TUCSON, Ariz.— The groundwater level has run dry in one of the court-ordered monitoring wells that protect federal water rights for the San Pedro Riparian National Conservation Area in southern Arizona, according to new data from the U.S. Geological Survey.

“What more proof do our leaders need that the San Pedro is being sucked dry?” said Robin Silver, a co-founder of the Center for Biological Diversity. “Years of inaction and relentless over-pumping in Fort Huachuca and Sierra Vista are pushing the river and the extraordinary plants and animals it sustains to the brink. Arizona and the federal government must act urgently and decisively to save this ecological treasure from extinction.”

Geological Survey data from the Summers groundwater monitoring well shows a reading of D — for dry — on June 30, 2025, meaning the water table dropped below the depth of the well.

When Congress created the 57,000-acre San Pedro National Riparian Conservation Area in 1988 it required that federal water rights be reserved to protect the San Pedro River and its globally important aquatic and riparian biodiversity. Court rulings in 2023 and 2024 quantified those water rights and required that groundwater levels be maintained at nine monitoring wells.

The Summers monitoring well is located next to the San Pedro River, approximately 7 miles north of Fort Huachuca. Two other groundwater monitoring wells, Boquillas 1 and Boquillas 2, both a mile from the U.S. Army fort, also show declining water levels in violation of the court-ordered threshold. New data also shows that the water table under the base itself continues dropping, diminishing baseflow in the river.

To date, seven of the 13 required water levels and stream flows have been violated, with two additional wells trending downward and nearing that threshold.

These shortfalls amount to a theft of water from the San Pedro Riparian National Conservation Area’s federally reserved water rights.

The declining water levels show that historic cumulative groundwater pumping of approximately 2 million acre-feet is overtaking efforts to mitigate the excessive water use. Fort Huachuca, the single largest user of San Pedro River water, has taken 400,000 acre-feet since 1940.

The base continues growing and “the missions at Fort Huachuca are expanding,” despite a federal appeals court siding with conservation groups in their challenge to the U.S. Fish and Wildlife Service granting fake groundwater credits to the base.

“A sprawling, thirsty army base has no place in one of the Southwest’s most biologically rich desert ecosystems,” said Silver. “The Army has been ignoring warnings about Fort Huachuca’s water problem for decades. It has downsizing plans prepared. It’s time to act.”

The San Pedro River is the last free-flowing desert river in the Southwest. Endangered species that depend on it include the Southwestern willow flycatcher, Huachuca water umbel, desert pupfish, loach minnow, spikedace, yellow-billed cuckoo, Arizona eryngo and northern Mexican garter snake. Millions of neo-tropical songbirds rely on the San Pedro to complete their yearly migrations.