A new fish ladder has opened a long-blocked fishway at Skaha Lake Dam in British Columbia, creating a huge jump in sockeye returns in the Okanagan Basin, Bonneville Power Administration has announced.
Last month staff from the Colville Tribes and Okanagan Nation Alliance cut 105 4 x 4 posts and set them into built-in slots in the fishway at the dam. They created five step pools, each about two to four feet deep, each about an 8 to 12 inch leap above the last.
Then they removed the existing stop log. Water flowed into the fishway, and salmon that were once limited to rearing in the north basin of Canada's Lake Osoyoos now had access to Skaha Lake. Okanagan sockeye rearing habitat more than doubled in a project estimated to cost only around $2,500.
The story how of a fishway - built in the 1950s and immediately boarded up again - was finally re-opened just this year, involves a study and implementation plan that BPA funded in the early part of this century that helped convince biologists that it was the right thing to do, and years of building trust and common goals between utilities and tribes in the United States and Canada.
Skaha Lake Dam was part of a Canadian flood control and irrigation project that also includes McIntyre Dam downstream at the outlet of Vaseux Lake and Okanagan Lake Dam upstream at the outlet of Okanagan Lake.
Both Skaha Lake and Okanagan Lake are prized for their native kokanee. They grow to 10 pounds and supply a lively recreational and commercial fishery. Fish managers were worried about sockeye getting into the lakes, where they believed the fish could compete with the kokanee and native trout for food and habitat, and potentially spread disease. They also wanted to keep non-native warm-water species from getting into the upper reaches of the Okanagan River. So, soon after the dams were built, they closed off passage into both of those lakes.
As the Colville Tribes watched sockeye runs in the United States dwindle in the 1990s, though, they wondered if the limited rearing area in Canadian lakes wasn't part of the problem. The mid-Columbia public utility districts of Douglas, Chelan and Grant counties, for their part, had mitigation responsibilities for the sockeye that migrated past their dams. They began to form alliances with the Okanagan First Nations and the Canadian governmental entities, including the Department of Fish and Oceans. A 12-year plan started to take shape.
In 2000, they approached BPA with a request to fund a risk assessment of their proposal to open up access to Skaha and Okanagan lakes. BPA agreed to fund a $800,000 three-year study. The study found that there was negligible disease risk to native stocks from providing passage over McIntyre and Okanagan Falls into Skaha Lake. Follow up studies found there was plenty of food in the Lake to support a sockeye population without jeopardizing kokanee populations.
The studies were timely, thorough and scientific, and the findings reassured those that were worried about opening up Skaha Lake, said BPA. The partners took it stepwise, ensuring buy-in and assessing results at each stage. In the fall of 2009, the fish managers gave the "okay" to modify McIntyre Dam to provide passage, with $1.4 million in mitigation funds from Grant County PUD. Then in 2014, they agreed to activating the fish ladder at Skaha Lake.
It's likely that the fishway at Okanagan Lake Dam will be a lot less time in the activating, says Colville fish biologist Chris Fisher. Later this summer, the tribes will put in gravel ramps immediately downriver of the dam where the returning sockeye can spawn.
The 2014 sockeye return to Bonneville Dam is the largest on record (since 1938). Some of those fish are headed for the Snake River, where a BPA-funded hatchery program has brought the sockeye back from the brink of extinction. They're also helped by fish passage improvements on the federal hydropower dams that have improved juvenile fish survival to the best seen since pre-dam days.
Source: Bonneville Power Administration
