A federal judge has directed the U.S. Department of the Interior and an irrigation corporation to stop diverting water from the Upper Clark Fork River near Deer Lodge to prevent harm to endangered bull trout.
U.S. District Court Judge Brian Morris on Wednesday issued a temporary restraining order in a suit brought by two organizations, Save the Bull Trout and Alliance for the Wild Rockies, that alleges Interior and West Side Ditch Company are violating the Endangered Species Act in order to preserve the Grant-Kohrs Ranch National Historic Site.
The National Park Service-operated historic site is a 1,618-acre working cattle ranch that was dedicated to commemorate the country’s frontier cattle era.
According to court filings, the federal government irrigates more than 400 acres of Grant-Kohrs to grow hay and maintain livestock pastures, holding seven water rights for irrigation and 16% of shares in the Westside Ditch Company, one of five irrigation systems used to convey water to the site.
The West Side Ditch diverts water from the Upper Clark Fork near Deer Lodge and conveys it more than 12 miles to Grant-Kohrs. The diversions can take up to 90% of water from the river during severe drought years, according to court filings.
But a huge swath of the Upper Clark Fork — 62.8 miles — is designated as critical habitat for bull trout by the U.S. Fish and Wildlife Service.
In 1998, bull trout were listed under the Endangered Species Act, and in 2010, Fish and Wildlife Services established critical habitat units for the species, including the Clark Fork near Grant-Kohrs.
The Daily Montanan reports that in the lawsuit, the organizations allege Interior and West Side are diverting too much water from the river during parts of the year when streamflows are low, further reducing habitat for the endangered trout, which could “adversely affect” the species’ survival.
“In most years, the West Side Ditch takes 50% or more of the Upper Clark Fork flow in mid-to-late summer. In drought years, as in this summer, the diversion has been taking an even greater share of the river’s flow. There is simply not enough water left in the Upper Clark Fork River after this diversion,” said Michael Garrity, executive director for Alliance for the Wild Rockies, in a statement. “The extent of dewatering has altered bull trout critical habitat so adversely that the species can no longer survive in that portion of the Upper Clark Fork, much less migrate to headwaters streams to spawn.”
Neither the National Park Service nor the Department of the Interior commented on litigation.
The two plaintiffs filed a similar lawsuit in 2022. In that case, the Interior Department ultimately entered a settlement where the federal government would fund multi-year projects to upgrade the West Side Ditch so bull trout wouldn’t swim into the irrigation ditch and return flows wouldn’t degrade the river. The settlement included an agreement that if the federal government did not fund the projects to completion, the plaintiffs could return to court. Under the Trump administration, the Interior Department “stopped funding the projects to replace the WSD diversion,” court documents state, giving rise to the current suit.
As part of the previous lawsuit, Fish and Wildlife Services established a 90 cubic feet per second (cfs) minimum flow for the Upper Clark Fork near Deer Lodge, where West Side diverts water in order to “maintain self-sustaining wild trout populations and the macroinvertebrates that support them.”
The federal agency also stated that if Grant-Kohrs Ranch does not irrigate when streamflows are below 90 cfs, leaving DOI’s share of water rights in the river, it would have a “significant impact” on maintaining the existing streamflows.
Over the last 30 days, streamflow data collected by the U.S. Geological Survey show that the Upper Clark Fork has run well below 90 cfs, dropping to 34.3 cfs on September 9.
The lawsuit ultimately seeks a preliminary injunction to prevent the Interior and West Side form diverting water when streamflow falls below 90 cfs.
But West Side has argued in court filings that it would suffer from both a temporary halt and from an injunction, claiming agricultural and livestock losses.
In ruling on the temporary order, Morris wrote that the harms to endangered bull trout outweigh the ditch company’s argument, considering the irrigation season is “nearly complete.”
Morris has scheduled a hearing on the preliminary injunction for Sept. 25 in Helena’s federal courthouse.
“We have millions of cattle and thousands of hay fields in Montana, but there are very few bull trout left, especially in their historic spawning areas of the Upper Clark Fork River,” Garrity said. “Considering the Clark Fork River was a healthy river full of bull trout when the original Grant-Kohrs Ranch was founded in 1862, the question is whether the Park Service should destroy bull trout critical habitat for a historic ranch display when simply growing less hay can help return the Clark Fork to a living river where bull trout can once again survive, spawn, and avoid extinction.”
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