Clean Water Services advances major stormwater standards overhaul ahead of NPDES deadline

Clean Water Services advances major stormwater standards overhaul ahead of NPDES deadlineThe Oregon-based utility is finalizing new design and construction requirements that mandate green infrastructure and stricter runoff treatment to comply with its watershed-based permit by November 1.

CWS is updating its standards to align with a watershed-based NPDES permit issued by the Oregon Department of Environmental Quality.

The proposed rules require new and redevelopment projects to prioritize green infrastructure over hardscape controls and treat 80% of average annual runoff.

A formal public draft will be published in September, with a final board hearing scheduled for October 13, 2026.

Projects with land use applications submitted prior to the November 1 deadline will be permitted to proceed under existing standards.

Clean Water Services (CWS) in Washington County, Oregon, is nearing the final stages of a comprehensive update to its stormwater design and construction standards, driven by a November 1, 2026, regulatory deadline. During an August 25 board meeting, CWS Development and Permitting Manager Elle Allen outlined the mandatory changes required to comply with the utility's watershed-based National Pollutant Discharge Elimination System (NPDES) permit, issued by the Oregon Department of Environmental Quality. The revised standards represent a significant shift in local stormwater management. Key regulatory updates include a new standard requiring infiltration for new and redevelopment projects, supported by a numerical stormwater retention requirement and a correlating design storm. Furthermore, the updated water quality design storm will require developers to treat a depth of 80% of the average annual runoff. "We must also include language that explicitly prioritizes green infrastructure before hardscape controls," Allen told the board. The framework will also introduce a technical infeasibility and site constraints evaluation to help designers navigate the hierarchy of stormwater management requirements on a given site. To address concerns from the development community, CWS has established a vesting process. Projects that have already submitted a land use application to either Washington County or a jurisdictional city before November 1 will be allowed to proceed under the current standards. The utility has engaged in robust stakeholder outreach since December 2025, coordinating with partner cities, the Home Builders Association, the Tualatin Riverkeepers, and local design engineers. Recent adjustments to the draft standards include added flexibility for accessibility and trail improvement projects, as well as new language to streamline projects that trigger both federal and local stormwater standards. The CWS Board of Directors is scheduled to hold a public hearing on the final proposed revisions on October 13, ahead of the November 1 implementation deadline.