Join us to learn about our First Flush program, the 2025 water quality results, and the historical data trends!
First Flush is an annual community science program that looks at water quality during the first major rainstorm of the year. This early storm is important because it washes pollutants that have accumulated on roads, rooftops, and other impervious surfaces during the dry season into creeks, storm drains, and ultimately the ocean. Sampling during this time provides insight into how land-based activities affect coastal water quality under conditions when impacts are often most severe.
The program relies on volunteers to collect water samples from stormwater outfalls, creeks, and creek mouths throughout the region. First Flush is conducted across neighboring counties as part of a coordinated program managed by the Monterey Bay National Marine Sanctuary (MBNMS). In San Mateo County, the San Mateo Resource Conservation District (RCD) coordinates local monitoring efforts as part of this larger, multi-county program. Since First Flush began in San Mateo County in 2003, it has helped build a long-term record that supports water quality protection, public education, and targeted follow-up investigations.
In this webinar, we we will share the results from our First Flush event in 2025 as well as historical trends!First Flush 2025 Results Webinar:Thursday June 25th, 2026 6:30 – 7:30 pmhttps://www.eventbrite.com/e/first-flush-2025-results-webinar-tickets-1991126180004?aff=oddtdtcreator
Grace Allen, Water Quality Technician, San Mateo Resource Conservation District
Office: 650.712.7765 x 110
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