Operators of an Oregon ranch fear its irrigation supply is under threat from an Endangered Species Act lawsuit alleging its dam blocks upstream fish migration.

WaterWatch of Oregon, an environmental nonprofit, has filed a federal complaint accusing Q Bar X Ranch of unlawfully harming threatened salmon by operating its Pomeroy Dam near Kerby, Ore.

The lawsuit seeks an injunction requiring the ranch’s owners to either remove the dam or install a fish passage that meets state and federal regulations.

“The Pomeroy Dam is a passage impediment and hazard for migrating adult and juvenile Southern Oregon Coast Coho on the Illinois River,” the plaintiff claims.

All the ranch’s irrigation water is drawn from the reservoir above the dam, which it primarily needs for grass hay, according to a member of the ranch family who refused to be named.

Losing that water would be “devastating” to the ranch, whose owners may not find an alternative source of irrigation, he said. “We’ll cross that bridge if we come to it.”

Pomeroy Dam has existed since the 1940s but its removal has recently become an objective for the environmental group, the family member said.

“They just really don’t want to have any dams,” he said. “I don’t see the logic of it.”

The Oregon Farm Bureau isn’t directly involved in the lawsuit but is concerned the case may represent a new litigation strategy for WaterWatch, said Mary Anne Cooper, its vice president of government affairs.

“I think this will be another tool in WaterWatch’s tool box,” she said. “From a precedent standpoint, we will definitely be paying attention to the case.”

The lawsuit may be a foreboding sign for other irrigators who rely on private water impoundments, Cooper said. “You can get hauled in and even if the lawsuit is baseless, you can have to spend hundreds of thousands of dollars proving that.”

According to WaterWatch, the structure violates the Endangered Species Act’s prohibition against “take” of protected fish. That includes killing them or harming them through “significant habitat modification.”

“The passage impediment and dam hazards impede migration and spawning as well as causing direct harm to Southern Oregon Coast Coho,” the complaint said.

Apart from preventing salmon from reaching about 100 miles of “high-quality spawning and rearing habitat,” the dam has raised water temperatures to their detriment, the complaint said.

The dam has created “pool conditions” that increase predation on juvenile salmon, the complaint said. Meanwhile, “inadequate screening” of the irrigation diversion causes adult fish to get stranded and die in irrigation canals and ditches.

Upstream fish passage past Pomeroy Dam is a top priority for state wildlife regulators but the ranch owners have rejected the plaintiff’s offer to remove the barrier for no charge, according to the lawsuit.

“WaterWatch’s experience with reaching out to defendants causes WaterWatch to be concerned that defendants will refuse and fail to respond to this complaint and/or to any order of this court to remove or fix the Pomeroy Dam,” the plaintiff said.

If the ranch owners don’t fix the impediment themselves, the environmental group wants a court order allowing its representatives to access the property and remove the dam.

“WaterWatch has extensive experience with obtaining funding and working with expert contractors on dam removal throughout Oregon,” the complaint said.

The lawsuit also seeks compensation for the nonprofit’s litigation expenses.

Traditionally, WaterWatch has focused on disputes over water rights and other aspects of state water law, said Cooper of the Oregon Farm Bureau.

The challenge to Pomeroy Dam’s legality was filed in federal court, which may indicate the organization is turning toward ESA claims, she said. Several years ago, the group also partnered with the Earthjustice nonprofit law firm in an irrigation-related lawsuit over the Oregon spotted frog.

The lawsuit against Q Bar X ranch is also noteworthy because it’s filed against a private landowner, rather than an irrigation project with a federal nexus, Cooper said.

“It’s much less common to see a direct take allegation against a private diversion,” she said. “It’s not totally unprecedented but it is uncommon.”

Litigation over federal water projects typically centers on whether the government properly analyzed their impacts to avoid jeopardy to threatened and endangered species, Cooper said.

The lawsuit against Q Bar X ranch instead alleges the owners actually caused “take” of protected fish — an allegation that faces a tough evidentiary threshold, she said. “It’s a pretty high burden to prove take against a private party.”