TUCSON, Ariz.― Conservation groups sued the Trump administration today to prevent further damage to Arizona’s San Pedro River and its endangered species from excessive groundwater pumping in the Fort Huachuca area, including nearby Sierra Vista.

Today’s lawsuit against the U.S. Army and U.S. Fish and Wildlife Services challenges the agency’s 2014 decision authorizing groundwater pumping connected to the San Pedro River to serve military operations at Fort Huachuca through 2024. The lawsuit, filed in U.S. District Court in Tucson, says the base’s future is imperiled primarily by the Fort’s failure to reduce the off-post groundwater used by its troops and contractors.

The city of Sierra Vista and Cochise County promised to help the Fort by balancing their water-use budget by 2011. They have failed to do so.

“Arizona’s last free-flowing river is being sucked dry because the Army refuses to downsize Fort Huachuca and ignores all the evidence showing that it must,” said Robin Silver, cofounder and board member of the Center for Biological Diversity. “It’s heartbreaking that the San Pedro and its irreplaceable wildlife are being sacrificed because the Fort and local governments refuse to reduce groundwater use. They’re willfully killing this beautiful river.”

A previously undisclosed 2010 report commissioned by the U.S. Army showed that groundwater pumping attributable to Fort Huachuca ― including water use on and off the military base ― was already causing harm to the river and its endangered wildlife in 2003. The Fish and Wildlife Service failed to consider the key findings of this report before it decided in 2014 to approve the base’s groundwater pumping for another decade.

The Fort’s unchecked groundwater pumping harms threatened and endangered species that depend on the San Pedro and its lush riparian habitat, including the southwestern willow flycatcher, Huachuca water umbel, desert pupfish, loach minnow, spikedace, yellow-billed cuckoo and northern Mexican garter snake.

“In the midst of an extinction crisis the Army and local officials are wiping out one of the country’s environmental crown jewels,” said Mark Larson, president of the Maricopa Audubon Society. “Every year millions of birds migrate through this region, which is critical to the long-term survival and recovery of endangered species. This fragile river will be lost forever if the Fort doesn’t act quickly to reduce groundwater use.”

The Fish and Wildlife Service, unaware of Fort Huachuca’s 2010 report findings, issued a 2014 biological opinion authorizing groundwater pumping to support base operations through 2024.

Today’s lawsuit also challenges the biological opinion’s reliance on illusory water savings and credits, as well as its failure to account for lower-than-anticipated water recharge. In addition, the notice challenges the Service’s failure to account for a nearly 62% increase in groundwater pumping attributable to the base, as well as its failure to account for the state approving 369 new wells in the Fort Huachuca area.

This is the ninth challenge since 1994 to Fort Huachuca and its threat to the San Pedro River in violation of environmental laws. All the court challenges have been successful.

“For years the Fort has evaded the Endangered Species Act by disregarding the science and relying on illusory water credits,” said Earthjustice attorney Alex Hardee. “We filed this lawsuit to put an end to this pattern and practice, and to force the U.S. Army and Fish and Wildlife Service to comply with the Endangered Species Act.”