitigation) would reduce direct impacts to sensitive vegetation communities through monitoring by a qualified biologist, providing mitigation ratios for acreage impacts, creating new vegetation communities and restoring impacted ones.

6.2.4 Significance After Mitigation
Implementation of Mitigation Measures BIO-3 through BIO-5 would reduce potential direct impacts to sensitive vegetation communities to below a level of significance.

6.3 Threshold 3: Jurisdictional Aquatic Resources

6.3.1 Guidelines for Determination of Significance
A significant impact would result if the Project would have a substantial adverse effect on state or federally protected wetlands through direct removal, filling, hydrological interruption, or other means of disturbance.

6.3.2 Impact Analysis
Direct Impacts
Aquatic vegetation communities, including fresh water, freshwater emergent wetland, and nonvegetated channel, occur in the Project area and may fall under the regulatory jurisdiction of the USACE, RWQCB, or CDFW.

Impacts to jurisdictional aquatic resources are assumed to be significant without mitigation. If potentially jurisdictional aquatic resources are identified during the pre-project/activity biological resources survey conducted pursuant to Mitigation Measures BIO-1, a qualified biologist shall conduct a formal aquatic resources delineation (Mitigation Measure BIO-8).. .

If the results of the aquatics resources delineation determine that jurisdictional aquatic resources are not present, direct impacts to jurisdictional aquatic resources would be less than significant, and no further mitigation is required.

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Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Alternatively, if the results of the aquatics resources delineation determine that jurisdictional aquatic resources occur in the site-specific project area, direct impacts to jurisdictional aquatic resources would be potentially significant without further mitigation (Mitigation Measure BIO-9).

Indirect Impacts
Most of the indirect impacts to sensitive plant species and sensitive vegetation communities described in Sections 6.1 and 6.2 also result in potentially significant indirect impacts to jurisdictional aquatic resources. Like the discussion in these sections, if the results of the biological survey determine that impacts to jurisdictional aquatic resources will not occur, indirect impacts to jurisdictional aquatic resources would be less than significant, and no further mitigation is required.

Alternatively, if the results of the biological survey determine that jurisdictional aquatic resources are present, indirect impacts to jurisdictional aquatic resources could occur.

As previously discussed under Indirect Impacts in Section 6.1.2.1, indirect impacts to jurisdictional aquatic resources from hydrologic changes, including erosion, stormwater runoff, and pollution discharges, would be reduced through project compliance with NPDES Construction General Permit provisions (including preparation and implementation of a Stormwater Pollution Prevention Plan and BMPs). Therefore, through compliance with state and local regulations, ordinances, and plans, indirect impacts to jurisdictional aquatic resources would be less than significant, and no mitigation is required.

6.3.3 Mitigation Measures
If jurisdictional aquatic resources are identified, development of the Project area could result in potentially significant direct impacts to jurisdictional aquatic resources. Implementation of Mitigation Measures BIO-3 through BIO-5 (described under Sensitive Plant and Wildlife Species Direct Impacts Mitigation) would reduce direct impacts to jurisdictional aquatic resources through monitoring by a qualified biologist, providing mitigation ratios for acreage impacts, and restoring temporary impact areas.

Prior to construction of the Project and implementation of Mitigation Measures BIO-3 through BIO-5, a formal aquatic resources delineation and resource agency (USACE, CDFW, and RWQCB) approval of the mitigation strategy to compensate for impacts to jurisdictional aquatic resources through the permitting process shall be required. Implementation of Mitigation Measure BIO-8 and Mitigation Measure BIO-9 would further reduce direct impacts to jurisdictional aquatic resources through conducting an aquatic resources delineation and obtaining resource agency permits.

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Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project BIO-8 Aquatic Resources Delineation. If potentially jurisdictional aquatic resources are identified during pre-project/activity surveys pursuant to Mitigation Measure MM BIO-1, a qualified biologist shall conduct a formal aquatic resources delineation following the methods outlined in the 1987 U.S. Army Corps of Engineers Wetland Delineation Manual and applicable Regional Supplement to the U.S. Army Corps of Engineers Wetland Delineation Manual to map the extent of wetlands and non-wetland waters, determine jurisdiction, and assess potential impacts. The results of the delineation shall be presented in an aquatic resources delineation report. The aquatic resources delineation report shall be used in consultation with the U.S. Army Corps of Engineers, Regional Water Quality Control Board, and California Department of Fish and Wildlife for necessary authorization or permit, as described in Mitigation Measure MM BIO-9.

BIO-9 Potentially Jurisdictional Aquatic Resources Permitting. Temporary and permanent impacts to the wetland and non-wetland waters potentially under the jurisdiction of the U.S. Army Corps of Engineers, Regional Water Quality Control Board, and California Department of Fish and Wildlife, shall be authorized by the U.S. Army Corps of Engineers, Regional Water Quality Control Board, and California Department of Fish and Wildlife, as applicable. Approved temporary and permanent impacts to the potentially Federal and State jurisdictional aquatic resources in the project area require compensatory mitigation through proposed on- or off-site habitat restoration, creation, or enhancement to the satisfaction of the U.S. Army Corps of Engineers, Regional Water Quality Control Board, and California Department of Fish and Wildlife to achieve a no-net loss of Federal and State jurisdictional wetland and non-wetland waters.

6.3.4 Significance After Mitigation
Implementation of Mitigation Measures BIO-3 through BIO-5, Mitigation Measure BIO-8, and Mitigation Measure BIO-9 would reduce potential direct impacts to jurisdictional aquatic resources to below a level of significance.

6.4 Threshold 4: Wildlife Corridors and Habitat Linkages

6.4.1 Guidelines for Determination of Significance
A significant impact would occur if the Project would interfere substantially with the movement of any native resident or migratory fish or wildlife species, with established native resident or migratory wildlife corridors, or impede the use of native wildlife nursery sites.

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6.4.2 Impact Analysis
Direct Impacts
As discussed in Section 3.4, Wildlife Corridors and Habitat Linkages, the Project area is likely to be used as a wildlife movement corridor because it provides suitable nesting, foraging, nursery, and dispersal areas for both sensitive and common wildlife species due to the presence of native vegetation communities and its connection and proximity to Puente-Chino Hills area, the Pacific Coast, as well the Santa Ana mountains to the south and the San Gabriel mountains to the north.

There are numerous aquatic resources in and surrounding the Project area, which function as largescale wildlife movement corridors for resident and migratory birds, large mammals, and aquatic species both locally and regionally. The cismontane woodland and riparian forest/scrub communities in the Project area in particular, are high-quality, contiguous sections of these habitats that support movement and linkages to other habitats along the Pacific Coast and through the mountains to the east for both local and migratory species. The residential and commercial development throughout much of the Project area has the potential to limit wildlife movement through the Project area.

Impacts to the wildlife corridors and habitat linkages are assumed to be significant without mitigation. Prior to impacts to potential wildlife corridors and habitat linkages, a biological survey shall be required to be conducted to determine the presence and potential for occurrence of these resources (Mitigation Measure BIO-1). Thus, prior to individual project construction in areas that contain sensitive vegetation communities or those that could support wildlife corridors and habitat connectivity (such as agricultural land), a biological survey would be conducted to determine if the area is used as a wildlife corridor or linkage to other sensitive habitats.

If the results of the biological survey determine that wildlife corridors or habitat linkages are not present, direct impacts would be less than significant, and no further mitigation is required.

Alternatively, if the results of the biological survey determine that wildlife corridors and habitat linkages are present, direct impacts would be considered potentially significant without further mitigation (Mitigation Measures BIO-3 through BIO-6.

Indirect Impacts
Wildlife movement corridors and habitat connectivity would be impacted by many of the other indirect effects discussed in Section 6.1.2.2 for indirect impacts to sensitive wildlife species. Like the discussion under Sensitive Wildlife Species, Direct Impacts, if the results of the biological survey determine that wildlife corridors and habitat linkages are not present, indirect impacts to wildlife corridors and habitat linkages would be less than significant, and no mitigation is required.

Biological Resources Technical Report 60 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Alternatively, if the results of the biological survey determine that wildlife corridors and habitat linkages are present, indirect impacts to sensitive wildlife species could occur.

As previously discussed in Section 6.1.2.2, indirect impacts to wildlife corridors and habitat linkages from hydrologic changes, including erosion, stormwater runoff, and pollution discharges, would be reduced through project compliance with NPDES Construction General Permit provisions.

However, indirect impacts to wildlife corridors and habitat linkages from lighting and increased human activity could result. Therefore, indirect impacts to wildlife corridors and habitat linkages would be considered potentially significant without mitigation.

6.4.3 Mitigation Measures
If wildlife corridors and habitat linkages are identified, during pre-project/activity biological resources survey pursuant to Mitigation Measures BIO-1, development of the Project area could result in potentially significant direct and indirect impacts to wildlife corridors and habitat linkages in the Project area. Implementation of Mitigation Measures BIO-3 through BIO-6 (described under Sensitive Plant and Wildlife Species Direct Impacts Mitigation) would reduce direct and indirect impacts to wildlife corridors and habitat linkages through monitoring by a qualified biologist, providing mitigation ratios for acreage impacts, creating new vegetation communities and restoring impacted ones, and conducting sensitive bird and wildlife species focused surveys prior to construction.

6.4.4 Significance After Mitigation
Potential direct and indirect impacts to wildlife corridors and habitat linkages would be less than significant with implementation of Mitigation Measures BIO-3 through BIO-6.

6.5 Threshold 5: Local Policies and Ordinances

6.5.1 Guidelines for Determination of Significance
A significant impact would result if the Project would conflict with any local policies or ordinances protecting biological resources, such as a tree preservation policy or ordinance.

6.5.2 Impact Analysis
As discussed in Sections 6.1 through 6.4, the Project’s potential impacts to sensitive plant and wildlife species, sensitive vegetation communities, jurisdictional aquatic resources, and wildlife corridors and habitat linkages would be potentially significant before incorporation of mitigation.

However, implementation of mitigation measures that fully mitigate impacts to sensitive plant and wildlife species, sensitive vegetation communities, jurisdictional aquatic resources, and wildlife corridors and habitat linkages discussed in those sections, would fully mitigate for potential Biological Resources Technical Report 61 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project impacts to these resources (Mitigation Measures 1 through 9). Additionally, the Focused General Plan Update provides policies that would protect sensitive plant and wildlife species, critical habitat, and sensitive vegetation communities in the Project area.

Therefore, projects to be facilitated by the Focused GPU would comply with local policies and ordinances protecting biological resources set forth in the Focused General Plan Update. With incorporation of Mitigation Measures BIO-1 through BIO-9, implementation of the Project would not result in impacts to protected biological resources, and the Project would not conflict with any local policies or ordinances protecting biological resources. Impacts would be less than significant.

6.5.3 Mitigation Measures
Implementation of Mitigation Measures BIO-1 through BIO-9 (described under Thresholds 1 through 4 in Sections 6.1.3, 6.2.3, 6.3.3, and 6.4.3) ensures no significant impacts would occur to biological resources through conducting pre-construction surveys, focused sensitive plant and wildlife species surveys, focused bird species surveys, requiring sensitive vegetation communities impacts mitigation, habitat restoration for temporary impacts, a qualified monitoring biologist during construction, conducting an aquatic resources delineation, and obtaining resource agency permits.

6.5.4 Significance After Mitigation
Implementation of Mitigation Measures BIO-1 through BIO-9 would mitigate all direct and indirect permanent and temporary impacts to biological resources to below a level of significance, and any additional protection measures set forth in the Focused General Plan Update would be implemented, as necessary, thereby resulting in the Project’s compliance with local policies or ordinances.

6.6 Threshold 6: Regional Conservation Planning

6.6.1 Guidelines for Determination of Significance
A significant impact would result if the Project would conflict with the provisions of an adopted Habitat Conservation Plan, Natural Community Conservation Plan, or other approved local, regional, or state Habitat Conservation Plan.

6.6.2 Impact Analysis
The Project area is not within an adopted Habitat Conservation Plan and is not subject to the NCCP program or other regional conservation plan. Therefore, no impacts to local or regional conservation plans would occur from implementation of the Project, and no protection measures are required.

Biological Resources Technical Report 62 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project

6.6.3 Mitigation Measures
No mitigation is required.

6.6.4 Significance After Mitigation
No mittigation is required, therefore impact without mitigation incorporated.

6.7 Cumulative Impacts

6.7.1 Cumulative Threshold 1: Sensitive Plant and Wildlife Species Cumulative projects within the vicinity of the Project area would have the potential to result in impacts to sensitive plant and wildlife species, including loss of habitat.

The remaining areas within Orange County, as well as adjacent and nearby jurisdictions, including Los Angeles County to the north, San Bernardino County and Riverside County to the east, and San Diego County to the south, would be required to comply with applicable federal and state regulations that provide protections for sensitive plant and wildlife species, such as the federal Endangered Species Act, California Endangered Species Act, and the California NCCP Act. In addition, some projects that impact sensitive species require approval from the USFWS and CDFW. If significant impacts occur from particular cumulative projects, then mitigation measures are implemented to reduce impacts to the extent feasible in compliance with CEQA.

As discussed in Section 6.1, development of the Project area would have the potential to impact sensitive plant and wildlife species. Because cumulative projects, would be required to implement project-specific mitigation measures and obtain applicable approval from the CDFW and/or USFWS to reduce the Project’s impacts to sensitive plant and wildlife species to below a level of significance, the Project would not contribute to a cumulatively significant impact. Therefore, the Project’s contribution to impacts on sensitive plant and wildlife species would not be cumulatively considerable.

6.7.2 Cumulative Threshold 2: Riparian Habitat or Other Sensitive Natural Community
Cumulative projects in the vicinity of the Project area would have the potential to result in impacts associated with riparian habitat and other sensitive natural communities through direct and indirect loss or degradation.

The remaining areas within Orange County, as well as adjacent and nearby jurisdictions, including Los Angeles County to the north, San Bernardino County and Riverside County to the east, and San Diego County to the south, would be required to comply with applicable federal and state regulations such as the California Lake and Streambed Alteration Program or the California NCCP Act. These programs provide protections for riparian and other sensitive habitats. In addition, Biological Resources Technical Report 63 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project many projects that affect riparian or other protected habitat types require approval from the USFWS and CDFW. If potentially significant impacts would occur from particular cumulative projects, then mitigation measures would be implemented to reduce impacts to the extent feasible.

As discussed in Section 6.2, development of the Project area would have the potential to impact sensitive vegetation communities. Any projects approved within the City’s jurisdiction would be required to implement project-specific mitigation measures to mitigate the Project’s impacts to riparian habitat or other sensitive communities to below a level of significance. Therefore, the Project’s contribution to impacts on riparian habitat and other sensitive natural communities would not be cumulatively considerable.

6.7.3 Cumulative Threshold 3: Jurisdictional Aquatic Resources Cumulative projects located in the vicinity of the Project area would have the potential to result in a cumulative impact associated with federally or state protected aquatic resources.

The remaining areas within Orange County, as well as adjacent and nearby jurisdictions, including Los Angeles County to the north, San Bernardino County and Riverside County to the east, and San Diego County to the south, would be required to comply with applicable federal and state regulations such as the California Lake and Streambed Alteration Program, Sections 401 and 404 of the CWA, and the Porter-Cologne Act.

Existing regulations would ensure that a significant cumulative impact associated with federally or state protected aquatic resources would not occur. If potentially significant impacts would occur from particular cumulative projects, then mitigation measures would be implemented to reduce impacts as required to meet the regulatory agency’s no-net-loss standard. As discussed in Section

6.3, the Project would avoid impacts to jurisdictional aquatic resources to the greatest extent feasible, providing compensatory mitigation at an approved ratio for unavoidable impacts, and would not contribute to cumulative impacts to jurisdictional aquatic resources as a result. Projects in the City and in surrounding cities are required to comply with existing regulatory requirements and obtain applicable permits from the USACE, RWQCB, and CDFW. Therefore, the Project’s contribution would not be cumulatively considerable.

6.7.4 Cumulative Threshold 4: Wildlife Corridors and Habitat Linkages Cumulative projects located within the vicinity of the Project area would have the potential to result in a cumulative impact associated with wildlife movement corridors and habitat linkages.

The remaining areas within Orange County, as well as adjacent and nearby jurisdictions, including Los Angeles County to the north, San Bernardino County and Riverside County to the east, and San Diego County to the south, would be required to comply with applicable federal and state regulations such as the California NCCP Act, which supports the continued provision of wildlife Biological Resources Technical Report 64 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project movement corridors. If potentially significant impacts would occur from particular cumulative projects, then mitigation measures would be implemented to reduce impacts to the extent feasible.

As discussed in Section 6.4, Threshold 4: Wildlife Corridors and Habitat Linkages, development of the Project would have the potential to impact wildlife corridors or habitat linkages. Any projects would be required to implement project-specific mitigation measures to mitigate the Project’s impacts to wildlife corridors or habitat linkages to below a level of significance.

Therefore, the Project would not contribute to a cumulatively significant impact, and the Project’s contribution would not be cumulatively considerable.

6.7.5 Cumulative Threshold 5: Local Policies or Ordinances Cumulative projects located in the vicinity of the Project area would have the potential to result in a cumulative impact associated with conflicts with local policies or ordinances.

The remaining areas within Orange County, as well as adjacent and nearby jurisdictions, including Los Angeles County to the north, San Bernardino County and Riverside County to the east, and San Diego County to the south, would be required to comply with applicable local policies or ordinances. If potentially significant impacts would occur from particular cumulative projects, then mitigation measures would be implemented to reduce impacts to the extent feasible.

As discussed in Section 6.5, Threshold 5: Local Policies and Ordinances, the Project would comply with local policies and ordinances protecting biological resources in the updated Brea General Plan. A significant cumulative impact associated with a conflict with a local policy or ordinance would not occur. Therefore, the Project, in combination with other cumulative projects, would not result in a significant cumulative impact. The Project’s contribution would not be cumulatively considerable.

6.7.6 Cumulative Threshold 6: Regional Conservation Planning As discussed in Section 6.6.2, the Project area is not within an adopted Habitat Conservation Plan and is not subject to the NCCP program or other regional conservation plan. Therefore, the Project, in combination with other cumulative projects, would not result in a significant cumulative impact from conflicts with regional conservation plans. The Project’s contribution would not be cumulatively considerable.

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Biological Resources Technical Report 66 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Section 7 References
Calflora. 2025. Calflora Database. Accessed April 2026. https://www.calflora.org/ cgi-in/species_query.cgi?where-calrecnum=4428.

CCH. 2025. Consortium of California Herbaria (CCH). Accessed April 2026. https://ucjeps.berkeley.edu/consortium/.

CDFW. 2000. California Wildlife Habitat Relationships System – Blainville’s Horned Lizard (Phrynosoma blainvillii)). Accessed April 2026.
https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=2705.

CDFW. 2025a. California Natural Diversity Database. Commercial version. Accessed November 2025. https://nrm.dfg.ca.gov/File
Handler.ashx?DocumentID=109390&inline.

CDFW. 2025b. Biogeographic Information and Observation System (BIOS). Database. Accessed April 2026. https://apps.wildlife.ca.gov/bios
CDFW. 2025c. California Natural Community List. Accessed December 2025. https://wildlife.ca.gov/Data/VegCAMP/Natural-Communities#sensitive CDFW. 2025d. California Horned Lark (Eremophila alpestris actia). Accessed April 2026. https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=1971.

CDFW. 2025e. Essential Connectivity Areas – California Essential Habitat Connectivity (CEHC). Accessed December 2025. https://data.ca.gov/dataset/essential-connectivityareas-california-essential-habitat-connectivity-cehc-ds620.

City of Brea. 2003. City of Brea General Plan. Adopted August 19, 2003. Accessed November 2025. https://www.cityofbrea.gov/179/General-Plan
CNPS (California Native Plant Society). 2025. Inventory of Rare and Endangered Plants (online edition). Rare Plant Program. Accessed December 2025. http://www.rareplants.cnps.org/.

Holland, Robert F. 1986. Preliminary Descriptions of the Terrestrial Natural Communities of California. California Department of Fish and Game. October.

H2OC Stormwater Program. 2025. Show me my Watershed. Accessed November 2025. https://h2oc.org/show-me-my-watershed/
Shuford, W. D., and Gardali, T., editors. 2008. California Bird Species of Special Concern: A ranked assessment of species, subspecies, and distinct populations of birds of immediate conservation concern in California. Studies of Western Birds 1. Western Field Ornithologists, Camarillo, California, and California Department of Fish and Game, Sacramento.

Thomson, Robert C., Wright, Amber N., and Shaffer, H. Bradley. 2016. California Amphibian and Reptile Species of Special Concern. California Department of Fish and Wildlife and University of California Press. Accessed November. 2025. https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=190325&inline.

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Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Unitt, P., A.E. Klovstad, W.E. Haas, and P.J. Mock. 2004. San Diego County Bird Atlas.

Proceedings of the San Diego Society of Natural History 39. San Diego, California: San Diego Society of Natural History.

USACE (United States Army Corps of Engineers). 2025. Los Angeles District Traditional Navigable Waters. Accessed April 2026.
https://www.spl.usace.army.mil/Missions/Regulatory/JurisdictionalDetermination/Navigable-Waterways/.

USDA (U.S. Department of Agriculture).2019.Web Soil Survey. Natural Resources Conservation Service, Soil Survey Staff. Last modified July 31. Accessed April 2026. http://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm.

USDA. 2025a. Web Soil Survey. Natural Resources Conservation Service, Soil Survey Staff. March

26. Accessed April 2026.
https://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx.

USDA. 2025b. Soil Survey Geographic Database (CA702). Accessed April 2026. https://catalog.data.gov/dataset/soil-survey-geographic-database-ssurgo.

USFWS (U.S. Fish and Wildlife Service). 2010. Coastal California Gnatcatcher (Polioptila californica californica) 5-Year Review: Summary and Evaluation. Carlsbad Fish and Wildlife Office.

U.S. Forest Service. 2025. CalVeg Region 5. Accessed April 2026. https://data.fs.usda.gov/geodata/edw/edw_resources/meta/S_USA.EVMid_R05_CentralC oast.xml
USFWS. 2025a. National Wetlands Inventory Wetland Mapper. Last updated November 30.

Accessed November 2025. https://www.fws.gov/wetlands/Data/Mapper.html.

USFWS. 2025b. Information for Planning and Consultation. Accessed November 2025. https://www.fws.gov/southeast/conservation-tools/information-for-planning-andconsultation/.

USFWS. 2025c. Species Search. Accessed April 2026. https://www.fws.gov/species.

USFWS. 2025d. Critical Habitat. Accessed April 2026.
https://services.arcgis.com/QVENGdaPbd4LUkLV/ArcGIS/rest/services/USFWS_Critica l_Habitat/FeatureServer.

USGS (U.S. Geological Survey). 2025. National Hydrography Data. Accessed April 2026. https://www.arcgis.com/home/webmap/viewer.html?url=https://hydro.nationalmap.gov/a rcgis/rest/services/nhd/MapServer&source=sd.

Western Regional Climate Center. 2025. “Climate of California.” Accessed April 2026. https://wrcc.dri.edu/Climate/narrative_ca.php.

Xerces Society. 2018. A Petition to the State of California Fish and Game Commission.

Accessed November 2025.
https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=161902&inline Biological Resources Technical Report 68 April 2026
Brea 2050: Focused General Plan Update and Brea Core Specific Plan Project Zeiner, D.C., W.F.Laudenslayer, Jr., K.E. Mayer, and M. White, eds. 1988-1990. California's Wildlife. Vol. I-III. California Depart. of Fish and Game, Sacramento, California.

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Appendix A. Figures
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Date: 10/24/2025 - Last saved by: Matthew.Dornbach - Path: J:\Projects\City of Brea\City of Brea GPU & Core SP\Map Docs\BreaGPU_CoreSP\BreaGPU_CoreSP.aprx Los Angeles County
Orange County
Orange County
Riverside County
Los Angeles County
San Bernardino County
Crestline
Rialto
Upland Fontana
Ontario Colton
Chino
Glendale
Pasadena
Monrovia
Burbank
Los Angeles Glendora
Pomona
Walnut
Downey
Long Beach
Torrance Carson
Lake Elsinore
Norco Riverside
Corona
Fullerton Yorba Linda
Anaheim
Santa Ana
P a c i f i c O c e a n Irvine
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Brea Focused General Plan Update and Brea Core Specific Plan Regional Location
Source: ESRI, 2023.
±
Planning Area
!(
^
City of Brea
City of Brea Sphere of Influence
0 5 10 Figure 1
Miles
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57 142
Coyote Hills
Golf Course
Black Gold Golf
Course
Powder Canyon
Open Space
Firestone Boy
Scout
Reservation
Sierra Vista
Elementary
School
t John's
scopal
chool
Friends Chrstn
Middle School
Rose Campus
Downtown
Fullerton
Rowland
Heights
Brea
a Habra
Yorba Linda
Placentia
57 Fullerton
91 142
Vellano Country
Club
Chino Hills State
Park
Yorba Regional
Park
Brea Focused General Plan Update and Brea Core Specific Plan Project Location
Source: Maxar Imagery 2024.
±
City of Brea
Brea Core Specific Plan Area
City of Brea Sphere of Influence
0 0.5 1 Figure 2
Miles
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Figure B
Figure C
Figure D
Figure E
Brea Focused General Plan Update and Brea Core Specific Plan USGS Topographic Map
Source: USGS 7.5 Minute Prado Dam, La Habra, Yorba Linda Quadrangles, 1966, 1974, 1981. ±
City of Brea
Brea Core Specific Plan Area
City of Brea Sphere of Influence
0 0.5 1 Figure 3
Miles
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Source: USGS 7.5 Minute Prado Dam, La Habra, Yorba Linda Quadrangles, 1966, 1974, 1981. ±
City of Brea
Brea Core Specific Plan Area
City of Brea Sphere of Influence
0 1,000 2,000 Figure 3a
US Feet
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Source: USGS 7.5 Minute Prado Dam, La Habra, Yorba Linda Quadrangles, 1966, 1974, 1981. ±
City of Brea
Brea Core Specific Plan Area
City of Brea Sphere of Influence
0 1,000 2,000 Figure 3b
US Feet
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Source: USGS 7.5 Minute Prado Dam, La Habra, Yorba Linda Quadrangles, 1966, 1974, 1981. ±
City of Brea
Brea Core Specific Plan Area
City of Brea Sphere of Influence
0 1,000 2,000 Figure 3c
US Feet
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Source: USGS 7.5 Minute Prado Dam, La Habra, Yorba Linda Quadrangles, 1966, 1974, 1981. ±
City of Brea
Brea Core Specific Plan Area
City of Brea Sphere of Influence
0 1,000 2,000 Figure 3d
US Feet
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Source: USGS 7.5 Minute Prado Dam, La Habra, Yorba Linda Quadrangles, 1966, 1974, 1981. ±
City of Brea
Brea Core Specific Plan Area
City of Brea Sphere of Influence
0 1,000 2,000 Figure 3e
US Feet
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Rowland
Heights
E Chapman Ave
E Lambert Rd
E Imperial Hwy
Coyote Hills
Golf Course
Fullerton City
Golf Course
Sierra Vista
Elementary
School
Downtown
Fullerton
Brea
57 E Orangethorpe Ave
N
East St
Fullerton
Firestone Boy
Scout
Reservation
Sleepy Hollow
N
Rose Dr
Richfield Rd
E Imperial Hwy
Carbon Canyon Rd
S Im perial Hwy
Black Gold Golf
Course
Alta Vista
Country Club
Kingsbriar Park
Olinda Ranch
Neighborhood
Park
Friends Chrstn
Middle School
Rose Campus
Yorba Linda
Placentia
E Orangethorpe Ave
N
Krae
mer Blvd
E La Palma Ave
S Imperial Hwy
Riverdale
Elementary
School Child
Care
142
Vellano Country
Club
Hollow R
Yorba Linda Blvd
La Palma Ave
Chino Hills
Park
Yorba Regional
Park
Brea Focused General Plan Update and Brea Core Specific Plan Soils
Source: Maxar Imagery 2024.
±
0 0.5 1 Figure 4
Miles
City of Brea
Brea Core Specific Plan Area
City of Brea Sphere of
Influence
Soils
Alo Clay
Alo Variant Clay
Anaheim Clay Loam
Anaheim Loam
Apollo, Warm-Calleguas
Complex
Balcom Clay Loam
Blasingame-Rock Outcrop
Complex
Bosanko Clay
Calleguas Clay Loam
Capistrano Sandy Loam
Cieneba Sandy Loam, Eroded
Cieneba-Friant Sandy Loams
Complex
Cieneba-Rock Outcrop
Complex
Cropley Clay
Dam
Fontana Clay Loam
Gaviota-Chumash-Rock
Outcrop Complex
Marina Loamy Sand
Metz Loamy Sand
Mocho Loam
Myford Sandy Loam
Myford Sandy Loam, Eroded
Myford Sandy Loam, Thick
Surface
Nacimiento Clay Loam
Omni Clay
Rincon Clay Loam
Riverwash
Rock Outcrop-Cieneba
Complex
San Emigdio Fine Sandy
Loam
Soper Cobbly Loam
Soper Gravelly Loam
Soper Loam
Soper-Rock Outcrop Complex
Sorrento Clay Loam
Sorrento Loam
Water
Xeralfic Arents, Loamy
Xerorthents Loamy, Cut and
Fill Areas
Yorba Cobbly Sandy Loam
Zaca-Apollo, Warm Complex
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142
Coyote Hills
Golf Course
Black Gold Golf
Course
Powder Canyon
Open Space
Firestone Boy
Scout
Reservation
Sierra Vista
Elementary
School
t John's
scopal
chool
Friends Chrstn
Middle School
Rose Campus
Downtown
Fullerton
Rowland
Heights
Brea
a Habra
Yorba Linda
Placentia
57 91 Riverdale 91
Elementary
School Child
Care
Fullerton
91 142
Vellano Country
Club
Chino Hills State
Park
Yorba Regional
Park
S a n t a A n a R i v e r
Brea Focused General Plan Update and Brea Core Specific Plan Hydrology
Source: National Hydrography Dataset 2025; USFWS 2025; Maxar Imagery 2024. ±
City of Brea
Brea Core Specific Plan Area
City of Brea Sphere of Influence
Aquatic Resource Type
Freshwater Emergent Wetland
Freshwater Forested/Shrub
Wetland
Freshwater Pond
Lake
Riverine
NHD Flowlines
0 0.5 1 Figure 5
Miles
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Brea Focused General Plan Update and Brea Core Specific Plan Vegetation Communities and Land Cover Types
Source: Nature Reserve of Orange County, Jones and Stokes, 1992; Orange County Public Works, 2025; Maxar Imagery, 2023. ±
0 0.5 1 Figure 6
Miles
City of Brea
Brea Core Specific Plan Area
City of Brea Sphere of
Influence
Vegetation Communities
and Land Cover
Agriculture
Annual Grassland
Disturbed
Chaparral
Cismontane Woodland
Coastal Scrub
Freshwater Emergent
Wetland
Fresh Water
Non-Vegetated Channel
Riparian Forest/Scrub
Urban/Developed
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Heights
57 142
Coyote Hills
Golf Course
Black Gold Golf
Course
Powder Canyon
Open Space
Firestone Boy
Scout
Reservation
Sierra Vista
Elementary
School
Saint John's
Episcopal
School
Friends Chrstn
Middle School
Rose Campus
Downtown
Fullerton
Rowland
Heights
Brea
La Habra
Yorba Linda
Placentia
57 91 Riverdale 91
Elementary
School Child
Care
Anaheim
Fullerton
71 91
142
Vellano Country
Club
Chino Hills State
Park
Yorba Regional
Park
Gypsum Canyo
Wilderness
Featherly
Regional Park
Brea Focused General Plan Update and Brea Core Specific Plan Historical Species with Potential to Occur
Source: CNDDB 2025; USFWS 2025; Maxar Imagery 2024.
±
City of Brea
Brea Core Specific Plan Area
City of Brea Sphere of Influence
1-Mile Buffer
Birds
California Horned Lark
Coastal Cactus Wren
Coastal California Gnatcatcher
Golden Eagle
Grasshopper Sparrow
Least Bell's Vireo
Southern California RufousCrowned Sparrow
Yellow-Breasted Chat
Yellow Warbler
Western Burrowing Owl
Invertebrates
Crotch's Bumble Bee
Mammals
Pocketed Free-Tailed Bat
Western Mastiff Bat
Plants
Braunton's Milk-Vetch
Intermediate Mariposa-Lily
Robinson's Peppergrass
Reptiles
Blainville's Coast Horned Lizard
Coast Patch-Nosed Snake
Red-Diamond Rattlesnake
Southwestern Pond Turtle
0 0.5 1 Figure 7
Miles
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Heights
57 142
Coyote Hills
Golf Course
Black Gold Golf
Course
Powder Canyon
Open Space
Firestone Boy
Scout
Reservation
Sierra Vista
Elementary
School
Saint John's
Episcopal
School
Friends Chrstn
Middle School
Rose Campus
Downtown
Fullerton
Rowland
Heights
Brea
La Habra
Yorba Linda
Placentia
57 91 Riverdale 91
Elementary
School Child
Care
Anaheim
Fullerton
71 91
142
Vellano Country
Club
Chino Hills State
Park
Yorba Regional
Park
Gypsum Canyo
Wilderness
Featherly
Regional Park
Brea Focused General Plan Update and Brea Core Specific Plan Critical Habitat
Source: CNDDB 2025; USFWS 2025; Maxar Imagery 2024.
±
City of Brea
Brea Core Specific Plan Area
City of Brea Sphere of Influence
Critical Habitat
Coastal California Gnatcatcher
Santa Ana Sucker
0 0.5 1 Figure 8
Miles
Date: 4/10/2026 - Last saved by: Randy.Deodat - Path: J:\Projects\City of Brea\City of Brea GPU & Core SP\Map Docs\BreaGPU_CoreSP\BreaGPU_CoreSP.aprx 57 142
Black Gold Golf
Course
Coyote Hills
Golf Course
Powder Canyon
Open Space
Firestone Boy
Scout
Reservation
Sierra Vista
Elementary
School
aint John's
Episcopal
School
Friends Chrstn
Middle School
Rose Campus
Downtown
Fullerton
Rowland
Heights
Brea
La Habra
Yorba Linda
Placentia
57 91 Riverdale 91
Elementary
School Child
Care
Fullerton
91 142
Vellano Country
Club
Water Can
NP
Yorba Regional
Park
Brea Focused General Plan Update and Brea Core Specific Plan Wildlife Corridor/NCCPs
Source: CA Dept of Fish and Wildlife ds621, ds622, ds760, ds1073, 2025; Maxar Imagery 2024. ±
City of Brea
Brea Core Specific Plan Area
City of Brea Sphere of Influence
County of Orange Central/
Coastal Subregion NCCP/HCP
Orange County Transportation
Authority NCCP/HCP
California Essential Habitat
Connectivity (CEHC)
Natural Landscape Blocks
Natural Areas Small
Potential Riparian Connections
0 0.5 1 Figure 9
Miles
Appendix E. Revised Figures to Draft PEIR
This page intentionally left blank.

Date: 4/10/2026 - Last saved by: Randy.Deodat - Path: J:\Projects\City of Brea\City of Brea GPU & Core SP\Map Docs\BreaGPU_CoreSP\BreaGPU_CoreSP.aprx 57 142
Black Gold Golf
Course
Coyote Hills
Golf Course
Powder Canyon
Open Space
Firestone Boy
Scout
Reservation
Sierra Vista
Elementary
School
aint John's
Episcopal
School
Friends Chrstn
Middle School
Rose Campus
Downtown
Fullerton
Rowland
Heights
Brea
La Habra
Yorba Linda
Placentia
57 91 Riverdale 91
Elementary
School Child
Care
Fullerton
91 142
Vellano Country
Club
Water Can
NP
Yorba Regional
Park
Brea Focused General Plan Update and Brea Core Specific Plan Wildlife Corridor/NCCPs
Source: CA Dept of Fish and Wildlife ds621, ds622, ds760, ds1073, 2025; Maxar Imagery 2024. ±
City of Brea
Brea Core Specific Plan Area
City of Brea Sphere of Influence
County of Orange Central/
Coastal Subregion NCCP/HCP
Orange County Transportation
Authority NCCP/HCP
California Essential Habitat
Connectivity (CEHC)
Natural Landscape Blocks
Natural Areas Small
Potential Riparian Connections
0 0.5 1 Figure 4.3-5
Miles
Source: De Novo Planning Group, 2026.

J:\Projects\City of Brea\City of Brea GPU & Core SP\Map Docs\BreaGPU_CoreSP\Exports\PEIR Miles
0 0.5
1 Figure 4.13-1 Existing Bikeway Network
Brea 2050: Focused General Plan Update and Brea Core Specific Plan N
Kraemer Blvd
Valley View Ave
Imperial
Hwy
La
mbert
Rd
Harbor Blvd
Golden Ave
Lakeview Ave
Berry St
Fairmon
t
Blvd
Harbor Blvd
Rose Dr
Ohio St Bast
anchury
Rd
Carbon Canyon
Rd
Brea Blvd
Village Center Dr
Palm St
Puente St
Central Ave
Birch St
Placentia Ave
Bastanchury Rd
Associated Rd
State Col
l
ege Blvd
Yorba Linda Blvd
Imperial Hwy
Whittier Ave
Randolph Ave
Wildcat Wy Associated Rd
Flower Ave
57 90
142
90 57
142

L O S A N G E L E S C O U N T Y
O R
A N G

E C O U N T Y

O R A N G E C O U N T Y S A N B E R N A R D I N O C O U N T Y Elm Street
Santa Fe Rd
La Habra
Heights
Placentia
La Habra
Fullerton
Yorba Linda
Chino Hills
Sources: City of Brea; Orange County; ArcGIS Online World Hillshade Map Service. Created by De Novo Planning Group for the City of Brea, April 19, 2024.

LEGEND
Brea City Boundary
Brea Core Boundary
Brea Sphere of Influence
County Boundary
Existing Facilities
Class I - Shared Use Path
Class II - Bike Lane
Class III - Shared Lane
Figure M-5. Existing Bicycle Facilities Kraemer Blvd
La
mbert
Rd
Harbor Blvd
Golden Ave
Berry St Brea Blvd
Palm
Puente St
Central Ave
Birch St
Placentia Ave
Bastanchury Rd
Associated Rd
State Col
l
ege Blvd
Yorba Linda B
Imperial Hwy
Randolph Ave
Wildcat Wy Associated Rd
Flower Ave
57 90
14 Elm Street
Placentia
La Habra
Fullerton
Sources: City of Brea; Orange County; ArcGIS Online World Hillshade Map Service.

LEGEND
Brea City Boundary
Brea Core Boundary
Brea Sphere of Influence
County Boundary
Existing Facilities
Class I - Shared Use Path
Class II - Bike Lane
Class III - Shared Lane
Source: Harris & Associates, 2026c.

J:\Projects\City of Brea\City of Brea GPU & Core SP\Map Docs Miles
0 0.5
1 Figure 4.15-6
Existing Drainage System
Brea 2050: Focused General Plan Update and Brea Core Specific Plan N
Berry Street
Reservoir
Vantor
Figure 1
Existing Water Distribution System Within BCSP Area
Water Impact Study - Brea Core Specific Plan
Imperial Hwy
Lambert Rd
Brea Blvd
Birch St
SR-57
State College Blvd
Madison Way
S Randolph Ave
N Poplar Ave
Orange Ave
Berry St
±
0 0.25 0.5
Miles
LEGEND
Reservoir
Pressure Reducing Valves
Fire Hydrants
Watermain
City of Brea Boundary
Brea Core Specific Plan Area
Parcel
Pump
PZ 515
PZ 540
PZ 560
PZ 575
PZ 605
PZ 700
PZ 725
PZ 790
PZ 830
City of Brea
City of Fullerton
Associated Rd
Berry Street
Reservoir
Vantor
Figure 1
Existing Water Distribution System Within BCSP Area
Water Impact Study - Brea Core Specific Plan
Imperial Hwy
Lambert Rd
Brea Blvd
Birch St
SR-57
State College Blvd
Madison Way
S Randolph Ave
N Poplar Ave
Orange Ave
Berry St
±
0 0.25 0.5
Miles
LEGEND
Reservoir
Pressure Reducing Valves
Fire Hydrants
Watermain
City of Brea Boundary
Brea Core Specific Plan Area
Parcel
Pump
PZ 515
PZ 540
PZ 560
PZ 575
PZ 605
PZ 700
PZ 725
PZ 790
PZ 830
City of Brea
City of Fullerton
Associated Rd
Source: Harris & Associates, 2026b.

J:\Projects\City of Brea\City of Brea GPU & Core SP\Map Docs Feet
0 1,000 2,000 Figure 4.15-7
Sewer System within the Brea Core Specific Plan Area
Brea 2050: Focused General Plan Update and Brea Core Specific Plan N
Sewershed 2
(Fullerton)
Sewershed
3 (Brea)
Sewershed 5
(Rolling
Hills)
Sewershed 6
(Associated)
Location
EX1
Location FUT1
Siphon S-2
Siphon S-1
Briarwood
Lift Station
Brea Creek
Lift Station
Hills Sub-Trunk OCSD Rolling
OCSD Fullerton Brea Trunk Sewer/Fullerton Brea Interceptor OCSD Cypress Sub-Trunk
Vantor
Figure 5
Capacity Deficiencies Within BCSP
Wastewater Impact Study - Brea Core Specific Plan
Fullerton Creek
Brea Creek
±
0 0.25 0.5
Miles
LEGEND
City of Brea Boundary
Parcels
Brea Core Specific Plan Area
Sewersheds
Contributing to Existing Condition Deficiency
Contributing to Near-Term Future Condition Deficiency
No Contribution
Land Use Change in a Deficiency Contributing Parcel
Brea Lift Stations
Siphon
Manholes
Gravity Sewer Pipes
d/D Criteria not met (SMP, 2021)
OCSD Gravity Trunk Sewers
OCFCD Facility
City of Brea
City of Fullerton
Sewershed 2
(Fullerton)
Sewershed
3 (Brea)
Sewershed 5
(Rolling
Hills)
Sewersh
(Associa
Location
EX1
Location FUT1
Siphon S-2
Siphon S-1
Briarwood
Lift Station
Brea Creek
Lift Station
Hills Sub-Trunk OCSD Rolling
OCSD Fullerton Brea Trunk Sewer/Fullerton Brea Interceptor OCSD Cypre
Figure 5
Capacity Deficiencies Within BCSP
Wastewater Impact Study - Brea Core Specific Plan
Brea Creek
±
0 0.25 0.5
Miles
LEGEND
City of Brea Boundary
Parcels
Brea Core Specific Plan Area
Sewersheds
Contributing to Existing Condition Deficiency
Contributing to Near-Term Future Condition Deficiency
No Contribution
Land Use Change in a Deficiency Contributing Parcel
Brea Lift Stations
Siphon
Manholes
Gravity Sewer Pipes
d/D Criteria not met (SMP, 2021)
OCSD Gravity Trunk Sewers
OCFCD Facility
City of Brea
City of Fullerton
Appendix F. Omitted Notice of Preparation Comment Letters This page intentionally left blank.

SENT VIA E-MAIL: September 24, 2025
[email protected]
Joanne Hwang, City Planner
City of Brea, Planning Division,
1 Civic Center Circle,
Brea, CA 92821
Notice of Preparation of a Draft Program Environmental Impact Report (PEIR) for the Brea 2050: Focused General Plan Update and Brea Core Specific Plan (Proposed Project)
(SCH No.: 2025081123)
South Coast Air Quality Management District (South Coast AQMD) staff appreciate the opportunity to comment on the above-mentioned document. Our comments are recommendations on the analysis of potential air quality impacts from the Proposed Project that should be included in the Draft Program Environmental Impact Report (PEIR). Please send a copy of the Draft PEIR upon its completion and public release directly to South Coast AQMD as copies of the Draft PEIR submitted to the State Clearinghouse are not forwarded. In addition, please send all appendices and technical documents related to the air quality, health risk, and greenhouse gas analyses (electronic versions of all emission calculation spreadsheets, air quality modeling, and health risk assessment input and output files, not PDF files). Any delays in providing all supporting documentation for our review will require additional review time beyond the end of the comment period.

CEQA Air Quality Analysis
The Lead Agency is recommended to rely on the guidance provided in the South Coast AQMD’s CEQA Air Quality Handbook and website1 when preparing the air quality and greenhouse gas analyses. It is also recommended that the Lead Agency use the California Air Pollution Control Officers Association’s California Emissions Estimator Model (CalEEMod) 2 software, to quantify
emissions of air pollutants from typical land use development project.

In addition, the South Coast AQMD has adopted regional air quality significance thresholds3as well as localized significance thresholds (LST).
4 If the Lead Agency has not adopted its own
significance thresholds, the Lead Agency is recommended to rely on South Coast AQMD’s adopted thresholds for determining whether the Proposed Project’s air quality and greenhouse gas impacts are significant. It is important to note that the localized analysis can be conducted by either using the LST screening tables or performing air dispersion modeling. 1 South Coast AQMD’s CEQA Air Quality Handbook and other resources for preparing air quality analyses can be found at:
http://www.aqmd.gov/home/rules-compliance/ceqa/air-quality-analysis-handbook. 2 CalEEMod is available free of charge at: www.caleemod.com. 3 South Coast AQMD’s air quality significance thresholds can be found at: https://www.aqmd.gov/docs/defaultsource/ceqa/handbook/south-coast-aqmd-air-quality-significance-thresholds.pdf 4 South Coast AQMD’s guidance for performing a localized air quality analysis can be found at:
http://www.aqmd.gov/home/regulations/ceqa/air-quality-analysis-handbook/localized-significance-thresholds.

Joanne Hwang, City Planner 2 September 24, 2025
The Lead Agency should identify any potential adverse air quality and greenhouse gas impacts that could occur from all phases of the Proposed Project and all air pollutant sources related to the Proposed Project. Air quality and greenhouse gas impacts from both construction (including demolition, if any) and operations should be calculated. Construction-related air quality impacts typically include, but are not limited to, emissions from the use of heavy-duty equipment from grading, earth-loading/unloading, paving, architectural coatings, off-road mobile sources (e.g., heavy-duty construction equipment) and on-road mobile sources (e.g., construction worker vehicle trips, material transport trips, and hauling trips). Operation-related air quality and greenhouse gas impacts may include, but are not limited to, emissions from stationary sources (e.g., boilers and air pollution control devices), area sources (e.g., solvents and coatings), and vehicular trips (e.g., on- and off-road tailpipe emissions and entrained dust). Air quality and greenhouse gas impacts from indirect sources, such as sources that generate or attract vehicular trips, should be included in the analysis. Furthermore, if the Lead Agency elects to rely on South Coast AQMD’s air quality significance thresholds, the emissions from the overlapping construction and operational activities should be combined and compared to South Coast AQMD’s air quality significance thresholds for operation to determine the level of significance.

Also, if implementation of the Proposed Project would require the use of new stationary and portable sources, including but not limited to emergency generators, fire water pumps, boilers, spray booths, etc., one or more air permits from South Coast AQMD will be required, and the role of South Coast AQMD would change from a Commenting Agency under CEQA to a Responsible Agency as defined in CEQA Guidelines Section 15381. The assumptions in the air quality analysis in the Draft PEIR will be the basis for evaluating the air permit(s) under CEQA and imposing permit conditions and limits. Questions about air permit requirements should be directed to South Coast AQMD’s Engineering and Permitting staff at (909) 396-3385.

In addition, CEQA Guidelines Section 15096 sets forth specific procedures for a Responsible Agency, including making a decision on the adequacy of the CEQA document for use as part of evaluating the applications for air permits. For these reasons, the Draft PEIR should include a discussion about any new stationary and portable equipment requiring South Coast AQMD air permits and identify South Coast AQMD as a Responsible Agency for the Proposed Project, if applicable. Also, as set forth in CEQA Guidelines Section 15086, the Lead Agency is required to consult with all Responsible Agencies with discretionary approval power over the Proposed Project. Thus, if air permits are required and South Coast AQMD is identified as a Responsible Agency, please let this comment letter serve as South Coast AQMD’s request to convene a meeting with the Lead Agency as required by CEQA Guidelines Section 15104 to discuss the scope and content of the environmental information that will need to be included in the Draft PEIR.

To assist with identifying ways to minimize air quality impacts from the Proposed Project, the Lead Agency is also recommended to consult and apply the guidance from the California Air Resources Board (CARB) Air Quality and Land Use Handbook: A Community Health Perspective,
5 which is a general reference guide for evaluating and reducing air pollution impacts 5 CARB’s Air Quality and Land Use Handbook: A Community Health Perspective can be found at:
https://www.aqmd.gov/docs/default-source/ceqa/handbook/california-air-resources-board-air-quality-and-land-use-handbook-acommunity-health-perspective.pdf.

Joanne Hwang, City Planner 3 September 24, 2025
associated with new projects that go through the land use decision-making process. CARB has another helpful technical advisory, Strategy to Reduce Air Pollution Exposure Near High-Volume Roadways,
6 which contains additional guidance on strategies to reduce air pollution exposure of Proposed Projects located near high-volume roadways.

Since the Proposed Project is a Specific Plan involving local planning and land use decisions, the Lead Agency is recommended to review and consider applying the recommendations contained in the South Coast AQMD Guidance Document for Addressing Air Quality Issues in General Plans and Local Planning,
7 which includes suggested policies that local governments can use in their General Plans or through local planning to prevent or reduce potential air pollution impacts and protect public health.

Mitigation Measures
In the event that the Proposed Project results in significant adverse air quality impacts, CEQA requires that all feasible mitigation measures that go beyond what is required by law be utilized to minimize these impacts. Any impacts resulting from mitigation measures must also be analyzed.

Several resources to assist the Lead Agency with identifying potential mitigation measures for the Proposed Project include South Coast AQMD’s CEQA Air Quality Handbook,8 South Coast AQMD’s Mitigation Monitoring and Reporting Plan for the 2022 Air Quality Management Plan,9 and Southern California Association of Governments’ Mitigation Monitoring and Reporting Plan for the 2020-2045 Regional Transportation Plan/Sustainable Communities Strategy.10 Health Risk Reduction Strategies
Many strategies are available to reduce exposures, including, but not limited to, building filtration systems with MERV 13 or better, or in some cases, MERV 15 or better is recommended; building design, orientation, location; vegetation barriers or landscaping screening, etc. Enhanced filtration units are capable of reducing exposures. However, enhanced filtration systems have limitations.

For example, in a study that South Coast AQMD conducted to investigate filters, 11 a cost burden
is expected to be within the range of $120 to $240 per year to replace each filter panel. The initial start-up cost could substantially increase if an HVAC system needs to be installed and if standalone filter units are required. Installation costs may vary and include costs for conducting site assessments and obtaining permits and approvals before filters can be installed. Other costs may include filter life monitoring, annual maintenance, and training for conducting maintenance and reporting. In addition, because the filters would not have any effectiveness unless the HVAC system is running, there may be increased energy consumption that the Lead Agency should evaluate in the Draft PEIR. It is typically assumed that the filters operate 100 percent of the time 6 CARB’s Strategy to Reduce Air Pollution Exposure Near High-Volume Roadways, April 2017, available at:
https://ww2.arb.ca.gov/sites/default/files/2017-10/rd_technical_advisory_final.pdf. 7 South Coast AQMD. 2005. Guidance Document for Addressing Air Quality Issues in General Plans and Local Planning.

Available at: http://www.aqmd.gov/docs/default-source/planning/air-quality-guidance/complete-guidance-document.pdf. 8 https://www.aqmd.gov/home/rules-compliance/ceqa/air-quality-analysis-handbook 9 South Coast AQMD’s 2022 Air Quality Management Plan can be found at: http://www.aqmd.gov/home/air-quality/clean-airplans/air-quality-mgt-plan (Chapter 4 - Control Strategy and Implementation). 10 Southern California Association of Governments’ 2020-2045 RTP/SCS can be found at:
https://www.connectsocal.org/Documents/PEIR/certified/Exhibit-A_ConnectSoCal_PEIR.pdf. 11 This study evaluated filters rated MERV 13 or better. Accessed at: http://www.aqmd.gov/docs/defaultsource/ceqa/handbook/aqmdpilotstudyfinalreport.pdf. Also see 2012 Peer Review Journal article by South Coast AQMD:
https://onlinelibrary.wiley.com/doi/10.1111/ina.12013.

Joanne Hwang, City Planner 4 September 24, 2025
while residents are indoors, and the environmental analysis does not generally account for the times when the residents have their windows or doors open or are in common space areas of the project. These filters have no ability to filter out any toxic gases. Furthermore, when used filters are replaced, replacement has the potential to result in emissions from the transportation of used filters at disposal sites and generate solid waste that the Lead Agency should evaluate in the Draft PEIR. Therefore, the presumed effectiveness and feasibility of any filtration units should be carefully evaluated in more detail prior to assuming that they will sufficiently alleviate exposures to diesel particulate matter emissions.

South Coast AQMD staff is available to work with the Lead Agency to ensure that air quality, greenhouse gas, and health risk impacts from the Proposed Project are accurately evaluated and mitigated where feasible. If you have any questions regarding this letter, please contact me at [email protected].

Sincerely,
Sam Wang
Sam Wang
Program Supervisor, CEQA IGR
Planning, Rule Development & Implementation
SW
ORC250826-01
Control Number
Bev Perry
2241 Shadetree Circle
Brea, CA 92821
September 24, 2025
City of Brea
Community Development Department
Planning Division
RE: CEQA Comments for Brea 2050: Focused GPU and BCSP
Dear City of Brea Planning Staff:

As the Brea Core Area develops, and new development is built to the east of the 57 Freeway (bordered by Imperial, Valencia and Lambert), I would like to see the PEIR focus on the lack of transportation options for these areas.

The Orange County Transportation Authority (OCTA) has very little bus service except a line to the Brea Mall area providing transit for Breans, but for any other destination within the area I outlined above, there are no real options to use public transit.

I understand that until some of the projects are built or near completion, the possible ridership numbers that OCTA would need to use to see if new transit lines are feasible won't be available, but once they are, the City of Brea should be primed to work with OCTA on the new routes and stops. Brea should be thinking ahead for where the most advantageous bus stops would be and make sure that land is set aside for those.

Besides bus transportation, make sure that bike lanes are included throughout the City, not only for general passage, but also to get to bus stops. Including The Tracks at Brea and other trails throughout the City in those plans would help.

The impacts of new development in the GPU and BCSP will have city-wide implications - especially for transportation - so the City of Brea should evaluate alternatives and mitigations to lessen or avoid those transportation impacts.

Sincerely,
Bev Perry
From: Glenn Parker
To: Brea2050
Subject: FW: CEQA Comments for Brea 2050: Focused GPU and BCSP Date: Wednesday, September 24, 2025 3:40:25 PM
Attachments: NOP letter for Brea GPU & BCSP 9-24-25.pdf Importance: High
To Whom It May Concern:

I fully endorse the comments made by former Mayor Bev Perry.

In addition I would like our Bike Lanes to be upgraded, in accordance with the Classifications defined by the State of California, to provide for easy identification by motor vehicle drivers and to enhance bicycle rider safety.

Please confirm your receipt of my comments.

Respectfully Submitted,
Glenn Parker
Former Brea Mayor
833 Elkridge Street, Brea, CA 92821
714-671-1515 / 714-803-4072
From: Bev Perry [mailto:[email protected]]
Sent: Wednesday, September 24, 2025 11:52 AM
To: [email protected]
Subject: CEQA Comments for Brea 2050: Focused GPU and BCSP

396 HAYES STREET, SAN FRANCISCO, CA 94102
T: (415) 552-7272 F: (415) 552-5816
www.smwlaw.com
KRISTI T. BASCOM
Urban Planner
[email protected]
September 24, 2025
Via Electronic Mail Only
City of Brea
Community Development Department
Planning Division
Email: [email protected]
Copy to: [email protected]
Re: CEQA Comments for Brea 2050: Focused GPU and BCSP
Dear City of Brea Planning Staff:

On behalf of Hills For Everyone, we are submitting these comments on the Notice of Preparation (NOP) of the forthcoming EIR for the City’s Focused General Plan Update (GPU) and Brea Core Specific Plan (BCSP). Hills For Everyone is a non-profit organization that works to protect, preserve, and restore the environmental resources and natural environs of the Puente-Chino Hills and surrounding areas for the enjoyment of current and future generations. The organization has been working in the region since 1978, and was instrumental in the creation and expansion of Chino Hills State Park, along with the City of Brea.

We have reviewed the NOP and offer the following comments regarding issues that should be evaluated in the EIR. The issues identified in this letter are not intended to be exhaustive, and Hills For Everyone reserves the right to raise other issues during the environmental review process after the EIR is circulated for public review.

The NOP lists many potentially significant probable environmental effects from the Project, including but not limited to impacts related to Aesthetics, Air Quality, Biological Resources, Cultural Resources, Energy, Geology and Soils, Greenhouse Gas Emissions, Hazards and Hazardous Materials, Hydrology and Water Quality, Land Use and Planning, Noise, Population and Housing, Public Services, Recreation, Transportation, Tribal Cultural Resources, Utilities and Service Systems, and Wildfire.

The NOP also states that the EIR will describe a range of reasonable alternatives to the project in accordance with CEQA Guidelines. See NOP p. 5.

City of Brea
September 24, 2025