State Water Board adopts statewide cost-reporting policy for municipal stormwater permits; reporting to begin FY 2026-27

The State Water Resources Control Board on Jan. 22 adopted a Water Quality Control Policy to standardize cost reporting for municipal stormwater (MS4) permits, instituting statewide categories and a data portal for machine-readable cost reporting. The board approved the policy and associated resolution unanimously after a multiyear development process that included a 6-month beta test.

Amanda McGee, senior engineering geologist in the Division of Water Quality, summarized the policy’s goals: improve consistency and transparency of stormwater implementation costs, help estimate costs for new permit requirements, and provide standardized data to inform funding and permit decisions. McGee said the policy responds to a 2018 California State Auditor recommendation and was developed with stakeholder input in multiple public comment rounds.

Key components and implementation timeline - A statewide cost reporting framework with categories and subcategories for permit elements (with simplified reporting for traditional Phase 2 MS4s). Several subcategories were clarified or removed after comment. The policy clarifies that structural best management practice (BMP) cost reporting applies only to public permittee-owned projects and no longer requires BMP surface…