Planning for Holistic, Watershed-Based Stormwater Management in Johnson County, Kansas

In 2015, the Johnson County Stormwater Management Program created a strategic plan that focused on meeting evolving stormwater management needs of our stakeholders. The strategic plan identified main objectives below for the Program moving forward- 1.Watershed Based Organization: Modify organizational structure to allow for comprehensive watershed-based stormwater improvement plans. 2.Water Quality: Develop funding criteria for water quality improvement projects. 3.Flood Damage Reduction: Develop new funding criteria and procedures for flood damage reduction projects. 4.System Management: Develop a comprehensive asset inventory of stormwater systems and develop funding criteria for system replacement projects. The updated direction of the Program encompasses much more than just addressing flooding. Water quality, stream erosion, and storm sewer management are all a part of the Program moving into the future. Solutions that manage rain where it falls and include natural elements are more widely implemented. Holistic, watershed-based solutions are replacing single projects and proactive planning efforts are replacing the former reactive nature of stormwater management. The watershed master plans set the stage for Johnson County to manage stormwater in this multi-faceted way. Background Johnson County, Kansas is in the south-western portion of the Kansas City metropolitan area and is the most populous county in Kansas with a population of approximately 610,000. The population has increased rapidly from approximately 60,000 in 1950 with a median increase of 26 percent every ten years. Naturally, rapid population growth results in an increased development and impervious surfaces causing challenges for stormwater management. Adding to these challenges, there are 20 cities in the County, ranging in population from approximately 200 to 197,000 residents resulting in varied abilities for each city to address stormwater challenges alone The Johnson County Stormwater Management Program was established in 1990 when the Board of County Commissioners adopted State of Kansas legislation enabling the County to levy a retail sales tax of 1/10th of one percent for the purposes of funding stormwater management and flood damage reduction improvements. The Program's purpose is to provide financial, technical, and planning support services for municipalities within the County for stormwater management. In 2002, the Program created its first business plan that expanded the focus areas to include assistance to the cities for NPDES MS4 permit requirements and allow for funding of research and development projects. Since then, the focus of stormwater management nationally has evolved to include more than just flooding and regulatory concerns. Stream erosion and hydromodification of urban streams are a direct result of increased runoff and contributes to water quality impairments as well as threatening public infrastructure as well as stream-side private property. Storm sewer infrastructure is failing resulting in municipal stormwater funds being allocated to emergency repairs leaving less for flood reduction projects. Additionally, it was becoming apparent that in order to effectively address stormwater challenges, solutions must be considered at the watershed scale as opposed to limited to jurisdictional boundaries. Watershed Master Plan Approach The Program embarked on a Watershed Master Planning process in 2019. Realizing this level of planning is beyond the scope of any one city the SMP led the planning effort with input and review throughout the process. The ultimate watershed master plan goal is to identify the various risks within the watersheds, prioritize the risks and develop an approach and solutions to address a broad range of watershed needs. The planning process is organized into three primary parts with the ultimate goal of developing five-year capital improvement plans for each Watershed Organization to prioritize actions that provide the highest benefit. To achieve that goal, a two-phase planning process will be used to ensure the county's highest needs are resolved as expeditiously as possible. The Phase 1 plan's primary objective is to identify the highest risks and needs within each Watershed Organization's boundaries, align those risks with the greatest opportunities in the watersheds, and use that to inform the watershed organizations where focus should be placed in Phase 2. The Phase 2 plan will target the identified priority areas for detailed analysis, complete with specific cost/benefit scoring, that will build the first five-year CIP for each Watershed Organization. There will likely be more project needs in each watershed than can be funded in a five-year period; therefore, the Phase 1 plan serves as a filtering process to identify those highest risk areas for consideration first. The Phase 1 plan includes the following key elements: -Geomorphic evaluations using LiDAR technology to identify areas of stream instability and degradation, as well as the nature of the issues to aid in development of potential solutions -Identifying known flooding areas based on modeled floodplain data, input from cities and citizen surveys, and from proposed flood reduction projects -Synthesizing existing water quality data to identify opportunities for improving water quality and watershed health -Assessing the degree of stream hydromodification and determining runoff volume control strategies needed to help restore healthy stream flows -Identifying critical watershed opportunities and constraints as they affect the feasibility of potential projects, policies, and action plans -Recommending watershed-based actions that comprehensively target the most critical flooding, stream stability, and water quality issues in the watershed The plans will serve as roadmaps for the watershed organizations for the next 20 plus years of stormwater management in Johnson County as we continue to tackle flooding, water quality, and stream erosion challenges. This presentation will cover the results of the Phase 1 Watershed Master Plans as well as the beginning of Phase 2 studies.