A study has determined that removing the causeway at Bateman Island in Richland could have a significant impact on water temperatures in the area. And that could be good for the salmon population.
Computer models show the area west of the land bridge near the confluence of the Yakima and Columbia rivers would have cooled by an average of 3 degrees in spring 2012 and by 5 degrees in 2014, a lower water year, if part of the causeway were removed. Those were the two years when conditions were sampled.
The temperature difference is significant because warmer water makes it easier for predatory fish like smallmouth bass and walleye to digest food, said Geoff McMichael, an aquatics researcher with Mainstream Fish Research LLC.
“That just means they eat more prey items,” he said, including salmon and steelhead.
We saw sockeye salmon dying in the Columbia River in large numbers. They were unable to find the pockets of cool water they needed to move into the refuge.
Rebecca Wassell, Yakima Basin program manager for the Mid-Columbia Fisheries Enhancement Group
The difference might have been even more striking had the study been done during the 2015 drought, he said.
Removing the causeway would reduce the temperature in an area of the Yakima River delta possibly all the way to the Highway 240 bridge, McMichael said.
“If you reduce the predatory fish by reducing the temperature, the juvenile salmon population is going to go up,” he said.
Yet to be determined is whether the causeway would be fully or partly removed and how to pay for it, said Rebecca Wassell, Yakima Basin program manager for the Mid-Columbia Fisheries Enhancement Group. The next steps are complicated by the ownership of the land around the causeway.
Bateman Island and the Yakima River shoreline are owned by the Army Corps of Engineers, but the land is leased to Richland. The causeway itself is not owned by anyone, but the land under the water it crosses is owned by the state Department of Natural Resources, Wassell said. The next step is for all of those groups, as well as the Confederated Tribes of the Umatilla, to work with fisheries managers.
“At this point, it really depends on how effective the conversations are between the landowners,” she said.
The drought gave a sense of urgency to the situation, Wassell said.
“We saw sockeye salmon dying in the Columbia River in large numbers,” she said. “They were unable to find the pockets of cool water they needed to move into the refuge.”
The study was conducted between 2011 and 2015 with a grant from the Washington Salmon Recovery Board and Washington Integrated Plan. It included public meetings in Kennewick, which about 50 people attended in 2014. Another 12 people were chosen for a stakeholder committee, which met twice to give input on the causeway and potential changes.
Some fishermen at the public meetings worried about the effect removing the causeway would have on fish in the cove between Bateman Island and the shore. But Wassell said the people attending the meetings were favorable about opening up the causeway because it would make fishing from the banks for salmon easier.
It is feasible to build a bridge to the island if the causeway is removed, but the cost hasn’t been determined, Wassell said. A less-expensive option would be to build a pedestrian bridge, instead of one that can accommodate emergency vehicles.
If you go
Wassell will discuss the results of the study at the Benton Conservation District’s meeting, which is scheduled for 6 p.m. Dec. 9 at 6095 W. Van Giesen St. in West Richland. The meeting is open to the public.