Compensating for Wetland Losses Under the Clean Water Act (2001)
Chapter: Appendix D California Department of Fish and Game, South Coast Region; Guidelines for Wetland Mitigation
Appendix D
California Department of Fish and Game, South Coast Region; Guidelines for Wetland Mitigation
Contributed by William E.Tippets, Habitat Conservation Supervisor, California Department of Fish and Game, South Coast Region
These ratios should be considered as general guidelines for mitigation for impacts to streams and associated habitat.
|
1:1 |
Low-value habitat |
E.g., isolated freshwater marsh, unvegetated streams. |
|
2:1 |
Medium-value habitat |
E.g., disturbed mulefat scrub, highly disturbed willow riparian. |
|
3:1 |
High-value habitat |
E.g., willow riparian, possibly with some exotics, rare/unique habitats. |
|
5:1 |
Endangered species habitat |
E.g., mature willow riparian with least Bell's vireo. |
|
5:1 |
Impacts beyond permitted in the SAA/violations |
This can vary, depending on the quality, temporal loss, location, etc., but should have a compensatory factor in addition to the above guidelines of 1:1 to 5:1. |
Other considerations:
It is important to consider “no net loss to wetlands.” Streams should be considered under this no-net-loss policy to ensure that adequate creation is represented (rule of thumb, a minimum of 1:1 of their mitigation for permanent impacts should include creation). Creation, restoration,
and/or enhancement could make up the balance of the mitigation measures. Preservation is usually looked at as a recommended avoidance measure, but preservation and protection of significant wetlands can be part of the entire project's measures to be considered. Instances involving lower-quality habitat impacts may be mitigated by nonnative exotic plant removal.
Freshwater marsh restores more successfully than a multilayered willow riparian community, which may have a significant temporal loss component in its mitigation requirements.
Temporary impacts should preferably be restored on-site and should account for mitigation for the temporal loss.
The above ratios consider acreage of impact. Individual tree ratios/ requirements can be incorporated as part of the plan to ensure sufficient mitigation. Also, guidelines for impacts to individual mature oak and sycamore trees are mitigated based on the size of tree impacted, at appropriate planting centers and with appropriate native understory. This may require the applicant to obtain additional land beyond that required for the habitat acreage requirement as described above.
