PORTLAND, Ore. (AP) — A coalition of environmental and fishing groups are suing a water district in southern Oregon over an aging, privately owned dam that they say hinders the passage of struggling salmon populations in the pristine North Umpqua River.

The lawsuit, filed Friday in U.S. District Court in Eugene, asks a judge to order the Winchester Water Control District to build a new fish ladder and make major repairs to Winchester Dam, which dates to 1890 and is on the National Register of Historic Places. The dam is one of the oldest in Oregon.

The aging fish ladder on the 130-year-old dam blocks the progress of migrating Oregon Coast coho salmon — a federally protected species — as well as spring and fall chinook, summer and winter steelhead, cutthroat trout and Pacific Lamprey, according to the lawsuit. There's also no record that the water district has rights to hold and store water behind the dam under state law, the lawsuit said.

Dominic M. Carollo, the water district's attorney, did not return a call for comment Tuesday.

The North Umpqua River is pristine fish habitat and is cherished by environmentalists and anglers alike, said Jim McCarthy, with WaterWatch of Oregon, one of the plaintiffs. The 167 miles (268 kilometers) of river above the dam are some of the highest-quality fish habitat in the state, he said, and are a key part of the coastal fishing industry.

The dam's fish ladder includes right-angle turns that create dead ends for fish trying to pass over the dam; fish get stuck in holes that have eroded in the outdated gravel fill; and pieces of metal injure some migrating fish, according to the lawsuit.

The dam significantly reduces the number of young salmon reaching the Pacific Ocean and is preventing returning salmon from reaching spawning grounds in the river above the dam, plaintiffs said.

“The more we learn about this old dam the worse it gets. The fact that every salmon and steelhead passing over this dam risks injury or death by exposed rebar, eroded concrete, or a pollution spill negates our work to protect fish habitat upstream," said Tim Goforth, board president of Steamboaters, another plaintiff.

The Pacific Coast Federation of Fishermen's Associations also joined in the lawsuit. That's because low numbers of federally protected Oregon Coast coho salmon can impact the commercial fishery for other types of salmon when numbers of coastal coho drop.

“Fewer coastal coho surviving the impacts of Winchester Dam only exacerbate these already stringent allocation and ocean harvest restriction problems fishing families face up and down the coastline,” plaintiffs said in the lawsuit.

The plaintiffs also raised issues about the dam's overall safety for humans, although the lawsuit only seeks to improve passage for fish.

Winchester Dam's condition was downgraded to “poor” last year by state officials who inspected it and found leaks and other issues. It is categorized as “high hazard” by the Oregon Department of Water Resources because of its condition, and repairs to the dam in 2018 led to water contamination downstream that affected drinking water for nearly 40,000 customers, plaintiffs said.

The dam was damaged by a large flood in 1964 and has not been used to generate power for decades. The 17-foot (5-meter) structure spans the entire river and is currently used to maintain a flat-water reservoir for boating and water skiing for an association of local property owners who formed the water district in 1969.