Comprehensive Updates to Stormwater Design and Management Standards for the Kansas City Metropolitan Region

The Center for Watershed Protection (CWP) was part of a team convened by the Kansas City Metro Chapter of the American Public Works Association and the Mid-America Regional Council to comprehensively update stormwater design and management standards for the Kansas City metropolitan.

The Kansas City region covers a nine-county area which includes 119 communities in Missouri and Kansas. Local governments in the region adopt stormwater design standards maintained by the Kansas City Metro Chapter of the American Public Works Association (APWA) to govern stormwater quantity management, while the 2003 APWA/Mid-America Regional Council (MARC)’s best management practice manual has been the standard for stormwater quality management. While both manuals cross-reference each other, no true integration existed and the last updates were made in 2011 and 2012. Over the 20+ years since these manuals were published, major advances in stormwater management have been made.

Local leaders recognized the need to integrate both water quantity and quality manuals to address the issues facing the region, including urban flash flooding, rapid and severe stream erosion from poor stormwater management, and water quality issues, as well as ineffective and inconsistent stormwater designs. As part of a consultant team with Burns and McDonnell, Black & Veatch, and Vireo, CWP worked with MARC to comprehensively update stormwater standards for the Kansas City region. The final APWA Regional Stormwater Standards combines and supersedes the previous versions of the APWA and MARC/AWPA manuals, combining water quality and quantity management into one coherent system.

The new manual emphasizes a volume-based approach to address water quality, prioritizing preservation and restoration of natural areas and waterways, and requiring that precipitation from smaller rain events be held on site so it can infiltrate or evapotranspire instead of running off immediately. Other key elements of this manual include:

Modern precipitation modeling: rainfall standards reference NOAA’s Atlas 14, with hydrographs based on actual storm data rather than outdated approximations
Redevelopment considerations: Less stringent standards that will still create tangible improvements for water quality and flooding in already developed areas
Detailed design guidance: design specifications that ensure stormwater management practices will be constructed and function as intended
Better landscaping criteria: vegetation designs based on local experience and intended to facilitate long term growth and performance

The project took place over a two-year period and included a robust stakeholder engagement effort that included more than 240 different individuals and at least 50 meetings and workshops resulting in over 1,400 stakeholder hours. CWP participated in all aspects of this collaborative project, meeting often with local experts and stakeholders to discuss key issues and work out consensus-based solutions. CWP’s main role was to share our knowledge of stormwater science and regulatory approaches from across the country to help the project team create a truly state-of-the-science manual.

The Kansas City Metro Chapter of the APWA approved the new stormwater manual at the end of 2025. MARC is working to advance the adoption process with local governments and also plans to provide training for developers, designers, municipal staff, construction contractors, and maintenance contractors on implementation of the new standards. The updated design manual marks a monumental step forward in the Kansas City region towards the desired outcomes of more sustainable, cost-effective, and adaptive stormwater designs that reduce flooding, improve water quality, and steward the region’s natural resources.

For more information about this project, contact Greg Hoffmann at gph@cwp.org.