TUCSON, Ariz.— Four of nine monitoring wells in the San Pedro Riparian National Conservation Area have fallen below court-mandated levels in violation of federal water rights, according to new data from the United States Geological Survey. Water levels in a fifth well are on a downward trend and edging closer to a violation.

“This new data show how extremely dire the situation is for the San Pedro River, with Fort Huachuca as the main offender,” said Robin Silver, co-founder of the Center for Biological Diversity. “Inaction in every direction is sucking the San Pedro dry and endangering the animals and plants that depend on this treasured river to survive.”

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.

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. A 2023 court ruling quantified those water rights and required that groundwater levels be maintained at nine monitoring wells.

The latest USGS measurements taken in June at four of the monitoring wells showed levels below the mandatory requirements. Mandatory water levels and most current levels for the monitoring wells are:

• Palominas #5, 4,244.1 feet (mandatory level 4,246.1 feet)
• Cottonwood, 4,067.13 feet (mandatory level 4,070.7 feet)
• Boquillas #2, 3,878.28 feet (mandatory level 3,879.05 feet)
• Summers, 3,715.48 feet (mandatory level 3,717.3)

At Lewis Springs, the mandatory water level is 4,040.9 feet, with the latest level 4,041.39 and reflecting a downward trend. Two monitoring well levels are above minimum requirements and no information is yet available for the other two.

The U.S. Army’s Fort Huachuca continues to grow 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 Fort.

Gov. Katie Hobbs’ administration has refused to create an active management area to preserve groundwater in the Upper San Pedro Basin or revoke a 100-year designation of water adequacy for a 7,000-home development in Sierra Vista that lacks enough water to support it.

“Our leaders are leaving the San Pedro River unprotected and future homeowners vulnerable to their taps running dry, while these well levels continue to drop,” said Silver. “There’s still time to save this vibrant ecosystem, but people have to stop pretending there’s an endless supply of water. This new information shows it’s slipping away.”

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.