The U.S. Army Corps of Engineers this week announced plans for implementing operations at the lower Columbia's Bonneville Dam aimed at easing downstream passage for steelhead kelt, which are spawned out fish heading back toward the estuary and ocean to repair themselves for, perhaps, a return to freshwater for another try at reproduction.

Recent technical discussions among federal, state and tribal officials have resulted in the development of a set of "triggers" that, when pulled, would prompt the opening of the corner collector at the dam's second powerhouse to provide a surface passage route downstream for the kelt.

The collector is the powerhouse's ice and trash sluice chute, which was retrofitted at a cost of $50 million to provide another non-turbine passage route at the dam for, primarily, juvenile salmon and steelhead. The renovation, completed in 2004, has proven efficient at attracting juvenile fish and provides the most benign passage route at the dam.

But, when opened, the chute channels 5,000 cubic feet per second of water from the forebay to the tailrace with a bit of a splash. That ups levels of total dissolved gas in the river.

Spill at lower Columbia mainstem dams, including Bonneville's spillway, is scheduled to start April 10 and would provide the kelt and juvenile fish another passage option.

The triggers to be used in 2010 say that if two kelt are seen at the dam on two consecutive days and when there are 20 kelt sightings overall in a season the corner collector will be opened to provide a surface passage route.

As of Wednesday the first trigger had been achieved. But only eight kelt have been seen so far in the season, the Corps' Dan Feil told the Technical Management Team.

When the count reaches 20, the corner collector will be opened but perhaps not for long. TDG readings at the Warrendale gauge six miles downstream of the dam have been holding at about 104-105 percent, and at this point in time Oregon state water quality standards require that TDG be limited to 105 percent in near-shore areas with water less than 2 feet deep.

(The Corps did have cause to pause by Friday when Warrendale readings pushed above 106 percent. If the TDG level stays above the allowable standard, the corner collector could well stay closed until April.)

Opening the corner collector has the effect of raising TDG levels by about 2-3 percent, Feil said.

Elevated TDG levels can negatively affect aquatic life, including fish. In the past, TMT members have been concerned that gas stirred up by the corner collector flows might cause problems for shallow water redds dug by chum salmon below the dam.

Field said the Corps planned to close the corner collector again when TDG levels reached the 105 percent limit and then shift priority power production from powerhouse 1 to powerhouse 2, which is nearer the Oregon shore. It is believed that redirecting flows to powerhouse 1 would also bring more kelt there, where they can use that powerhouse's sluiceway as a surface passage route. Steelhead have in the past shown a preference for surface oriented passage routes, Feil said.

He said it is unknown how well the steelhead kelt will fare. The sluiceway is not specifically designed for fish passage. Problems would also await the fish in the form of sea lions, which gather each spring below the dam to prey on salmon and steelhead headed upstream to spawn.

As of April 1, waivers of state restrictions allow TDG levels as high as 120 percent below the dam. That would allow a reopening of the corner collector, Feil said.

NOAA Fisheries 2008 Federal Columbia River Power System biological opinion calls on federal agencies to "evaluate operation of the Bonneville PH2 corner collector from March 1 through start of spill as a potential means to provide a safer downstream passage route for steelhead kelts, and implement if warranted." The Corps owns and operates the dam.

It says that "NOAA Fisheries considers improvement in kelt survival a key element to improving the survival of all steelhead ESUs." Because of their relatively poor post-spawning condition, kelt survival is generally considered to be quite low irregardless of what they encounter. The BiOp outlines measures NOAA Fisheries says must be implemented to avoid jeopardizing salmon and steelhead stocks – "evolutionarily significant units -- that are listed under the ESA. They include naturally produced Mid-Columbia, Upper Columbia Snake River steelhead.

The states of Oregon and Washington and the Nez Perce Tribe in March 2009 issued a request that the corner collector be opened March but were denied because of TDG and cost concerns. The collector was opened prior to the start of spill in both 2007 and 2008 for an evaluation of kelt passage via hydroacoustic monitoring.

"The data collected indicated 172 and 223 kelt sized fish passed the collector in each year, respectively. Daily passage ranged from 4 to 7 fish per day," according to the request."… the point is that these fish are present during this time and do pass the corner collector when it is open."