TUCSON, Ariz.― A previously undisclosed 2010 report commissioned by the U.S. Army showed that groundwater pumping at Fort Huachuca was already causing harm to the San Pedro River and its endangered wildlife in 2003. The report was never given to the U.S. Fish and Wildlife Service, which decided in 2014 to approve the base’s groundwater pumping for another decade.

The 2010 report, obtained by conservation groups, is part of a notice of intent to sue filed today against the U.S. Army and U.S. Fish and Wildlife Service to prevent further damage to the San Pedro River and its endangered species from excessive groundwater pumping in the Fort Huachuca area.

The notice challenges Fort Huachuca's 2014 environmental clearance authorizing local groundwater pumping connected to the San Pedro River to serve military operations through 2024. The base’s future is also imperiled by local governments’ failure to keep their promise to “balance the area’s water deficit by 2011.”

“This report makes clear that Fort Huachuca should’ve been downsized in 2014 rather than given the green light to keep damaging the San Pedro,” said Robin Silver, cofounder and board member of the Center for Biological Diversity. “Groundwater pumping is killing this beautiful river while Sierra Vista, Cochise County and the state of Arizona all refuse to help reduce groundwater use by base contractors and personnel.”

The San Pedro River is the last free-flowing desert river in the Southwest. Endangered species dependent on the San Pedro include the southwestern willow flycatcher, Huachuca water umbel, desert pupfish, loach minnow, spikedace, yellow-billed cuckoo and northern Mexican garter snake.

“Millions of neotropical songbirds pass through this area during their spring and fall migrations and they depend on the San Pedro,” said Mark Larson, president of the Maricopa Audubon Society. “This area is too fragile to support the Fort and its surrounding population. Everything but the proving grounds can be moved to other military bases without losing national defense capabilities.”

The Fish and Wildlife Service was unaware of Fort Huachuca’s 2010 report when it issued its 2014 biological opinion authorizing groundwater pumping to support base operations through 2024. Revelation of the report would have undoubtedly led to base downsizing.

“The San Pedro River is a national and international treasure and we’ll do everything we can to save it,” said Sandy Bahr, director of the Sierra Club’s Grand Canyon Chapter. “Federal officials must ensure that groundwater pumping is reduced to levels that keep this unique wildlife corridor alive.”

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

Today’s legal filing 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.