Federal biologists feel they might have found the right combination of actions at John Day Dam to lift juvenile salmon survival to standards targeted in a Columbia-Snake hydro system biological opinion that prescribes actions believed necessary to avoid jeopardizing protected fish.

Being tested for the first time this year are a "wall of water" aimed at shielding fish from predators; a vast wire "array" that is also designed to reduce predation; and relocated "temporary spillway weirs" that are expected to attract more juvenile fish to what could become the dam's safest route of passage.

The May 2008 Federal Columbia River Power System BiOp set as "performance standards" the achieving of 96 percent per dam passage survival for spring juveniles and 93 percent per dam passage survival for summer juvenile migrants. An evaluation based on 2004-2005 data showed survival for yearlings (spring chinook) and steelhead met or bettered the standard at 96 and 99 percent respectively but that juvenile fall chinook migrants were well below the standard at 86 percent.

At fault for the most part were passage routes that delivered the young fish to areas below the dam that are teeming with predatory birds and fish.

The new fish protection devices at work this year include a new flow deflector in spillbay 20 and a new wire array that covers the tailrace.

Additionally, two TSWs first installed in spillbays 16 and 17 were moved this year to bays 18 and 19, which are just one spillbay (20) removed from the dam's powerhouse.

And while the acoustic data from tagged passing fish has not yet been compiled and analyzed, it appears the hydraulic wall and TSW placement is working.

The deflector installed in bay 20 this past winter was designed to create a hydraulic wall to keep fish that are passing through the TSWs in spillbays 19 and 18 from being sucked over into the tailrace of the powerhouse. An eddy is created there when water is being spilled at the dam. The eddy has the effect of holding the young salmon below the dam and making them easy targets for predatory pikeminnow and other fishes, as well as avian predators.

The new 50-foot-long spill deflector was tested in early April before the start of spring spill at the dam.

"The deflector is doing its job so far by keeping those fish going straight down river but I don't have survival data yet showing the level of benefit," U.S. Army Corps of Engineers biologist Dennis Schwartz said. The Corps operates the dam.

"What we do know is that the deflector is performing just like the model intended and that balloon-tagged fish we released did not show up in the powerhouse tailrace."

The deflector has the additional benefit of dispersing water that is plunging down through the spillgate thus reducing the amount of total dissolved gas created in the tailrace.

The TSWs, designed to provide a more natural, surface oriented passage route, are now in their third year of tests. They are intended to draw fish away from the powerhouse, which is the least hospitable of the available passage routes. The other alternatives are the spillbays and/or TSWs and a mechanical juvenile bypass system.

"John Day has one of the lowest turbine survivals" in the Snake-Columbia river hydro system, Schwartz said.

If the TSWs prove to be effective in their new location, a decision will be made about whether to convert the prototypes to permanent structures or replace them with newly designed spillway surface weirs. The weirs were completed and first installed in the spring of 2008. They cost $1.4 million apiece to build.

By moving the TSWs closer to the powerhouse, the Corps is "trying to intercept the fish just as they're trying to decide whether to go through the powerhouse or the spillway," Schwartz said.

"We like the way the TSWs are performing," Schwartz said. Preliminary data shows that a large number of the juvenile fish that approach the powerhouse are being drawn toward the TSWs.

For the array, three 90-foot towers were installed on the Washington side of the Columbia and three 40-foot towers on the Oregon side. The array also employs two existing towers that were built during an earlier attempt to place a wire array below the dam. The array includes 128 individual "wires" for a total length of 240,000-ft of synthetic line. The longest individual span is 3,200 feet.

The array installed earlier this year covers nearly 6 million square feet or close to 137 acres. It fans out across the boat restricted zone below the dam.

Researchers have noticed that the numbers of California gulls, which have been the primary avian predator at the dam, are greatly reduced this year with the array in place. The Corps' Nathan Zorich said that in 2009 the average number of gulls feeding below the dam on any given day was 99 (a range of 8 to 314). So far this spring-summer season the average has been 14.

The peaks have seemed to coincide most closely with peak abundance of migrating juvenile lamprey, not salmon. The young lamprey are among the fish with the highest energy density so they provide very good food for the birds.

The array seems to be effectively altering the birds' habitat (airspace), Zorich said. The wires run perpendicular to the most common wind direction. That likely disrupts the birds who like to fly and/or hover facing into the wind.

The presence of the arrays has been part of a two-pronged attack. Zorich said human efforts to haze birds have been more intense this year. The hazing has been carried out over two shifts, or 16 hours, which is double the 2009 effort. The hazing is also being carried out from boats for the first time as well as from the base of the dam.

It would seem, however, that many of the birds have just moved downstream. California gull predation at The Dalles Dam is up this year, Zorich said.

He said that the population of California gulls along the coast, and in particular in the Columbia River basin and San Francisco Bay area, "has been exploding" in recent years.