RENO, Nev. (AP) — U.S. wildlife officials say there’s enough evidence a rare fish along the California-Nevada line may be at risk of extinction to warrant a yearlong review to determine if it should be listed under the Endangered Species Act.

Conservationists who petitioned for protection of the Fish Lake Valley tui chub in March 2021 say dwindling populations of the 5-inch-long (13-centimeter-long) olive-colored minnow remain in only one basin in Esmeralda County halfway between Reno and Las Vegas.

They primarily blame over-pumping of groundwater to irrigate farms and livestock pastures for a dramatic shrinking of its habitat in the drought-stricken West, where water shortages threaten numerous other species.

“Over exploitation of groundwater is a huge threat to these fish and the spring they call home,” said Krista Kemppinen, a scientist at the Center for Biological Diversity who co-authored the petition.

The U.S. Fish and Wildlife Service announced its positive 90-day finding this week.

“The petition presents substantial scientific or commercial information indicating that listing the Fish Lake Valley tui chub as an endangered or threatened species may be warranted,” the finding published in Tuesday’s Federal Register said.

Threats to the fish include effects from agriculture, encroachment of aquatic plants, geothermal energy, lithium mining and climate change, it said. A full-blown review of its status is due next August.

Lake Valley’s groundwater levels have declined as much as 2.5 feet (76 centimeters) per year over the past half-century, causing a cumulative drawdown of more than 75 feet (23 meters) since 1973, the petition said.

The consultant Esmeralda County hired to develop its water resource plan in 2012 warned the Fish Lake Valley basin “is experiencing irreparable damage from water production that exceeds annual recharge.”

“This overdraft is resulting in a collapse of aquifer storage,” Reno-based Farr West Engineering said then.

Nevada Farm Bureau Executive Vice President Doug Busselman said most local farmers and ranchers probably haven’t heard of the tui chub. But they’ve long been concerned water is over-appropriated there — which means, at least on paper, rights have been granted to more water than actually exists.

“In the years I’ve been down there, I have been hearing different accounts from domestic-well owners who are concerned because they have to dig deeper wells,” Busselman said Wednesday.

The petition should serve as “notice for people to become aware and study it and try to find out what can be done about the underlying problems,” he said. “This isn’t the first petition we’ve been through and won’t be the last.”

Busselman said federal involvement often is counter-productive because regulatory responses can take years.

“It’s a lot easier to work through a state process that deals with the laws of water rights vs. having to contend with … an Endangered Species Act kind of thing,” he said.

The petition said climate change is contributing to threats to water supplies across the West that support fish like the one in Nevada.

Average temperatures are rising and eight of Nevada’s 10 warmest years since 1895 have occurred since 2000. The frequency and intensity of drought is expected to continue to increase and snowpack decrease 30-50% by 2100 in most basins, according to a 2020 state climate study.

Western fish that are already listed under the Endangered Species Act and face increasing threats from drought include Chinook salmon in California’s Central Valley, the Rio Grande silvery minnow in New Mexico and the San Pedro Gila chub in southern Arizona.

USFWS said when it listed the San Pedro Gila chub in 2005 that it was one of only two native fish species remaining in the San Pedro River, which historically supported at least 13. The agency cited groundwater pumping for agricultural and municipal uses as a contributing factor to the loss of Gila chub.

Kemp pointed to a 2020 study published in the online journal Nature Sustainability, and cited by the U.S. Agriculture and Interior departments, which concluded 53 fish species were at increased risk of imperilment or extinction due to water flow depletion caused primarily by irrigation of cattle and feed crops in the U.S. West.

“With water dwindling across the West, there could be a flood of new aquatic species petitions in coming years, as more and more aquatic species face extinction,” said Patrick Donnelly, the center’s Great Basin director. “The Fish Lake Valley tui chub and least chub (another imperiled subspecies) are just the tip of the iceberg.”

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