All drains may eventually lead to the ocean, but what happens when stormwater moves for the first time in a long while? During the first rain of fall, it takes a committed volunteer force to monitor those murky waters to get an answer. 

The San Mateo Resource Conservation District is looking for volunteers to help check these outfall points with its biggest volunteer and water sampling event of the year, “First Flush,” which takes place when the first significant rain of the season washes accumulated pollutants from land into creeks, storm drains, and the ocean.

This program, funded by Sewer Authority Mid-Coastside and the San Mateo County Harbor District, monitors water flow to provide information about a wide variety of pollutants. Volunteers track bacteria, nutrients, metals and acidity levels. Managed by the Monterey Bay National Marine Sanctuary Foundation, the RCD is the event’s local host.

There will be a training next week, hosted by Noah Katz, water quality program coordinator. 

This effort also serves as an educational opportunity to inform the community on pollution and what can be done about it, no matter a volunteer’s level of expertise.

Katz said there will be 15 sample sites, split between five groups from Montara to Half Moon Bay. Collected samples will be tested for metals and nutrients at Monterey Bay Analytical Services. Bacteria samples will go to the San Mateo County Public Health lab. The results would be published several months after the rainfall, most likely in December. 

“I’m interested in citizen science, and I think everyone should have some interest in looking into their own waterways and environment,” Katz said. “It’s a really great way to know your community and learn.”

Brittani Bohlke, the water quality program manager, said the RCD wants as many volunteers as possible of any age because there are too many places to cover when the first rains hit. 

“It’s such a short amount of time that we have to capture this first pulse of pollution,” Bohlke said. “So that’s why it’s a volunteer event, because we can’t capture that at multiple locations with just a couple staff members.”

Contact Katz at and visit for information. Training takes place at 6:30 p.m. Sept. 10 at 80 Stone Pine Road, Suite 100 in Half Moon Bay.

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