Sedgwick County, Kansas
Water Resources Solutions and partners completed a watershed study for the 32-square-mile Spring Creek Basin in Sedgwick County, Kansas, which includes the cities of Derby and Wichita. The study focused on identifying water quantity and quality issues, developing various alternatives to resolve them, public involvement in the process, and recommendations for specific actions. The plan addressed the nine minimum elements of a watershed plan as defined by the Environmental Protection Agency.
The project included a flood management assessment to identify flood risk issues, a stream stability assessment for the streams in the watershed, and a water quality assessment. Each of the assessments were managed using GIS, and a custom GIS based watershed runoff model was developed to characterize pollutant loading and runoff volume for the watershed. The model was applied to identify over 50 site-specific implementation projects to reduce flooding and pollutant loading.
The comprehensive watershed study evaluated improved utilization of potential detention volume by evaluating and mapping runoff-detention volume in the 14 subbasins of the watershed. In addition to identifying a site for a large, 1,600-acre/foot regional detention reservoir, multiple other detention locations were modeled, including 29 existing ponds, 45 parking lots, and two public parks. The existing outfall structures of the ponds were evaluated and recommended for feasible retrofitting necessary to increase storage. Ponds were evaluated for necessary grading or dredging. The parking lots identified within watershed were appraised for stormwater BMPs, such as bioretention cells, rain gardens, and underground vaults, which would allow stormwater to be captured and naturally filtered into the ground. The two parks were assessed for potential use in installing BMPs, such as bioretention cells, stormwater detention basins, ponds and stormwater wetlands.
This first-of-its-kind watershed study for the county also included additional pro-active outreach to foster full public participation and education. Such communication is critical to help identify and understand the water quality issues within the local communities. Outreach included three open houses, a project Internet website, a public survey and questionnaire, and news releases to local newspapers and via direct mail.
The resulting comprehensive watershed study resulted in the development of a prioritized capital improvements program for the watershed for flood risk management, stream stability, and water quality improvements.