Johnson County Stormwater Management Program—Shifting Focus from Flood Mitigation to Achieving Multiple Water Quantity and Quality Goals

Johnson County, Kansas, an urban fringe county of the Kansas City metropolitan area, has a current population of over 540,000 and an average annual growth rate of 10,000 people per year. Since establishing a Stormwater Management Program in the early 1990's, Johnson County has conducted county-wide studies to identify flooding problems and implemented numerous flood mitigation projects. Over the past 18 plus years, the program has helped fund over $200 million in flood mitigation projects across the county, removing numerous habitable buildings from the floodplain, improving road crossings, and improving stormwater conveyance. In 2004, Johnson County and 12 NPDES Phase II cities within Johnson County were issued their first NPDES Phase II permit by the Kansas Department of Health & Environment (KDHE). It was clear at that time that the stormwater program should be refined to include consideration of both water quantity and water quality. Over the last 5 years, Johnson County has engaged in numerous efforts to support local and regional efforts to address stormwater quality and quantity. This paper explores programs that have been initiated to achieve a variety of goals including: better characterization of existing water quality in Johnson County; improving regional stormwater Best Management Practices (BMP) standards; monitoring of BMPs; participation in multi- jurisdiction watershed initiatives; increasing public education and involvement; and supporting city efforts to address water quality and quantity. Detailed information on these programs, overall costs, staff requirements, and lessons learned will be provided to help other similar programs effectively implement a comprehensive stormwater program that can address both water quantity and quality.