City of Laguna Beach
Laguna Canyon Creek — Long-Term Management and Maintenance Plan Facility/Area
The project area consists of the natural bottom channel and adjacent floodplain of Laguna Canyon Creek at 20612 Laguna Canyon Road. Laguna Canyon Creek project reach(es), including culvert areas, channel segments, and adjacent interfaces where applicable.
Project/Permit Reference: San Diego Regional Water Quality Control Board (RWQCB) 401 Water Quality Certification No. R9-2019-0017 (Laguna Canyon Creek Erosion Control and Restoration Project). 285 Specs-Section G All Permits.pdf
Mitigation Areas Covered: On-Site mitigation area(s) at/near 20612 Laguna Canyon Road and Off-Site mitigation/enhancement area(s) as identified in the certification/mitigation plan and future recorded deed restriction boundaries.
Purpose
The purpose of this LTMP is to ensure the on-site and off-site mitigation areas are managed, protected, and maintained in perpetuity to preserve hydraulic function, water quality, and habitat values following completion of project improvements, consistent with RWQCB Certification No. R9-2019-0017 and the approved mitigation/monitoring requirements.
Maintenance activities will be limited to those that support mitigation success and beneficial uses (e.g., debris removal, exotic/invasive control, replacement of dead natives, and remedial measures necessary to maintain performance standards).
Performance Standards / Success Criteria (Applied to Both Sites) The City will manage both the on-site and off-site mitigation areas to meet and maintain the following success criteria:
Success Criteria (Vegetation / Ground
Cover)
Standard
% Cover of Native Plant Species ≥ 80%
% Cover of Non-Native Plant Species < 5% (annual exotics must not exceed 5%) % Cover of Bare Ground < 20%
% Cover of Litter N/A (tracked qualitatively; removed during inspections) Note: The certification requires the mitigation site(s) be maintained free of specified perennial exotic species and limits annual exotics to ≤5%.
Inspection Schedule & Responsible Parties (On-Site + Off-Site) Routine Inspections (City):
• Quarterly inspections (minimum) by City (or City’s maintenance contractor) for: trash/debris, access constraints, erosion/scour concerns, invasive regrowth, irrigation issues (if present), and any encroachments.
Targeted Inspections (City):
• Pre-storm inspections prior to major forecasted storm events (and post-storm follow-up as needed) focused on culverts, channel pinch points, and areas where debris or vegetation could mobilize and impair flows.
Annual Compliance/Monitoring Inspections (Qualified Biologist / Consultant):
• Annual monitoring sufficient to evaluate performance criteria trends, photo points, and any needed remedial measures, consistent with annual reporting expectations under the certification.
Attachment 3
15 Routine Debris and Obstruction Removal
The City will conduct periodic inspections of the creek corridor and remove trash, litter, and other abiotic debris that could obstruct flows or degrade water quality. Particular attention will be given to culverts, bridge crossings, and channel pinch points where debris accumulation could increase the risk of flooding or blockages during storm events. Debris removal activities will follow established City waste management practices, including separation of green waste for City disposal and appropriate removal of non-green waste by contractors when necessary. All activities will be conducted in a manner that prevents discharge of pollutants to the creek or municipal storm drain system.
Vegetation Management
Selective vegetation management will be performed to maintain channel conveyance while preserving native vegetation communities. Maintenance activities may include pruning of dead or damaged vegetation, removal of woody overgrowth that restricts hydraulic capacity, and trimming of vegetation where appropriate. Native plant communities will be preserved to the maximum extent feasible, and unnecessary removal of non-woody native species will be avoided. In areas near the erosion protection improvements adjacent to the Pacific Marine Mammal Center and the City Animal Shelter, cattails may be selectively thinned approximately every two years, limited to 10–20 percent of the population in staggered sections and cut above ground level to maintain ecological habitat while preserving hydraulic performance. Routine trimming will be conducted using hand tools (e.g., hand pruners, loppers, weed whips) where practicable to minimize disturbance. The use of heavy equipment (e.g., mowers, tractors, and excavators) will be limited to situations where necessary for safety or functionality and will be conducted in a manner that minimizes impacts to mitigation areas and water quality, consistent with applicable permit requirements. Vegetation management activities will be scheduled outside of the nesting bird season (generally February 15 through September 1) whenever feasible; if work must occur during this period, appropriate biological review and clearance measures will be implemented in accordance with permit conditions and best management practices.
Sediment Management for on- and off-site areas will be implemented to prevent sediment discharge.
Management will help minimize ground disturbance and stabilize exposed soils. Good housekeeping and spill prevention measures will be maintained to avoid the release of hazardous materials.
Invasive Species Control
The City will implement targeted removal and control of invasive plant species within the creek corridor to protect native habitat. In mitigation areas associated with project permits, maintenance will be limited to activities that support ecological success, including trash and debris removal, invasive species control, and remedial actions necessary to maintain habitat performance standards.
The City will implement targeted removal and control of invasive plant species within the creek corridor to protect native habitat and maintain success criteria. In mitigation areas, maintenance will be limited to activities that support ecological performance, including invasive species control, trash and debris removal, and necessary remedial actions. Removal methods may include hand pulling, weed whipping, herbicide application, or other City-approved techniques, with direction provided by the City regarding target species, locations, and timing to avoid impacts to native vegetation; all plant material, including roots, will be removed where feasible. Herbicide use will be restricted to non-native species only, with no application on native vegetation. The Contractor shall provide advance notice prior to any herbicide or pesticide application, including proposed application times, and applications will not occur on weekends or legal holidays without City approval. Application will be limited to suitable weather conditions. All removed invasive plant material will be disposed of off-site in a manner that prevents re-establishment. These measures are intended to protect water quality and ensure the long-term integrity of mitigation areas. 16 Pre-Storm Inspection and Storm Readiness
Prior to major forecasted storm events, the City will conduct inspections of the creek channel, culverts, and related drainage infrastructure. These inspections will focus on identifying and removing accumulated debris or vegetation that could mobilize during storm flows and create downstream blockages.
Maintenance activities will also ensure that materials, equipment, and waste are properly secured so that storm runoff does not transport pollutants into the creek. Any channel maintenance work will be limited to the minimum extent necessary to maintain hydraulic function and will follow applicable permit conditions.
Documentation and Monitoring
The City will provide for the long-term management of both on-site and off-site mitigation areas through a dedicated maintenance operations and maintenance budget, ensuring ongoing funding to support sustainability and compliance with applicable requirements. The City will document site conditions before and after maintenance activities to support ongoing monitoring. These records will be compiled into periodic summaries and retained for documentation and reference. Through implementation of this Long-Term Management Plan, the City of Laguna Beach will maintain the hydraulic performance, environmental quality, and habitat values of Laguna Canyon Creek while ensuring compliance with applicable regulatory permits. 17 18
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