Every summer, pollutants land on dry streets in coastal Monterey County and every winter they wash away with the rain. Examining water samples collected before and during that first rain allows scientists to see what kind of pollutants are entering the sea. But collecting those samples takes a crew of volunteers.

The public is invited to take part in First Flush, an annual water monitoring event in Monterey County that takes place before and during the first significant rainfall of the season.

Volunteers will gather rainwater samples so scientists can identify where urban pollutant concentrations are highest, but they must live in Monterey County and get to their assigned sites within 15 minutes of a call that the First Flush is underway.

“We’d like volunteers to understand that they will be outside in the rain — it’s a lot of fun but takes some dedication,” said Katie Siegler with the California Marine Sanctuary Foundation.

First Flush is an annual community science event organized by CMSF and the Monterey Bay National Marine Sanctuary, in partnership with the Monterey Regional Storm Water Management Program. The sites are in Monterey, Seaside, Salinas, Pacific Grove and Carmel.

“We’d like volunteers to understand that they will be outside in the rain — it’s a lot of fun but takes some dedication.” Katie Siegler, California Marine Sanctuary Foundation

Participation involves three events — training, taking a dry day sample and taking a second sample during the first rain.

Training takes place Wednesday, Sept. 24, from 6-7 p.m. in person at the MBNMS office at Heritage Harbor, 99 Pacific St., building 455, or online Thursday, Sept. 25, at 5:30 p.m. Volunteers will be trained on how to collect water samples and test for nutrients, metals, bacteria and sediments, while also taking field measurements such as temperature, pH, conductivity, and transparency. All sampling equipment and data sheets are provided, except rain gear.

Volunteers will be assigned their locations by email prior to the Dry Run event, which will take place Sept. 27 at 10 a.m. They get familiar with their sites, practice protocols and collect baseline data on dry-weather water flows.

Then, volunteers watch the weather. They receive a call that the First Flush is underway and must be able to reach their site within 15 minutes.

Volunteers must register online. For more information, contact CMSF’s Katie Siegler via email.

Ruth Dusseault is an investigative reporter and multimedia journalist focused on environment and energy. Her position is supported by the California local news fellowship, a statewide initiative spearheaded by UC Berkeley aimed at supporting local news platforms. While a student at UC Berkeley’s Graduate School of Journalism (c’23), Ruth developed stories about the social and environmental circumstances of contaminated watersheds around the Great Lakes, Mississippi River and Florida’s Lake Okeechobee. Her thesis explored rights of nature laws in small rural communities. She is a former assistant professor and artist in residence at Georgia Tech’s School of Architecture, and uses photography, film and digital storytelling to report on the engineered systems that undergird modern life.