ing and enforcing compliance. In reviewing and synthesizing the published studies, there were several interpretative challenges. First, the studies may be dated, and their results may not reflect the rapidly changing requirements of the program described in Chapter 4. Second, some studies may not be related to the Clean Water Act's (CWA) Section 404 program but may instead evaluate nonfederal programs. The committee recognized this possibility in drawing its conclusions. Third, these studies may not indicate whether the responsible party was the permittee or a third party; however, it is suspected that most studies were for permittee-responsible mitigation, because third-party mitigation is still the exception and not the rule. Fourth, often it cannot be determined if a mitigation was on-site or off-site or whether the action taken was restoration, creation, or enhancement. The committee is therefore reluctant to draw specific conclusions about mitigation in the current Section 404 program based on these studies. However, the committee also drew on its field visits, on testimony from presenters at its meetings, and on the collective experiences of committee members. By cautiously integrating these various perspectives with the literature, compliance can be characterized.
Mitigation plan development begins with a functional assessment of the impact site and continues through the selection and development of a mitigation site leading to the replacement of the impacted site 's functional values. While this is the expected scenario, testimony provided at committee meetings indicates that, in many cases, permit files sometimes lack a mitigation plan, and at times, mitigation may not be required to replace wetland impacts. Performance standards were often unspecified or vague and not directly related to the measurement of the sites' overall performance (Zedler 1998). The committee heard testimony that in some cases mitigation plans do not specify the most basic requirements for a wetland: water source, water quality, water retention, water quantity, soil, and topography, structure (flora and fauna), and location. Absent such basic considerations, adequate performance is unlikely.
Mitigation plans, when clearly written, specify the area of wetland to be lost and the measures proposed for reducing the impact of that loss. The literature suggests that mitigation plans (particularly for older projects) are not always required for each permit (Table 6–1). On a national basis there is an anticipated gain of 78% in wetland area as a result of mitigation. However, results of independent scientific reviews suggest