A net pen trout rearing operation on the mid-Columbia has taken a devastating hit from heightened total dissolved gas levels in the river as Columbia-Snake dam operators struggle to manage brimful rivers for flood control and to protect fish.
Pacific Seafood in a May 26 letter to the Oregon-Washington congressional delegation, governors and state legislators asked for help to force changes to operations at central Washington’s Grand Coulee Dam that are stirring up gas levels that are lethal to fish.
It said that trout rearing in company net pens in Lake Rufus Woods, a shallow reservoir linked to the Columbia in the Chief Joseph Dam pool in central Washington, were dying at a rate of 100,000 fish a day. Grand Coulee Dam is the next hydro project upstream of Chief Joseph.
“If this practice isn’t stopped immediately, it will result in more than $30 million in economic damage to our company alone. There are currently 2.7 million fish still living on the fish farm that are being threatened by this environmental and economic catastrophe,” the letter said.
A Washington Joint Senate Resolution approved unanimously May 25 was in direct response to the Pacific Aquaculture (a Pacific Seafood subsidiary) predicament and incidence of flooding caused by the higher than normal output from the dams. It called for the development of alternatives to provide the reservoir capacity necessary to minimize flooding while lessening the impacts to fish resources and private, commercial fish-growing operations.
The Bureau of Reclamation and Army Corps, which operate, respectively, Grand Coulee and Chief Joseph, say they are doing their best to manage a river system that has become to great extent unmanageable.
Flows from Lake Roosevelt is being released through Grand Coulee Dam’s outlet tubes to create space for the largest snowpack in the Northwest since 1997. A cool spring has slowed the snowmelt but wetter than normal weather patterns have pushed up river flows across the Columbia-Snake river basin and forced flood control operations.
Based on flood control requirements, Reclamation is maintaining lower lake levels to reserve space for the expected spring thaw.
“Our first concern is public safety,” said Steve Barton, the Corps’ Reservoir Control chief. “We need to release enough water now to manage the available storage space to ensure adequate room in anticipation of the higher flows expected late in the season.”
In addition to maximizing the powerhouse releases, releases through the outlet tubes are required to maintain low lake levels to capture anticipated snowmelt. As water is flowing out of the outlet tubes, air becomes trapped and creates gases (total dissolved gas) harmful to fish. These factors, unique to high-runoff years like this one, are incorporated into the environmental regulations along the Columbia River.
“We have researched all options to minimize the dissolved gas below the dam, including pumping water up to Bank’s Lake and maximizing flow through the power plant,” said Steven Jarsky, Reclamation’s acting Power Manager at Grand Coulee.
Total dissolved gas levels immediately below Grand Coulee have been above 130 percent since May 20, and above 140 since May 28. State water quality regulations cap TDG generation at 120 in the tailwater and 115 percent in the forebay at mainstem Columbia and Snake river dams during the salmon migration to protect fish and other aquatic organisms. High levels of TDG can be lethal. Most the gas is created when water plunges down from spill gates into dam tailraces.
Pacific Sea went to U.S. District Court in pursuit of a temporary restraining order and preliminary injunction preventing the Corps, Bureau and Bonneville Power Administration “from continuing certain dam operations resulting in large fish kills in the Columbia River in violation of section 9 of the Endangered Species Act, and for failure to re-initiate consultation under section 7.” The affected species include listed bull trout and steelhead, the company said.
The complaint likened its fish farm die-off fish “to a canary in a coal mine” and a “red flag.”
The most recent previous severe high discharge and high TDG from operation of Grand Coulee occurred in 1997, according to a declaration from University of California, Davis fishery biologist Ralph Elston filed by the company.
“The report on that event by Elston (1998) documented the concentrations of TDG created by use of the Grand Coulee Dam (GCD) discharge tubes were lethal to both captive and wild fish,” Elston said.
Upriver passage of listed salmon and steelhead is blocked by Chief Joseph but they do pass up and down the river through other lower river pools. Likewise listed salmon and steelhead are blocked by the Hells Canyon Complex of dams on the Snake River along the Idaho-Oregon border.
Oral argument were held before Judge James A. Redden on May 27. He found later that day “that Plaintiffs have not presented sufficient evidence that there are any threatened or endangered species below Grand Coulee Dam and above Chief Joseph Dam.
“Additionally, there is insufficient evidence that Federal Defendants' actions will harm any ESA-listed species below Chief Joseph Dam. Plaintiffs have not established a reasonable likelihood of a future violation of Section 7 or Section 9 of the Endangered Species Act. Accordingly, the Motion for a Temporary Restraining Order and Preliminary Injunction  is DENIED.”
TDG levels averaged 138.9 percent Thursday in Chief Joseph’s forebay and 122.7 percent just below the dam and have been in that range for the past week.
Monitors have seen a spike the incidence of “gas bubble trauma” for at least one dam downriver. GBT signs jumped from 1 percent May 24 to 37 percent of fish May 28 to 60 percent of fish June 2 at Rock Island Dam, which is about 90 miles downstream from Chief Joseph.
Signs of GBT at other monitoring stations are scant. At Lower Monumental on the lower Snanke River the rate jumped 4.8 percent of the fish sampled on May 25 just before an upriver powerhouse outage began to 23 percent on May 28, then dropped down to 4 percent June 1, the day Little Goose went back on.
Monitoring at Bonneville and McNary dams on the Columbia shows peaks of 3.17 percent of fish and 5 percent respectively, with most of the sampling showing zero signs of GBT over the past two weeks. Lower Granite Dam monitoring turned up all zeros.