Dam Removal for Steelhead

by on July 01, 2007

 

 

In what ought to be a landmark action to restore steelhead trout runs in the region, two dams are slated for removal this year on Alameda Creek, which drains the Bay Area’s second-largest watershed. A third barrier will go by the end of 2007. But the removal of the dams will be mostly symbolic until a fish ladder is installed across the largest barrier—the BART weir in Fremont.

This year, the San Francisco Public Utilities Commission will demolish two out-of-service dams in Niles Canyon. Next year, the Alameda County Water District will remove an inflatable dam in Fremont.

“Removing these dams is a significant milestone, but installing a fish ladder at the BART weir is still our highest priority,” says Jeff Miller of the Alameda Creek Alliance. Since 1997, when the steelhead trout was listed as a federally threatened species, the alliance has documented adult steelhead attempting to migrate up the creek to spawn.

When an adult steelhead ventures up the lower reaches of Alameda Creek, it swims in a 12-mile-long flood control channel constructed in the 1960s by the Army Corps of Engineers. The channel’s water is too warm and too full of sediment for spawning and provides no shade, no pools for resting, and no protection for eggs and young fish. Within ten miles of the Bay, the fish reaches the impassable BART weir, a bank-to-bank graded cement slope designed to prevent channel erosion and to slow the water before it hits the piers supporting the Southern Pacific railway and BART tracks. Although a steelhead is capable of jumping up to 19 feet over natural barriers, it needs a pool to build speed. In the shallow water at the bottom of the weir, the steelhead can’t build up enough speed to overcome the obstacle.

Fortunately for the steelhead, 12 agencies are currently trying to raise the needed $8 million for construction of the fish ladder. Also, several of the agencies are pooling funds for a flow study that will determine how much water should be released from upstream dams to maintain a viable steelhead population in Alameda Creek.

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