Key Takeaways

Ecology’s proposed 2026 CSWGP contains several changes from the current CSWGP , which took effect in 2021 and expires on December 31, 2025. This alert provides a high-level overview of the proposed changes.

Background

The federal Clean Water Act (CWA) and its implementing regulations require a National Pollutant Discharge Elimination System (NPDES) permit for stormwater discharges from any construction activity disturbing one or more acre of land, or construction activity disturbing less than one acre of land and part of a common plan of development or sale that will ultimately disturb one or more acres of land. Like most states, Washington has EPA authorization to administer the NPDES program for discharges within its borders.

There are two types of NPDES permits: (1) individual permits that reflect site-specific conditions for a discharger, and (2) general NPDES permits that cover multiple discharges with similar operations and types of discharges, such as the CSWGP. Construction operators in Washington requiring a NPDES permit can seek coverage under the CSWGP in lieu of an individual NPDES permit by submitting a Notice of Intent (NOI), indicating the discharger will comply with the conditions of the CSWGP.

Significant Changes from the Current CSWGP

Discharges must not cause or contribute to a violation of surface water quality standards (Chapter 173-201A WAC), groundwater quality standards (Chapter 173-200 WAC), sediment management standards (Chapter 173-204 WAC), and human health-based criteria in the Federal water quality criteria applicable to Washington. (40 CFR Part 131.45) Discharges that are not in compliance with these standards are prohibited.

The above provision violates San Francisco by making the permitholders responsible for the overall quality of waterbodies. However, Ecology proposes to leave in—with modified language—a statement that “Ecology presumes that water quality standards are protected in the receiving water when” a permittee complies with the CSWGP.

Implications

Operators of small sites (i.e., those disturbing 1 acre or less) could see increased compliance costs. For example, the draft 2026 CSWGP permit will increase the small site compliance burden by requiring small sites to comply with weekly turbidity, transparency, and pH testing in comparison to the 2021 CSWGP permit where small sites were not subject to weekly testing. Additionally, as was the case with the current CSWGP, Ecology anticipates the 2026 CSWGP will also have a disproportionate impact on total annual compliance costs for small businesses who employ an average of ten (10) employees as compared with larger businesses with an average of 78,647 employees, notwithstanding Ecology’s purported measures to mitigate disproportionate costs such as providing extreme hardship permit fee reduction. See Small Business Economic Impact Analysis at p. 10.

On the other hand, permittees will no longer face the uncertainty and compliance burden of struggling to comply with vague and unattainable “end-result” prohibitions, making them responsible for water quality conditions that no single permittee can control.

Ecology’s draft 2026 CSWGP and associated fact sheet with additional supporting documentation is available for public comment through May 9, 2025. Operators currently engaged in construction activities, or expected to engage in construction activities in the near future, should consider submitting public comments. For more information on or assistance with the public commenting process , please contact the authors.