A review of the Missouri Department of Natural Resources (MDNR), Water Pollution Control Program (WPCP) compliance and enforcement program was conducted by the Environmental Protection Agency (EPA), Region 7, Water Enforcement Branch (WENF) on September 18-22, 2006. MDNR is the state agency with the authority to administer the federal National Pollutant Discharge Elimination System (NPDES) program in Missouri. The review consisted of a program overview questionnaire, file reviews, conversations with MDNR program staff, and visits to the departments regional offices and the central office. EPA staff conducted file reviews in the following MDNR offices: the Southwest Regional Office in Springfield (SWRO), the Southeast Regional Office in Poplar Bluff (SERO), the St. Louis Regional Office (SLRO), the Kansas City Regional Office in Lees Summit (KCRO), and the MDNR Central Office located in Jefferson City. EPA staff reviewed 146 files of Missouri permittees and facilities. The state program review focused on the CWA NPDES program. The 146 files were reviewed by EPA to determine how MDNR implements its authorized CWA NPDES program. The review focused on MDNR enforcement response in federal fiscal year (FY) 2005; while some violations which occurred prior to FY2005 were also examined in order to assess the rationale for enforcement sought during FY2005.