This flood control structure, located on Marsh Creek between Brentwood and Oakley, is a barrier to migrating salmon. A consortium of agencies is working together to find a way to modify it, which would give the fish three times the spawning ground they can currently reach.

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There might be some good news in the year ahead for salmon: plans are being considered to give them access to more spawning territory in Marsh Creek. Eventually, they might swim right through Brentwood.

The Friends of Marsh Creek Watershed have made it one of their top priorities to remove a six-foot-tall flood control barrier located on the creek between Brentwood and Oakley. The project will be discussed at the Friends' January meeting in Brentwood. Steve Rothert from American Rivers and Rich Walkling from the Natural Heritage Institute will detail the project and offer ways locals can get involved.

Marsh Creek flows 30 miles from the headwaters of Mt. Diablo through Brentwood and Oakley to the western Delta at Big Break. The creek supports a population of fall-run Central Valley Chinook salmon, who swim every year from the Pacific Ocean to lay their eggs in Marsh Creek.

Their journey up Marsh Creek is cut short, however, because a six-foot tall concrete structure located about four miles from the creek's mouth prevents them from reaching several miles of habitat in lower Marsh Creek and its tributaries. This structure, located next to the Brentwood wastewater treatment plant, is a barrier to migrating fish, even when the creek has plenty of water in it. In November and December of 2004, the Friends of Marsh Creek Watershed citizen salmon monitoring program observed as many as 45 salmon at a time congregating immediately below the barrier.

The structure was built by the Natural Resources Conservation Service (NRCS) and the Contra Costa Flood Control and Water Conservation District. A series of major floods in the 1950s compelled the Soil Conservation Service (now the NRCS) and the Flood Control District to implement a major flood control program that involved straightening Marsh Creek. When the creek was straightened, the slope of the creek became steeper. The structure was built to compensate for the increased slope.

The barrier is also known as a "grade control structure" or "drop structure." Today the barrier is owned, maintained and operated by the Flood Control District. The U.S. Geological Survey (USGS) and City of Brentwood maintain a gauge at the drop structure to measure stream flow.

A team of interested organizations and agencies has partnered to improve fish passage at the drop structure to allow salmon to swim and spawn further upstream. The Flood Control District, Natural Heritage Institute, Delta Science Center, City of Brentwood, California Department of Water Resources, American Rivers, Contra Costa County, East Bay Regional Park District, NRCS, USGS and California Coastal Conservancy are working together to conduct a study, develop engineering plans, compile environmental documentation, provide funding and obtain permits to determine the feasibility of modifying the structure to provide fish passage.

Preliminary project plans involve partially removing or modifying the structure and installing a series of low rock formations that will allow fish to ascend and descend the six-foot elevation drop. This approach would provide unhindered passage for adult and juvenile salmon, while maintaining the stability and flood capacity of the channel. This is a proven approach that has been employed in numerous barrier removal projects in California and across the nation.

A primary cause of the dramatic drop in salmon and steelhead populations in California is that they can no longer reach more than 90 percent of their historic spawning and rearing habitat. The modification of the fish barrier would provide access to approximately seven miles of lower Marsh Creek, Deer Creek, and Sand Creek, tripling the number of accessible stream miles for these fish in the watershed. It includes approximately three miles of suitable spawning gravels and cool, shaded water downstream of and in the Cowell Ranch property (recently acquired by California State Parks). The fact that suitable, yet currently inaccessible, spawning habitat exists in a newly created public park makes this project all the more desirable.

The Friends of Marsh Creek Watershed Meeting will be held Thursday, Jan. 13, from 6 to 8 p.m. in the City of Brentwood Technology Center, 101 Sand Creek Rd., in Brentwood.

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