Habitat loss, cumulative impacts, and the Clean Water Act Section 404 program: A spatial analysis

Habitat loss is the leading cause of species extinctions and biodiversity reduction in the world today. This dissertation quantified cumulative habitat loss associated with Clean Water Act Section 404 permits, primarily for developments, issued by the U.S. Army Corps of Engineers. First, I evaluated the existing 404 data set within the San Jacinto and Santa Margarita Watersheds. From 1984--2003, at least 304 acres of waters of the U.S. were permanently impacted, including 91 acres of wetlands, and at least 450 acres of mitigation were required for authorized developments. However, the existing 404 data did not contain enough information to adequately evaluate cumulative impacts.; I used remote sensing and GIS techniques to quantify cumulative habitat loss over time. The results of this analysis show the majority of habitat loss occurred outside of explicitly-404-authorized developments. While impacts explicitly authorized by the Corps under Section 404 were relatively small in relation to total cumulative impacts, non-explicitly-authorized development cumulatively represents a substantial fraction of observed habitat loss, including impacts to waters of the U.S. Based on this analysis, the Corps has failed to adequately analyze cumulative impacts, despite legal requirements to do so.; The spatial distribution of habitat loss and 404 permits were analyzed statistically (accounting for spatial autocorrelation). In almost all cases, percent habitat loss was significantly correlated with variables representing 404 authorizations. Significant correlations may indicate the presence of non-explicit/indirect authorizations and that 404-authorizations may indirectly facilitate nearby development (i.e., growth inducing impacts).; This study expanded the usage of remote sensing, GIS, and spatial statistics for the purpose of regulatory-driven cumulative impact assessment and provides a model for future cumulative impact assessment studies seeking to analyze spatially-distributed impacts of permit and other regulatory, policy, or legislative decisions. Until resource agencies quantify cumulative impacts in a spatially explicit manner and analyze those data statistically, there can be little rigorous scientific basis for formulating regulatory or policy decisions regarding cumulative impacts.