| Mitigation Planning |
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Compensatory Wetland Mitigation
Compensatory wetland mitigation is required by both the Oregon Department of State Lands (DSL) (OAR 141-085-0126 through 0660) and U.S. Army Corps of Engineers (Corps) whenever authorized activities result in permanent impacts to wetlands. Sometimes compensatory mitigation can be provided through use of mitigation banks or fee in-lieu (also known as ‘payment-to-provide’ to DSL). DSL and the Corps distinguish temporary and permanent impacts. Typically, impacts or effects that do not result in the permanent loss of function and/or area and are rectified within one year of project completion, are considered temporary for which compensatory mitigation is not required (refer to OAR 141-085-0010(208)).
For a list of existing mitigation banks serving Oregon, refer to the DSL website: http://www.oregon.gov/DSL/PERMITS/mitbank_status.shtml
The current cost per acre of payment-to-provide fees for DSL is $75,000/acre (updated April 2007), based on the average cost per mitigation bank credit statewide.
If banking or payment-to-provide is not an option, on or off-site mitigation is required. To be successful mitigation planning requires good site selection, planning, construction (e.g., grading, planting), and monitoring. The plan for on or off-site mitigation is called a Compensatory Wetland Mitigation Plan (CWMP).
| NOTE: DSL has different OARs governing mitigation for freshwater versus estuarine impacts. |
ODOT has developed a CMP Document Template and CMP completeness checklist for freshwater wetland mitigation. The intent is to provide a level of consistency for ODOT documents. If you need to mitigate for the loss of estuarine wetlands, please contact ODOT staff for guidance and example documents.
There are six major elements of CMP implementation:
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Development of Goals, Objectives, and Success Criteria |
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Formulation of the plan which can include grading, hydrologic modifications, and planting. Please note that design of a wetland mitigation site can be complex and challenging. Engineers, biologists, regulatory specialists, and ODOT project leads will need to work together to develop a successful site plan |
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Construction of the plan elements |
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Post Construction Monitoring and implementation of contingency measures of needed |
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| Riparian Mitigation |
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Although less formal in process, the DSL and Corps staff expect that mitigation for permanent impacts to riparian vegetation also be described during the permit process. A loss of riparian vegetation can affect waters of the state/U.S. This is especially the case for affects to native woody vegetation.
Generally, mitigation for riparian impacts is limited to replacement of woody vegetation at a 2:1 ratio. However, for special cases or larger impacts, ODOT has developed a Riparian Mitigation Document Template, which is a scaled down version of the CMP. This template should only be prepared for larger impacts which can not be succinctly addressed in the permit application.
Many of the same concepts of CMP development are applicable to riparian communities. However, the function and value assessment is less rigorous and it is assumed that replacement or improvement of the vegetative community will mitigate for lost functions.
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