Efforts to bring coho salmon back from the brink of extinction in the Russian River watershed finally may be working as researchers report a significant increase in the number of fish in the river, Salmon Creek and their tributaries.

"This year there were large numbers of fish where we never saw them before," said Brittany Heck of the Gold Ridge Conservation District. "We did snorkeling in Salmon Creek and in some areas where we (once) saw 50, there were 250."

The numbers are encouraging, but the fate of the coho, a beautiful silver fish with a hologram of green and red colors on its flank, is still far from certain off the California coast and in state waterways.

"We are moving in the right direction, we are definitely seeing signs of recovery, but we are a long way from the end goal," said Ben White, manager of the coho breeding program at the Warm Springs hatchery northwest of Healdsburg.

The effort to save the coho, now a decade old, comes with a price tag in the millions of dollars to breed fish at the hatchery, create habitat in streams and creeks, and provide erosion control on more than 200 miles of rural roads.

The Sonoma County Water Agency alone has spend almost $2 million studying and drawing plans to create habitat on Dry Creek to help coho survive the high flows necessary from Lake Sonoma to provide a domestic water supply for 600,000 Sonoma and Marin residents.

The creek work itself is expected to cost $6 million to $7 million a mile to put in rock and timber to create pools and eddies for the coho.

Dave Manning, a senior environmental specialist for the water agency, said the outlay is necessary to maintain the fishery and still be able to supply water and other services.

"The amount of money spent is substantial, but it doesn't approach the amount of money that could be spent" on other options, Manning said.

The coho salmon is on the federal endangered species list in California, with as few as three of the wild fish seen returning to spawn in the Russian River in 2004.

This year, with the spawning run just getting under way, 77 coho have been photographed swimming through the water agency fish ladders near Forestville, more than twice the number seen at this time last year.

The goal, however, is to have 6,000 fish returning to spawn each year, White said.

"The couple hundred we will see is a long way from our goal, but it is also more fish than we have seen in the last 10 years. It it is a step in the right direction," he said.

In surveys by University of California Cooperative Extension researchers equipped wit snorkels, 5,375 juvenile coho were found in the Russian River and its tributaries between May and September. In comparison, there were 715 last year and 637 in the five prior years.

In Salmon Creek in far western Sonoma County and its tributaries, 880 juvenile fish were seen this year, double the number of last year.

The breeding program, run by the Army Corps of Engineers at the Don Clausen Hatchery, began in 2001 and now is headquartered in a sprawling red shed at the base of Warm Springs Dam.

Biologists on Wednesday were sorting through 600 adult coho raised in tanks, using ultrasound to determine whether females were ready for breeding and squeezing the flanks of males to gauge if they were prepared to fertilize the eggs.

The coho have been raised in captivity and will be selected genetically for breeding to reduce inbreeding.

The offspring, which are tagged for identification, will be released next year.

This year biologists released 175,000 juvenile salmon from previous breeding efforts into the Russian River, Salmon Creek and dozens of tributaries.

The program, which costs about $700,000 a year, is supplemented by work done on coho habitat to enhance the survival rate of the juvenile fish, which will go to the ocean for 18 months before returning to spawn.

"It is great to have adult coho coming back, but if there is not habitat and the juvenile all die, it is not going to work in the long run," said Mariska Obedzinski of the UC Cooperative.

Over the past several years, the Sotoyome Conservation District has spent $7 million in federal funds on several projects, including erosion control on 200 miles of roads, helping grape growers create off-stream reservoirs and other alternative frost-control measures and in creek habitat restoration.

The Gold Ridge Resource Conservation District has spent about $1.5 million for studies and a pilot project to help residents and ranchers capture rainwater to replace water pumped from Salmon Creek.