In an effort to discourage birds from snatching up juvenile salmon below McNary Dam, the U.S. Army Corps of Engineers (USACE) Walla Walla District has bought a laser.
This laser emits a bright green light that creates a large dot. “Birds see the dot produced by that color of laser as a solid object moving towards them and fly out of the way because they think they are being chased or about to be hit by something,” Mechanical Engineer Caleb Willard said.
The laser has a range of about 950 ft to a mile depending on the weather. It is programmed to move in a random pattern within an area dictated by its software. Its focus is on the juvenile outfall pipe where juvenile salmon are returned to the river just downstream of the dam. This area is a Boat Restricted Zone (BRZ), so there is no danger of anyone looking at the beam, which is strong enough to damage eyesight if looked at directly.
The laser was purchased after the sprinkler that originally kept birds clear of the outfall pipe was wiped out by high water. The sprinkler had been poorly designed and had been susceptible to high water in the past. In an effort to mitigate the problem and provide better protection for the juvenile salmon, Walla Walla District biologists and engineers set out to design a better sprinkler. When the existing sprinkler was destroyed, the team started throwing out alternative ideas for deterring birds, including everything from wires to drones that could scare them away.
“We settled on a couple different innovative things that had never been tried before,” Fishery Biologist Tim Wik said.
The laser was the first of these innovative solutions. It was set up on the river bank last spring and aimed at the outfall pipe. It had some success as it was operated through the spring and summer, but the team found that it was operating at the edge of its effective range. So, a second laser was bought in September and will be mounted on the outfall pipe itself this coming spring.
The Walla Walla District also is considering purchasing a sound device (called a LRAD or Long Range Acoustic Device) that emits avian distress calls and calls from predatory birds. If purchased, it would also be installed and evaluated over the coming spring and summer.
Other USACE dams have implemented bird wires over the spillways and sprinklers near their outfall pipes. These have had some success, but birds continue to be an issue for young salmon near the dams.
As a more drastic bird deterring method, the Walla Walla District USACE and the USDA have a “Memorandum of Agreement,” by which the dams negotiate annually to have the USDA’s Wildlife Services group comes out and “haze” the birds.
During these visits, USDA employees march about, setting off fireworks and shotgun blanks, and even getting into boats to scare away birds hanging out in the water. This is effective, but only on the short term, and has to be repeated frequently. The hope is that the new laser will become a more effective and cheaper alternative to having people actively shoo birds away.
In April, the effectiveness of the new laser at McNary will be tested. If it proves itself to be good at keeping birds away from the young salmon, more may be installed at other Walla Walla District USACE dams. Ice Harbor has already expressed interest in getting one for their facility.