Chinook salmon, the fish on the federal threatened list that caused widespread conservation measures to be imposed in Sonoma County this past summer, are returning to the Russian River in increasing numbers.

"We have gotten 789 and they are still counting fish," said Dave Manning, a senior environmental specialist for the Sonoma County Water Agency. "It is looking pretty good so far; that is an encouraging sign."

The count is more than double the number at the same time last year, when the entire spawning run totalled only 1,100.

"It is still early, only halfway through the run," said Bill Sydeman, Farallon Institute president and senior scientist. "At this stage, we need to be cautiously optimistic."

The increasing number of fish also raises concerns that chinook will be landed accidentally or intentionally by fishermen, since this is also the beginning of the run of steelhead, which can be caught legally.

A state Department of Fish and Game warden last Monday cited a fisherman who landed a chinook in the Russian River upstream from Steelhead Beach.

Warden Demitri Esquivel said the fisherman admitted catching the fish after Esquivel found the salmon hidden under some rocks.

"I believe he was taking the fish intentionally, but he might have been fishing for steelhead as well," Esquivel said.

Chinook are on the federal Environmental Protection Agency's threatened species list and are protected in the Russian River, where they return to spawn from late September through mid-November.

"Poaching does happen, and we think the numbers of chinook are not robust enough to tolerate a lot of poaching," said Don McEnhill of Russian Riverkeeper in Healdsburg.

This year, with Lake Mendocino at historically low levels because of a dry spring, the state Water Resources Control Board ordered a reduction in river flows and diversions to save water in the lake for the fall spawning run.

The order resulted in conservation measures being imposed on the Water Agency's 600,000 customers in the cities and water districts from Windsor to San Rafael.

The state's order, which expired Oct. 2, left Lake Mendocino at 49,000 acre-feet of water, enough for the Water Agency to increase flows in the Russian River when the run began two weeks ago, Manning said.

"The timing could not have been better. We increased the flows when the mouth of the Russian River was opened and the fish responded — they made a beeline for their spawning grounds," Manning said.

Since 2000, the Water Agency has been photographing and counting fish at its Forestville fish ladder as they move upstream.

Chinook salmon spawn in the main stem of the Russian River, with the fingerlings going into the Pacific Ocean for two to three years, eating krill and other organisms before returning.

In 2004 and 2005, ocean conditions for food were poor, resulting in low returns of chinook the past two years.

Last year at this time, there were 326 chinook counted at the fish ladder and a total return of 1,103 fish. In 2007, there were 52 at this time and a total return of 1,963.

The highest numbers were counted in 2002, when 5,474 returned for the year, and in 2003, when 6,103 returned.

Steve Jackson, owner of King's Sport & Tackle in Guerneville, said fishermen can easily avoid a chinook, also known as a king salmon.

"If you are fishing faster water and running your artificial water lures in the riffles, the chances are not good," Jackson said. "If you are fishing a pool, you are targeting a king."

The Water Agency this year suspended its program to hire off-duty sheriff's deputies to talk to fishermen at popular Russian River access points. The program's cost was $60,000 to $80,000.

Instead, aluminum signs with pictures of chinook, coho and steelhead and an explanation of the state regulations are being posted as part of an informational campaign that is costing $10,000, according to the Water Agency.