[2] Summer Chinook Corralled By Spill Problems At Lower Snake Dam
The court-ordered spill program to aid juvenile fall chinook on the lower Snake was the likely culprit for stalling the adult run that was heading back to Idaho. By the end of last week, the Corps of Engineers had cut spill drastically at Little Goose Dam to help more than 2,000 adult chinook get past the dam and move upstream toward Lower Granite Dam where fish passage seemed to be OK. The change in strategy seemed to be working.
But the new program had problems from the very beginning. Adult fish counts at Little Goose plummeted drastically after the spill program went into effect June 20, from over 400 to only 65 fish. It stayed mostly in double digits until June 29, when spill was cut slightly and adult passage bumped up to 154 adult chinook.
A conversation on June 20 between Corps biologist Rock Peters and the plaintiff groups' lead attorney and his technical consultants resulted in even more spill reductions. Peters estimated that about 2,200 summer chinook were stuck below Little Goose, which is more than half the number that have made it past all four dams since the official summer count began June 18. Fish numbers had also dried up at Lower Granite since the run bottled up. Only 71 adults were counted there on June 29.
The summer migration of adults in the lower Snake is not usually impacted by spill, since spill is stopped altogether at most Snake dams to maximize the collection and barging of juvenile fall chinook. But an injunction won by the plaintiff groups in the hydro BiOp litigation (NWF vs. NMFS) to add summer spill at the dams was upheld in the 9th U.S. Circuit Court of Appeals after they argued that more spill would improve fish survival in this low flow year. Opposing this, the feds had argued that barging was the least risky strategy this year because of lethal water temperatures expected later this summer.
However, the order called for spilling all water in excess of station service at the three collector dams. With summer flows in the 50-kcfs range, spill would range from about 64 to 70 percent of the water passing the dams.
The new program had problems from the very beginning when the spill regime at Lower Monumental Dam created illegally high dissolved gas levels all the way to Ice Harbor, the lowest dam on the Snake. Changes in the spill pattern helped to solve that problem. But gas problems could crop up again later this summer, Peters said, when flows diminish to about half their current levels and air temperatures increase.
Big Bad Back Eddy
Biologists think the fish passage problems at Little Goose were caused by a large back eddy in front of the dam created by the spill. Under normal conditions, the eddy doesn't exist because large flows are coming from the powerhouse at the other end of the project's tailrace to counteract the current created by the spill. But the large eddy, when it exists, creates flows that are directed into the entrance of the adult fish ladder. If this condition exists, biologists say returning adult salmon may lose their sense of upstream direction and miss the ladder.
To remedy the problem, spill at Little Goose was cut to 50 percent of the flow on June 29, which was followed by a tripling of fish numbers to 154. But Corps biologists said that wasn't good enough. After a June 30 consultation between Corps officials, plaintiffs' attorney Todd True, and biologist Bob Heinith and hydrologist Tom Lorz from the Columbia River Inter-Tribal Fish Commission, the strategy was again modified.
They decided to cut spill drastically between 4 a.m. to noon to only 7 kcfs, and to release water from both ends of the spillway, a four-fold reduction from the previous day when overall flows hovered around 60 kfcs. From noon to 8 p.m., spill would then be boosted to 30 percent of flows and after 8 p.m., it would be raised to the court-ordered level.
Corps biologist Peters said if that didn't work to get the fish moving, more drastic measures would have to be taken. The spill reduction last Thursday seemed to have a positive effect; about 1,600 chinook passed the dam that day--ten times the previous day's number.
Corps' spokesman Witt Anderson said about 600 fish passed in one hour alone when spill was reduced to the 30 percent level. He said it seemed to break up the big eddy below the dam and get the fish headed towards the ladder.
Anderson said anecdotal reports even suggested that sports fishermen along the shore suddenly started catching fish when the spill level went down. He said it's likely the Corps will suggest a near-term action of 30 percent spill through the day and ramped up to the gas cap at night.
Anderson said the fish counters at Little Goose reported that the fish looked "pretty beat up" from the days spent milling about below the dam. And NMFS technician Jerry Harmon told NW Fishletter that an ESA-listed sockeye he examined at Lower Granite the previous day looked "pretty ragged around the edges" and showed evidence of seal bites. The five-pound fish still had more than 400 miles to swim to reach its spawning grounds at Redfish Lake. It's only one of four sockeye counted so far in the lower Snake out of 66 expected to enter the mouth of the Columbia this year.
The movement of the fish had fish biologists breathing a bit easier, but they must still agree on future actions. If all parties can't agree on a course of action, the issue will have to be resolved back in federal district court, where Judge James Redden has so far stayed out of the latest scramble over spill.
But federal attorney Fred Disheroon said June 30 that he thought the judge should be informed of the situation "before he reads about it in the papers." Late last Thursday, Earthjustice attorney Todd True sent a "joint report" to Judge Redden that said the parties were cooperating to resolve the adult passage issue and didn't need the court's help "at this time."
Others were not so kind. In fact, Portland attorney James Buchal said defendants should go back to court to have the injunction quashed because it's having an obvious adverse effect on salmon. Buchal, who represented several irrigators associations in the BiOp, said the blocked migration should show the judge how wrong the "so-called experts" who testified on behalf on the plaintiffs were when they argued in support of the summer spill strategy.
"This is another example of the law of unintended consequences," said Shauna McReynolds, deputy director of the Pacific Northwest Utilities Conference Committee. "We've got to leave river operations to the experts. You can't expect to pull one switch without affecting other parts of the river. It's a carefully balanced system."
The high spill rates have been very effective at getting juveniles over the dams, said biologist Peters, but another consequence of that is the relatively small numbers of juvenile fish that are being collected for barging. He estimated that only 10 to 20 percent of the run may be barged from now on if current spill levels continue for the rest of the summer. The court order calls for spill to end Aug. 31.
Environmentalists had argued that their spill proposal would "spread the risk" to the fall chinook migration by putting about half of them in the river. The feds had expected to barge about 95 percent of the run before the judge stepped in. But barging proponents can still take comfort in the fact that the comparatively large juvenile migration seems early this year, which means more than 2.6 million subyearling fall chinook have already been barged out of the Snake this year out of about 2.9 million collected at dams on the Snake. Last year at this time, less than one million young fall chinook had been transported through the hydro system. By the end of the 2004 migration season, about 1.56 million juvenile fall fish had been barged.
Meanwhile the hitch in the adult run seems to have been fixed. Another 800 chinook passed Little Goose on July 1 and 349 more on the following day, before numbers dwindled to just 57 fish on July 5. Since then the count is back in the three-digit range with about 200 summer chinook a day still heading up the Snake from its confluence with the Columbia. -B. R.
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