PROCEDURAL GUIDANCE FOR EVALUATING WETLAND MITIGATION PROJECTS IN CALIFORNIA'S COASTAL ZONE
A variety of alternatives exist for mitigating the adverse affects of wetland development projects. This document focuses on in-kind compensatory wetland mitigation, which includes creation, restoration, or enhancement of wetland habitat and functions as compensatory mitigation for adverse impacts to existing wetlands. Out-of-kind mitigation is a special type of compensatory mitigation in which the adverse impacts to one habitat type are mitigated through the creation, restoration, or enhancement of another habitat type.14
The process by which the habitat and functions at the affected site are compared to the habitat and functions at the proposed mitigation site is central to any application of out-of-kind mitigation. This process involves the comparison of dissimilar habitats, and is required to determine the type and amount of compensatory mitigation required. Depending on the habitats, these comparisons can be relatively direct (e.g., fishes in a subtidal marine habitat compared to fishes in an open-water estuarine habitat) or quite extreme (e.g., fishes in a subtidal marine habitat compared to birds in a saltmash).
Several techniques have been developed to compare dissimilar habitats. Two techniques applied to wetlands in the coastal zone are the Habitat Evaluation Procedure (HEP) developed by the U.S. Fish and Wildlife Service, and the Biological Evaluation Standardized Technique (BEST) developed by MEC Analytical Systems, Inc. for the Port of Los Angeles (MEC, 1988). These procedures can be quite complex and include evaluation criteria that are both objective and subjective. To date, no one process for comparing dissimilar habitats is fully accepted by the resource and regulatory agencies having an active role in the coastal zone. And regardless of the process used, such assessments often yield ambiguous results and are often time-consuming. As a result, the type of mitigation habitat is usually determined relatively early in the development of an out-of-kind mitigation plan. Results from the comparative analysis of dissimilar habitats are then used to help justify the appropriateness of the selected mitigation habitat.
Information from the ecological comparison of dissimilar habitats is also used to determine the appropriate mitigation ratio. As mentioned previously, the mitigation ratio is the ratio of values gained per unit area to values lost per unit area. For out-of-kind mitigation ratios, information from the comparative analyses can be used as a way to calculate the functional value of various attributes present in each habitat. These calculations are designed to provide value-per-unit-area results that are comparable among different habitat types. Obviously, this is not a straightforward process, and numerous assumptions go into these calculations. CCC staff must proceed cautiously in evaluating the results of such an analysis.
Once the type of mitigation habitat and the mitigation ratio are determined, it is possible to apply many of the procedures for mitigation plan development and project evaluation described in this document. What differs from the procedures described for in-kind mitigation are the order in which the major elements are considered and the process by which the goals, objectives, and performance standards are developed (see Figure 1 and Section IV, Part 2). Much of the initial work to develop a plan for out-of-kind mitigation will focus on determining the type of project, its location, and the mitigation ratio. Thus, the mitigation attributes (item 3 in Figure 1 and Section IV, Part 3) will often be addressed first in out-of-kind mitigation.
Once the mitigation attributes are determined it should be possible to follow the framework outlined for in-kind mitigation beginning with step one, the ecological assessment. However, since the adversely affected and mitigation habitats are dissimilar in out-of-kind mitigation, an ecological assessment of the affected site will have limited utility in determining the goals, objectives, and performance standards for the mitigation project. Instead, the initial ecological assessment should be completed at one or more reference sites that exhibit some or all of the functions of the intended mitigation habitat. Information from an ecological assessment of the reference sites is then used in the development of the goals, objectives, and performance standards for the mitigation project. In addition, the monitoring plan should include concurrent monitoring of the mitigation and reference sites to provide the appropriate data for evaluating performance. Finally, establishing a technical advisory group early on in the process can increase the probability of achieving successful mitigation. The Lone Tree Slide case study, below provides an example of a technical advisory group's role.
As this discussion illustrates, out-of-kind mitigation raises special problems for which there are no simple solutions. Although the process outlined above can help in devising a plan for out-of-kind mitigation, it does not, nor is it intended to, address all of the issues associated with this type of mitigation. CCC staff should proceed carefully in both the review of proposed plans and in evaluating the performance of out-of-kind mitigation projects.
14For an example of a coastal development permit including both in-kind and out-of-kind compensatory mitigation see: CCC, 1991.
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Mitigation Plan Development and Evaluation
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Evaluating the Performance of noncompensatory Wetland Restoration Projects
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