Salmon flourish at creek

Vacaville Reporter - January 21, 2007
By Erin Pursell

Salmon flourish at creek
Vacaville Reporter – 1/22/07
By Erin Pursell, staff writer

It appears that - even during dry years - Putah Creek is home to a self-sustaining salmon run.

At least 12 to 18 Chinook found their way home there to spawn, thanks in part to the December release of water from Lake Berryessa, according to a report recently released by UC Davis biologists regarding the spawning season.

"It means that those pulse flows are like a lifeline during dry years," said Rich Marovich, streamkeeper for the Lower Putah Creek Coordinating Committee.

The strong flows - more than 50 cubic feet of water per second were released from the Putah Diversion Dam for five days - help salmon to navigate around beaver damns and other obstructions, and were essential after dry fall weather resulted in little runoff.

"We learned the pulse flow is a reliable source of water during dry years," Marovich explained.

It's critical that the flow is available during the five-week run, which occurs between Dec. 1 and the first week of January.

Because U.C. Davis biologists found no live or dead salmon during their recent survey, the encouraging estimates are based on the assumption the there was one female and one to two males for each nest that was found, according to the report.

The salmon nests - which appeared as if they had been created around Christmas-time - were easy to identify, the UC Davis report continues.

They consist of large, cleared areas of gravel with at least one depression in the middle, located at or near the tail end of pools. This is identical to nests documented in previous years.

While the numbers aren't what they'd hoped for, the fact that any fish made their way up from the Sacramento Delta through Rio Vista, along a waterway called the Toe Drain, is encouraging, Marovich said.

"I think the interesting thing is that we've had a year with almost no runoff," he said regarding the species' ability to migrate for procreation.

This is the first year that salmon spawned during the record 2003 run would return to do their own spawning.

Salmon also rely heavily on rain runoff into streams because it gives the water a certain flavor that helps them find their way back into native streams.

There have been ongoing restoration efforts in the creeks, which will need to continue, Marovich said.

Biologists found no nests in the creeks restoration sites. One possible reason for this, the report offered, is that the salmon appeared to be "quite choosey" about water depth.

Between now and the next salmon run, debris need to be cleared from rock weirs - rows of rocks that retain gravel - to avoid excessive depths for spawning, Marovich said.

"It's kind of annual maintenance," he explained.

Biologists will look for juvenile salmon this spring, as evidence of successful spawning. #
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