Mitigation evaluation study for the south Texas coast, 1975- 1986.

In recent years the U.S. Fish and Wildlife Service (Service) has perceived a need to assess the effectiveness of its recommendations for mitigation of adverse impacts to fish, wildlife, and their habitats. The purpose of this report was to evaluate mitigation efforts associated with U.S. Army Corps of Engineers Section 10/404 permits regulating wetland development in the South Texas. The report was designed to substantiate beneficial recommendations and to provide support and direction for changes in less successful ones. The report evaluates the levels of acceptance (incorporation into project plans or issued permits), implementation, and success of Service recommendations made for 59 permitted projects. Major types of mitigation, including avoidance of impacts, water quality, and habitat restoration and compensation (enhancement and creation) projects were inspected during field surveys at the 59 sites. Habitat compensation included smooth cordgrass, black mangrove, and seagrass transplantations onto naturally-unvegetated substrates or into areas where uplands had been excavated. Statistical analysis of stem density and/or cover were used to examine differences between man-made smooth cordgrass marshes and nearby natural controls. Measurements of cover and species composition within transplanted seagrass beds were compared to the same parameters in adjacent natural grassbeds. In addition to vegetative comparisons, the existing areal extent of compensation projects was determined in relation to the area required by the permit. The results of this study indicated a 78% unconditional acceptance, 5% rejection, and 16% modification of Service recommendations with the fate of the remaining one percent unresolved. Recommendations designed to avoid impact to wetlands or assure adequate water quality within excavated canals had the highest level of implementation and success. Habitat compensation projects had less favorable results which were ascribed to imprecise mitigation plans and poor site selection and preparation. Noncompliance with permit conditions was found at 31% of the sites inspected. Seventy-eight percent of the non-compliance observed was unfulfilled mitigation requirements with the remaining 22% being additional unauthorized work. Results of the mitigation efforts evaluated in South Texas, including the acreage impacted and replaced, and observation of non-compliance are analyzed in the report.