The California State Water Resources Control Board (State Water Board) has begun its process to develop a new statewide Urban Stormwater Infiltration Policy. The goal of the proposed new policy is to establish statewide standards for stormwater infiltration to provide a consistent regulatory framework to "encourage infiltration of urban stormwater and increase local water supply resiliency, provide greater protection of stormwater quality, and develop projects with multiple benefits for communities."
The proposed policy scope includes the following components:
- Decision-making framework and support tools for assessing infiltration conditions, including potential prohibitions to protect groundwater quality.
- Minimum siting, design, operation, and maintenance requirements for new or expanded systems.
- Requirements for existing infiltration systems.
- Antidegradation analysis of the effects of stormwater infiltration on groundwater quality.
The State Water Board intends to adopt a risk-based approach to encourage implementation of urban stormwater capture and infiltration projects. During a policy scoping workshop held earlier this month, staff proposed regulation of infiltration projects through various risk tiers: (1) low risk infiltration systems (e.g., residential areas), (2) medium risk infiltration systems (e.g., commercial areas or strip malls), (3) high risk infiltration systems (e.g., industrial areas or places with existing groundwater contamination), and (4) certain prohibited cases. Staff also anticipated proposing minimum setback requirements from infiltration systems, but suggested that the State Water Board could offer flexibility based upon the circumstances.
The next step in the process for the development of the Urban Stormwater Infiltration Policy is a CEQA scoping workshop to be held on March 12, 2025, with written comments on the CEQA scoping issues accepted until March 31, 2025. From there, the State Water Board anticipates releasing a draft Urban Stormwater Infiltration Policy in late 2025 and then will hold workshops for public comments on the draft policy.
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