In a recent meeting held by the State Water Resources Control Board on February 6, 2025, discussions centered around the Urban Stormwater Infiltration Policy, highlighting its potential impact on California's water supply and quality. The board emphasized the importance of ensuring that stormwater management practices benefit the majority of residents while addressing the challenges of connecting drinking water suppliers with stormwater managers.

One of the key points raised was the need for effective pretreatment of stormwater to prevent contaminants, such as microplastics and trash, from entering groundwater systems. The board acknowledged ongoing studies aimed at understanding the effects of these pollutants and confirmed that capturing trash before infiltration is a minimum requirement across all systems. This focus on water quality is crucial, as it directly affects the safety of drinking water supplies.

The meeting also addressed ownership of water captured through infiltration. Once stormwater is infiltrated, it becomes part of the groundwater basin, classified as "water of the state." This raises questions about the responsibilities of local agencies and the financial implications for ratepayers. However, board members clarified that the policy does not mandate additional infrastructure development for agencies already managing their water sources effectively.

Furthermore, the board discussed the alignment of surface water quality objectives with drinking water standards. While the vadose zone can naturally filter contaminants, the board indicated that they are unlikely to require pretreatment to meet drinking water standards, focusing instead on maintaining surface water quality.

The meeting concluded with a brief overview of successful infiltration policies in other states, such as Washington and Oregon, which have reportedly provided clarity and benefits for management agencies. The board plans to incorporate insights from these states into California's policy framework.

As California continues to grapple with water supply challenges, the discussions from this meeting underscore the importance of thoughtful stormwater management practices that prioritize both water quality and community needs. The board's ongoing efforts aim to create a sustainable approach to urban stormwater infiltration that serves the interests of all Californians.