Introduction
Canyon Loop Trail Improvement Project
Habitat Mitigation and Monitoring Program 4
1.4 Summary of Impacted Areas
The Project has resulted in the permanent removal of vegetated habitat directly adjacent to the existing trail. However, in most areas, the trail is already generally wide enough for the Project’s goals, resulting in minimal need for additional widening and very minimal disturbance to surrounding vegetation. Acreages of vegetation communities that will be permanently lost as a result of this project are presented in Table 1, below.
Table 1: Summary of Impacts to Vegetation Communities
Vegetation Communities Permanent Impacts (acres)*
California Sagebrush – Black Sage
Scrub 0.02
Coast Live Oak Woodland and Forest 0.01
Coast Prickly Pear Scrub1 0.02
Disturbed 0.20
Disturbed California Sagebrush –
Black Sage Scrub 0.07
Scrub Oak Chaparral 0.01
TOTAL 0.31
*Total may not sum due to rounding.
The California Department of Fish and Wildlife (CDFW) reviewed the Project’s Mitigated Negative Declaration (MND) and provided a comment letter to the City of Diamond Bar on November 13, 2020 (Appendix A, CDFW Comments on Canyon Loop Trail Improvement Project). Comment #2 required that the City of Diamond Bar mitigate the permanent loss of sensitive vegetation communities as described in the California Natural Community List (CDFW 2021). Of the on-site vegetation communities that could support the federally threatened coastal California gnatcatcher (CAGN; Polioptila californica californica), CPPS (Holland Equivalent: Diegan Coastal Sage Scrub; Code: 32500) is considered a sensitive (S3) community by the CDFW requiring mitigation. To comply with this request, Michael Baker contacted the nearby Soquel Canyon Mitigation Bank (SCMB) on behalf of the City of Diamond Bar to determine if mitigation credits for the loss of 0.05 acre2 of CPPS were available. The SCMB does not have any remaining credits to mitigate for the loss of this community. As a result, the City of Diamond Bar has agreed to mitigate for the loss of CPPS through on-site restoration at an anticipated 5:1 ratio. The permanent impacts for the proposed Canyon Loop Trail Improvement Project and the CDFW required mitigation acreage and ratio are identified in Table 2, below.
1 State Rarity Rank S3 Sensitive Natural Community (California Department of Fish and Wildlife [CDFW] 2021). 2 0.05 acre of loss of CPPS was proposed based on original impact estimates. Following construction activities, impacts to CPPS were determined to be less than originally anticipated, totaling 0.02 acre.
Introduction
Canyon Loop Trail Improvement Project
Habitat Mitigation and Monitoring Program 5
Although it is not considered a sensitive community by CDFW, CSBSS (S4, Holland Equivalent: Diegan Coastal Sage Scrub; Code: 32500) and Disturbed California Sagebrush – Black Sage Scrub (DCSBSS) have potential to support CAGN. As a result, the City of Diamond Bar has agreed to mitigate for the loss of CSBSS/DCSBSS through on-site enhancement at an anticipated 1.5:1 ratio. The permanent impacts for the proposed Canyon Loop Trail Improvement Project and the CDFW required mitigation acreage and ratio are identified in Table 2, below.
Table 2. Mitigation Summary
Project Impact Impact Area
(acres) Mitigation Type/Location Mitigation Area (acres) Mitigation
Ratio
Permanent
Impact to CPPS 0.02 On-site (within Summitridge Park)restoration of CPPS 0.10-acre CPPS 5:1 Permanent
Impact to
CSBSS
0.02 On-site (within Summitridge Park)
Enhancement of CSBSS 0.03-acre CSBSS 1.5:1
Permanent
Impact to
DCSBSS
0.07 On-site (within Summitridge Park)
Enhancement of CSBSS 0.11-acre CSBSS 1.5:1
Total 0.11 On-site restoration of CPPS / Onsite Enhancement of CSBSS
0.10- acre CPPS /
0.14-acre CSBSS 5:1 / 1.5:1
Canyon Loop Trail Improvement Project
Habitat Mitigation and Monitoring Program 6
Section 2 RESTORATION GOALS
The purpose of this Program is to define the restoration goals and approach to the restoration of CPPS and enhancement of CSBSS for the Canyon Loop Trail Improvement Project.
2.1 Responsibilities
The City will be responsible for the funding of the restoration and enhancement effort and acquiring staff to implement the Project. The City will be consulted annually with the submission of monitoring memos. The City will be included with the regulatory agencies for the final approval of the project in Year 5.
The installation contractor and restoration maintenance contractor shall both be experienced with restoration and enhancement projects to act in the best interest of the native vegetation and wildlife within the area. The Project Restoration Ecologist shall be familiar with the Project and experienced working within the City.
2.2 Type(s) and Area(s) to be Established, Restored, Enhanced, and/or Preserved
The Program consists of the restoration of an overall 0.10-acre of disturbed uplands within Summitridge Park in the City of Diamond Bar (refer to Figure 3, Restoration Project Site).
Restoration will consist of restoring the Project Restoration Site with a native plant palette and removing exotic species. The Project Restoration Site is located approximately 900 feet to the northeast of the Project site impact area. The Project Restoration site generally consists of exotic upland forbs and remnant patches of disturbed coastal sage scrub (DCSS).
The Program also consists of the enhancement of an overall 0.14-acre of DCSBSS within Summitridge Park in the City of Diamond Bar. The enhancement activities will take place in two separate sites, Site A (0.05-acre) and Site B (0.09-acre), both located along Canyon Loop Trail (refer to Figure 4, Enhancement Project Sites). Enhancement will consist of enhancing the Project Enhancement Sites with a native plant seed palette and removing exotic species.
The Project Enhancement Sites are located adjacent to the Project site impact area, and generally consist of black sage (Salvia mellifera), California sagebrush (Artemisia californica), and exotic upland forbs.
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34.00372
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34.005713
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Restoration Project Site
Figure 3
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Restoration Project Site (0.10 acre)
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CANYON LOOP TRAIL IMPROVEMENT PROJECT
HABITAT MITIGATION AND MONITORING PROGRAM
Source: Nearmap (05/2022)
Ridge Route Trail
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Enhancement Project Sites
Figure 4
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Enhancement Project Sites (0.14 acre)
!> Reference Point
CANYON LOOP TRAIL IMPROVEMENT PROJECT
HABITAT MITIGATION AND MONITORING PROGRAM
Source: Nearmap (05/2022)
Canyon Loop Trail
Site A
Site B