Tracking steelhead in Stevens Creek Tracking steelhead in Stevens Creek (October 21, 2005)

Runs persist despite dam, other obstacles

By Jon Wiener

A century ago, steelhead trout from San Francisco Bay journeyed for miles up Stevens Creek every year, spawning in the headwaters that form in the Santa Cruz mountains.

The construction of Stevens Creek Reservoir and Dam in 1935 changed all that, and decades worth of development along the lower reaches of the creek have made steelhead spottings increasingly rare.

So it was a welcome sight to Mondy Lariz when he saw two adults and 12 or more "young of the year" two weeks ago.

"We didn't capture them to positively identify them, but I'm positive they were steelhead," said Lariz.

Lariz is the executive director of the Stevens Creek and Permanente Watershed Council and was out touring some of the sites the group uses to monitor the health of the stream and its ability to support steelhead. The council received another grant this spring to do additional monitoring work.

In 1954, the Department of Fish and Game rescued nearly 7,000 young steelhead trapped in pools while the creek was drying up around them. Today, creek watchers estimate that between 10 and 100 steelhead -- a type of rainbow trout that swims back out to the ocean after it has spawned -- make the journey up the creek each year.

The fish is protected as a threatened species, meaning that Lariz and others are not allowed to capture them to do identifications, so nobody knows how many the creek actually supports.

"We would like to know," said Melissa Moore, a biologist for the Santa Clara Valley Water District. "But because this fish is listed under the Endangered Species Act, we don't have a permit to handle it."

Steelhead are larger and more silvery in color than creek-bound trout. In recent years, the water district has begun taking steps to make their migration easier, building a fourth "fish ladder" near Central Expressway and leaving dead trees in the creek to provide habitat.

But Lariz believes the dam is still the biggest threat to the fish. Not only is it impossible to pass, but it acts like a sieve, catching sediment and releasing it constantly throughout the year, thereby choking off the steelhead's food supply.

"That doesn't sound like a big deal," said Lariz, "but our theory is that these particles settle out because the stream flow is so regulated and so low, and they bury the rocks where bugs would normally grow."

The watershed council is working with the U.S. Geological Survey on possible solutions, including putting gravel beds in parts of the creek or adding filtering mechanisms at the dam.

E-mail Jon Wiener at jwiener@mv-voice.com

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