Municipal stormwater programs face many challenges in managing polluted runoff. Today, there are 7,550 communities covered by municipal separate storm sewer system (MS4) permits, representing more than 80% of the country’s population but only 4% of land area, according to the National Municipal Stormwater Alliance (NMSA).

The US EPA’s stormwater rules were issued nearly three decades ago, yet as recently as 2015, the Water Environment Federation found that while practices have improved, stormwater is the only growing source of water pollution in many watersheds throughout the US.

“Growing source? Despite all our efforts? Unfortunately, yes,” writes Paul Davis, National Stormwater Center Instructor, in the forward of a new report from NMSA. “We’re not yet keeping contaminants out of stormwater, and we’re not yet managing drainage so that, as much as possible, rain stays where it falls. The result is pollution that’s putting urban populations at risk, threatening public water supplies, and diminishing aquatic life.”

How are we falling short? In its inaugural State of Stormwater Report, the NMSA provides an overview of municipal stormwater programs across the US, detailing the challenges and opportunities communities face in managing polluted runoff.

The report was developed by MS4 program managers and gives a snapshot of the challenges facing MS4 programs. The top six challenges are:

• Program funding, and in many cases staffing; many MS4 communities do not have a designated funding source and face significant challenges developing one.
• MS4s are fostering awareness of and public engagement in stormwater solutions, but more work is needed to gain public and elected official support.
• MS4s face evolving regulatory requirements. Many MS4 program managers cite the need for additional program support and guidance, especially as communities implement new technologies and techniques — such as green infrastructure — for post-construction stormwater management.
• Many MS4 program managers characterize their water quality as static to improving. However, they cite challenges in measuring program effectiveness in receiving water quality due to a lack of monitoring data and the obscuring influence of other nonpoint pollution sources. While MS4s are making progress improving the health of the nation’s waterways, climate change and urbanization threaten progress in some regions.
• Additional research is needed on urban stormwater management practices to better inform decisions about their use and overall life cycle costs, including design, construction, and long-term maintenance.
• To make significant progress improving water quality, MS4s recognize the need for watershed-wide collaborations and source control. Many state leaders are promoting integrated solutions for MS4s that address flooding, combined sewer overflows, and other nonpoint pollution sources, such as unregulated agriculture.

“MS4s are tackling one of the most difficult water resource challenges today — managing stormwater and revitalizing urban waters,” said NMSA Chair Scott Taylor. “Each state is attacking issues in somewhat different ways. This report takes a look at that for the first time, providing information critical to moving the needle on clean water.”