Since its initial passage in 1972, the Clean Water Act has attempted to restore and protect our Nation's waters. The definition of `our Nation's waters' has undergone periodic debate and scrutiny as the U.S. Environmental Protection Agency, the U.S. Army Corps of Engineers, and the Supreme Court have defined and redefined the standards for determining CWA jurisdiction. The Supreme Court's most recent set of standards, including the "significant nexus" test, appear to both increase the uncertainty in what is regulated and increase the burden of proof for determining CWA jurisdiction. The Arid West was singled out in the most recent EPA and Corps joint jurisdictional guidance as a problematic area. Focusing on the Arid West, my dissertation evaluates the CWA jurisdiction process from three perspectives: law, policy, and science, and explores an understanding of the past, present, and potential future path of CWA jurisdiction.

I analyzed Corps jurisdictional determinations from their national database. The data showed that the Corps has reversed their trend of issuing the complex and often time intensive Approved Determination to the expeditious Preliminary Determination that affords the same protection to an aquatic resource with reduced effort, and showed that the number of determinations disclaiming jurisdiction have returned historical levels. Also, the data showed that some local Corps offices do not mirror the national trends. In exploring the current state of stream research, the data showed a parallel in the timing of the Supreme Court Cases and subsequent guidance to increases in the number of articles published. In addition, the data showed that research on Arid West streams have focused on a smaller set of functions and services as compared to all potential stream functions. Using readily available tools and peer reviewed methods, I have proposed a delineation process that would bring transparency and consistency to the Approved JD process. Data showed that these tools and methods produce meaningful results in an Arid West watershed. The current CWA jurisdictional guidance can still meet the primary objective of the Act within the current policy framework and through the incorporation of existing tools into the determination process.