Friday March 31, 2023
San Francisco Estuary Magazine —
Rich Johnson steps through an inconspicuous gate between two backyards not far from the downtown San Mateo Caltrain station and points down a steep, overgrown streambank to a piece of PVC piping, barely visible beneath the tumbling water. “That’s our furthest downstream PIT array,” says Johnson, an aquatic biologist with the San Francisco Public Utilities Commission (SFPUC). The Passive Integrated Transponder array is one of four stations along San Mateo Creek that capture signals from tagged steelhead as they migrate up and down the creek.
More than a month after a series of atmospheric rivers deluged the Bay Area in January, San Mateo Creek is still running high, fed by unusually large releases from Crystal Springs Reservoir. The high flows have prevented Johnson and his team from replacing damaged equipment, and delayed their annual fish spawning survey. Nevertheless, says Johnson, “I think there have probably been adults coming upstream” from the Bay. The return of steelhead to the creek is recent, and a testament to the power of freshwater flows to restore native fish populations.
The creek, which descends alongside several roads through affluent Hillsborough before mostly vanishing beneath the streets and buildings of urban San Mateo, is little known to most local residents. Unlike some other Bay Area creeks, no “Friends of” group picks up trash from the channel or pulls invasive plants from its banks. Few of its neighbors have an inkling of the minor miracle occurring under their noses.