American Rivers Releases Guide To Integrate Green Infrastructure Into Stormwater Permits


Stormwater flooding in Washington, DC

Stormwater flooding in Washington, DC | Lynette Batt

Most of us don’t think about “urban stormwater” or “polluted runoff” until we notice flooding from a recent storm covering our roads and parking lots, as shown here.

But polluted stormwater runoff from our rooftops, roads and shopping centers pollutes our streams and rivers across the country and is the leading pollution source in places like the Puget Sound.

How is polluted runoff managed?

Permitting is a critical tool under the Clean Water Act by which polluted runoff can be managed and reduced. Beginning in 1987, the Clean Water Act has required that municipal storm sewer systems and other major sources of stormwater obtain discharge permits to limit the harmful effects of polluted runoff on rivers and streams.

These permits are authorized under the National Pollutant Discharge Elimination System (NPDES), and are known as MS4 NPDES permits. These permits contain a suite of minimum requirements that dischargers must meet, including preventing erosion and sediment flows from construction sites and minimizing runoff when land is developed for commercial, residential, or industrial use. However, despite decades of stormwater permitting, polluted stormwater runoff remains one of the most significant problems for our nation’s waters and communities.

Why have we seen little success in reducing polluted runoff?

Polluted runoff remains a significant source of pollution largely because the permits that regulate it are based on a poorly defined and highly discretionary standard that calls for measures that reduce stormwater “to the maximum extent practicable.” Most permits are built around this narrative standard, and do not impose clearly articulate, numerically expressed performance requirements or limits on stormwater discharges.  This often results in approaches that fail to achieve clean water.

Technologies such as gutters, culverts, ditches, and large detention basins that collect huge volumes of stormwater and convey it rapidly, with little pollutant removal, to nearby streams, rivers and lakes are often the favored approaches.

However, as the National Research Council has documented, a better approach is often to keep rainfall where it falls, before it has a chance to accumulate, pick up pollutants and flow into the closest storm drain.  In other words, if we’re going to really clean up our waters, we need MS4 NPDES permits that foster the use of green infrastructure to manage stormwater.

To help move us toward the day when all stormwater permits more fully protect our waters and communities, we’ve researched and released a guide to integrating green infrastructure into these MS4 permits. This guide:

  • Evaluates some of the best examples of stormwater permits from around the country, and provides the regulatory language that they use to drive property developers toward using green infrastructure practices, and
  •  Provides examples to watershed advocates of comment letters that have helped state agencies shape this critically important revolution in stormwater permits. 

At American Rivers, we’re advocating for overall improvements to the Clean Water Act’s stormwater regulations,  but our goal here is to provide easy-to-use, practical guides for stormwater advocates and agencies to improve permits now. This guide is intended to do just that – and to evolve as permits themselves evolve.  If we’ve missed a good one, or as a new permit emerges, we hope you’ll tell us about it.