Life gets a little better for Eel River salmon; block release boosts spring migration

Virginia Graziani

Redwood Times

A block release of water from Lake Pillsbury into the main stem of the Eel River last May appears to have helped young Chinook salmon in their spring migration while producing new data for agencies and organizations studying the effects of the Potter Valley Project diversion.

Reports from the National Marine Fisheries Services (NMFS), the California Department of Fish and Game (DFG), and Pacific Gas & Electric (PG&E), indicate that a pulse of water at just the right time, combined with an increase in water temperature, can signal young salmonids to migrate when conditions are optimal for their survival.

Representatives of those agencies reported these results to the Eel-Russian River Commission, comprised of county supervisors from Humboldt, Mendocino, and Sonoma Counties, at its most recent meeting last Monday, July 30.

This meeting was held in Eureka for the first time in many years at the request of Humboldt County stakeholders and supervisor Jimmy Smith, who chaired the commission.

Last Monday's meeting was also the last official government meeting for Smith, who resigned from the board of supervisors effective last Friday, Aug. 3 for health reasons. Smith received tributes from many participants at last Monday's meeting, among them State Assemblyman Wesley Chesbro, officials from all three counties, agency representatives, and various stakeholder groups.

Many speakers acknowledged that Smith's leadership has been essential in reviving a commission originally created decades ago, but which had become moribund over the years, until the 1990s when controversy heated up over the relicensing of PG&E's hydroelectric plant at Potter Valley.

Chesbro, for one, praised Smith's leadership in helping to find "equitable ways to distribute [Eel River] water for various users.... The commission provides a forum for dialog," he said, adding, "It hasn't always been that way."

Water from the upper Eel River was first impounded in Van Arsdale reservoir and diverted through an eight-foot in diameter tunnel to the Potter Valley hydroelectric plant since 1908. In 1922 a much larger reservoir, Lake Pillsbury, was created with the completion of Scott Dam, twelve miles upstream from Van Arsdale.

Once it leaves the Potter Valley Project the water is discharged into the East Branch of the Russian River, where it becomes part of the principal water supply for farms and towns in the Russian River watershed in Mendocino and Sonoma counties.

Following an unusually dry winter and spring in 2011-12, NMFS and DFG requested PG&E to release the 2500 acre-feet of "block water" from Lake Pillsbury set aside by the protocols of the Reasonable and Prudent Alternative (RPA), an agreement established after extensive study and negotiation as part of the relicensing process in 2002.

(Note: an acre-foot is 321,851 gallons or 43,560 cubic feet.)

The release began on May 18 with the peak amount of water released between May 19 and 20 to coincide with the new moon, as salmon prefer to migrate in darkness, and ended on May 25.

Also for the first time, warmer water from the surface of Lake Pillsbury was mixed with cold water from the bottom to be released into the river through the huge needle valve at the base of the dam.

While cold water is essential to salmonid survival in summer, warmer water in the spring encourages young fish to start moving so that they will get downstream before water in the lower Eel heats up enough to favor the pikeminnow, a non-native species that preys on juvenile salmonids.

The number of juvenile Chinook salmon passing through the DFG counting station just below Cape Horn Dam at Van Arsdale peaked at 500 when the block water peaked, NMFS lead biologist Jeffrey Jahns reported to the commission.

But while this was the highest number recorded during the spring outmigration, it was not the dramatic increase they expected. For several weeks prior to the release, between 200-400 Chinook per day had been counted and similar counts were made following the release well into June.

Although the number of juvenile steelhead did not increase significantly during the block release, a surprising result was that the migration of lamprey, the eel-like creature for which the river is named, increased to the point that lamprey clogged up the six-inch pipe used to trap and count the salmon.

Since lamprey generally travel upriver in the spring, biologists thought that in this case they were trying to get up the fish ladder at Cape Horn Dam, but were washed back by the surge from the block release and got caught in the collection pipe.

DFG senior biologist supervisor Scott Downie showed a video of lamprey climbing the fish ladder. The lamprey move up the ladder in a series of jerks, attaching themselves to the ladder's surface with their sucker-like mouths, and thrashing with their tails to propel themselves. As they go through the air pocket at the top, which salmon can jump, their tails are waving ineffectually in the air so the lamprey struggle to keep moving.

The agencies concluded that the block release did no harm to the fish and probably was helpful, and that adding warmer water significantly contributes to the health of the fishery.

In fact, water temperature now looks like the solution to the mystery of why the relatively large return of adult Chinook for the past few autumns did not result in robust juvenile migration in the spring. Apparently the young fish were lingering too long in the hospitably cool waters of Van Arsdale reservoir, missing their best chance of getting downstream before conditions favored the pikeminnow.

Hydrological data showed that at the peak of the block release, the increase in water level at Scotia was only four-tenths of a foot, or about five inches.

NMFS and DFG agreed that the spring migration was the best time for the release. They continued to oppose block releases in the fall, on the grounds that the extra water would encourage mature fish to start upstream before there is enough water in the tributaries for them to meet their spawning grounds.

At the request of the commission in its February meeting, NMFS proposed a set of standards to determine when block water release is appropriate. They recommended general rather than number-based standards for greater flexibility, since river conditions are different every year.

Standards would call for a block release during a low rain year, after mid-April when release would be most beneficial for fish in the stretch between the dams and the confluence of the main stem and Middle Fork; that warm water should be combined with colder water, that the release occur during the new moon, that flows from tributaries be considered, and that the release should mimic snowmelt or rainfall events.

Scott Greacen, executive director of Friends of the Eel River, said he wanted to express FOER's "sincere appreciation for the block water release.... This is a forward-looking and hopeful step," he said, and added, "We're looking forward to 10 years from now with the de-licensing of [PG&E's Potter Valley Project] and the removal of the dams."

Potter Valley vintner Guinness McFadden responded to "my friend Scott Greacen" by noting that the block release and warm water infusion that are helping the salmon depend upon the dams.

Downie's report focused on encouraging signs of improvement in various fisheries. Members of his staff have just completed the yearly "Death March," a five-day underwater count of fish in the Middle Fork. They found 1100 returning summer steelhead, the largest count in decades.

While numbers of Chinook have been increasing, Downie pointed out that they are still only a fraction of historic counts. For example, historically Tomki Creek, the first major tributary below Van Arsdale, saw as many as 4000 spawners in a season "but now we're excited to see 50," Downie said.

Low water levels in tributaries due to inadequate rainfall, particularly in the upper Eel, continues to be a problem as fish in the main stem can be swept past their spawning grounds.

The third year of a "random study" of the South Fork Eel is showing an increase in coho and steelhead, Downie said.

When PG&E senior consulting scientist Paul Kubicek gave his report on pikeminnow monitoring, commission chair Smith once again criticized PG&E for abandoning their suppression program.

Pikeminnow monitoring and suppression is required by the RPA, but PG&E stopped their efforts because while attempting to net and electroshock pikeminnow in Van Arsdale reservoir, they killed some juvenile steelhead, a threatened species under the federal Endangered Species Act.

Smith strongly suggested that PG&E talk to other agencies, especially the Department of Reclamation in Sacramento, which has conducted pikeminnow suppression in the Sacramento River, where the predatory fish is a native species.

Suppression is essential because there is evidence that pikeminnow have been entering other watersheds in the Humboldt Bay area on "cells" of fresh or brackish water that occur in the winter, and could potentially move through local waterways to enter the Mad River as well, Smith said.

He introduced Phil Barrington, a DFG biologist, who reported on pikeminnow found in the 17th hole of the Eureka golf course near Martin Slough. During high tides and winter storms, water from the mouth of the Eel River "just scoots" (in Smith's words) into Humboldt Bay.

Recent studies show that pikeminnow can tolerate a certain amount of salinity, Barrington reported, and therefore the mixture of fresh and salt water during high water events gives them an opportunity to move into other watersheds.

He outlined a scenario in which the pikeminnow could travel from Martin Slough to the Elk River, Freshwater Creek, Jacoby Creek, and into the estuary of the Mad River.

This could be particularly devastating to coho, the most sensitive of local salmonid species, because the Humboldt Bay tributaries are a "stronghold for coho," Smith said.

At the end of the meeting, the commission unanimously voted to appoint current vice-chair Carre Brown, representing Mendocino County, as the chairperson to replace Smith. Sonoma County representative Mike McGuire will be the next vice-chair.

Smith said his alternate, 2nd district supervisor Clif Clendenen, will take his seat on the commission for the rest of the year. The Humboldt County supervisors will appoint a new representative in January, 2013.

Supervisors-elect Estelle Fennell from the 2nd district and Rex Bohn from the 1st district, who was just appointed by state governor Jerry Brown to complete the rest of Smith's term, were present in the audience.

The Eel-Russian River Commission will hold its next meeting in late October or early November at a time and place to be announced.