Hydrology Blog

This summer, the San Francisco Bay Area Network’s coho and steelhead monitoring team started a two-year project to inventory aquatic species in streams across Point Reyes National Seashore and Golden Gate National Recreation Area using environmental DNA. Environmental DNA, or eDNA, is genetic material shed by organisms in the water column. By collecting particulate samples from the water, we hope to learn if species of interest are utilizing certain streams.

The second phase of a major restoration project aimed at improving habitat for salmonids in Muir Woods National Monument is underway. The San Francisco Bay Area Network’s coho and steelhead monitoring team assisted with the restoration project by removing fish from the construction areas prior to the arrival of heavy machinery.

This has been a highly productive spawner season for the salmon in the Olema and Redwood Creek watersheds. The San Francisco Bay Area Network coho and steelhead monitoring crew spotted over 140 Chinook, coho, and steelhead redds (nests) in these creeks since November. These encouraging numbers are largely due to the heavy rainfall the Bay Area received in late fall and early winter. However, two months without significant rain has sounded some alarms for our coastal streams.

Explore the ways in which climate change will impact life at Muir Woods National Monument and people around the world with the changing availability of water.

This summer continues to be a challenge for the San Francisco Bay Area Network Fisheries Team and the aquatic life that inhabit our coastal streams. During our summer habitat monitoring, we found several drying pools in lower Redwood Creek in Golden Gate National Recreation Area. We also noted fish displaying signs of distress like rising to the surface for air. Our team is working closely with park managers and regulatory agencies to help save these young coho and steelhead.

For the first time in the Coho and Steelhead Monitoring Program’s history, the monitoring crew had to stop outmigrant coho salmon smolt trapping early due to low flows. They removed the traps from both Olema and Redwood Creeks. This is just one of many indicators showing how severe the drought is this year.

For decades, coho salmon returning to spawn in urban Pacific Northwest streams have been mysteriously dying in the aftermath of large storms. Now, after a painstaking search for answers, a team of scientists have found the culprit: a previously undescribed chemical nicknamed 6PPD-quinone. Meanwhile, scientists in California’s Central Valley noticed odd behavior and high mortality among juvenile Chinook salmon in multiple hatcheries just last winter.

This month, a project began in Muir Woods that aims to address one of the biggest threats to the survival of endangered coho salmon in Redwood Creek: the lack of good stream habitat for young fish.

The Presidio Trust, Golden Gate National Parks Conservancy, and Golden Gate National Recreation Area have worked to restore the Tennessee Hollow Watershed for over two decades. However, one key part of the watershed, where the creek connects to Crissy Marsh, remains buried under a sea of pavement and confined to a 72-inch storm drain. Next month, that will start to change.

The Redwood Creek Vegetation program hosted a One Tam BioBlitz in mid-May along Bootjack Creek in Mount Tamalpais State Park. This site was of particular interest to park managers because of its serpentine soils, which are rare within the Redwood Creek watershed, and because only limited botanical surveys have been done here in the past.