The benefits of creating a fresh-water lagoon in the Russian River at Jenner for the survival of juvenile steelhead outweigh the negatives, such as the possibility of worsening water quality, Sonoma County officials decided Tuesday.
The Board of Supervisors, which faced a violation of the federal Endangered Species Act if it did not take action, approved the final environmental report on the Sonoma County Water Agency's project.
"The urgency is high that we do this today," even though the board would have preferred the discretion to do more research, Supervisor Shirlee Zane said. "But the benefits outweigh the effects of this project."
The water agency has been ordered by the National Marine Fisheries Service to manage the Russian River at Jenner to create a fresh-water lagoon during the summer to allow juvenile steelhead, a threatened species, to acclimate before going out to sea.
To meet the order, the water agency has developed a method to let the water back up behind the sand bar when the river mouth is closed.
Instead of digging a ditch to the ocean to let the river out, the water agency lets the water rise to a depth that is just below flooding low-lying buildings in Jenner and then digs a broad, shallow northwesterly outlet to the sea.
That creates is a lagoon that is more fresh water than salt water for a longer period of time for the steelhead.
Studies on similar California estuaries, such as Carmel River, Scott Creek and the Pescadero Marsh, indicate there are substantial benefits of a fresh-water lagoon for steelhead, according to federal biologists.
The federal agency also has ordered the water agency to lower flows in the Russian River to protect chinook, which are also threatened, and to create habitat in Dry Creek for coho salmon, which are endangered.
"It is a moral imperative," said Dick Butler, a regional supervisor for the National Marine Fisheries Service. "If we continue with the status quo, we will endanger the steelhead, coho and chinook salmon."