Opening up the historic spawning grounds within the Pescadero watershed

Photo Cred: San Mateo RCD

Photo Cred: San Mateo RCD

“From saving redwoods almost a century ago to saving salmon and steelhead today, Memorial Park is a special place in the history of conservation.” –Marlene Finley, San Mateo County Parks Director

There are 20 parks and over 190 miles of local and regional trails in the San Mateo County Park system we all know and love today. But it all started with one: Memorial County Park, protected and dedicated in 1924, and named in honor of San Mateo County residents who died in the line of duty during World War I.

It was a prescient move to save these old-growth redwoods from the lumber mill and preserve them as a park. Memorial County Park has been a popular spot for hiking and camping for nearly a century, offering a peaceful respite from the hustle and bustle of daily life. Now, efforts are focused on saving endangered and threatened species that have long called the park, and the creeks within it, home.

Pescadero Creek, with its sources in the Santa Cruz Mountains, flows through Memorial Park before draining an 80 square mile watershed into Pescadero Marsh and the Pacific Ocean. Historically, there was an abundance of coho salmon and steelhead trout in Pescadero Creek; but today, coho salmon are critically endangered, and while it is one of the largest remaining runs of steelhead within the San Francisco Bay region, this fish is threatened as well.

A number of factors have contributed to the species decline including overfishing and habitat destruction, but locally, one important factor played a role: fish passage barriers along Pescadero Creek. The two remaining barriers, remnants of the Depression-era Works Progress Administration, came in the form of a dam built to create a swimming hole and a concrete span providing access to a popular campground. These were partial barriers, in that they were only a barrier under certain flows. The water could be too fast or too low.

While filling recreational needs in their day, the barriers prevented juvenile anadromous fish, which spend the first year of their life in the creek, from moving up and downstream to take advantage of pools, shade, cover and food sources. The barriers also made it difficult for the juvenile fish to complete their migration to the sea, where they spend most of their life before returning to fresh water to spawn. Steelhead trout have great swimming and leaping capabilities, so they are more likely to be found upstream of these partial barriers. The coho salmon is not as strong, which makes these barriers more challenging for the fish.

Eliminating the last two barriers to fish passage along Pescadero Creek had long been a priority of County Parks and the fisheries agencies. In partnering with the San Mateo County Resource Conservation District (RCD), plans and designs were finally put into action, culminating in a quick tear down of the barriers.

Resource Conservation Districts across California serve as local hubs for conservation, connecting people with the technical, financial and educational assistance they need to conserve and manage natural resources.

The natural creek bed was restored where the dam had previously been. The vehicle ford was replaced with v-notched weirs and pre-cast arched culverts that allow freer passage for fish at a wider range of water levels, especially for juveniles during low flows. Construction had to occur over a very short timeframe due to the presence of the endangered marbled murrelet nests in nearby old growth redwoods and the need to keep the park open during popular summer months.  But they did it, and to positive results.

“We are ecstatic to have opened up access to over 62 miles of some of the best habitat in the watershed for the critically endangered coho salmon that is on the verge of extinction locally”, said Kellyx Nelson, Executive Director of the San Mateo County Resource Conservation District.

After just one winter, immediate benefits include a free flowing stream with unimpeded fish passage plus the transference of stored sediment, gravel and cobble to downstream areas, creating a more complex habitat for the fish.

This is a big success and one that resulted from a collaborative multi-agency partnership, especially between County Parks and RCD. When people work together, they can accomplish amazing things. This includes setting aside land as a park for future generations to enjoy as well as safeguarding the waterways within it for the benefit of threatened and endangered species.

The next time you visit Memorial County Park, think about the amazing journey of the anadromous fish to and from the sea, and the role humans can play in either hindering or aiding it.

The San Mateo County Parks Foundation provided financial support for this stewardship project.

You can watch a time lapse video of the dam demolition here.






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