TUCSON, Ariz.— A new survey shows cow grazing has significantly damaged almost all of nearly 42 river miles surveyed in the San Pedro Riparian Conservation Area, putting the area’s remarkable ecosystem and endangered species at risk.

The survey, released today by the Center for Biological Diversity, documents 39 miles of significantly cow-damaged streamside habitat along the San Pedro River, Babocomari River, and St. David Cienega within the U.S. Bureau of Land Management’s San Pedro Riparian National Conservation Area. Moderate damage was documented on an additional 1.82 miles of the total 41.9 miles surveyed this past week by Center biologists.

The survey found widespread damage — including denuded vegetation, trampling and cow feces — along the San Pedro River, where cows are prohibited year-round, and along the Babocomari River, where the BLM allows cattle grazing only during the winter.

“We’ve essentially lost the entire San Pedro River understory because of grazing promoted and facilitated by cow-worshipping, rancher-fearing BLM employees,” said Center cofounder Robin Silver. “Management of this fragile ecological treasure should be transferred to the National Park Service.”

The Center’s survey follows 133 complaints of cow trespassing and habitat damage filed by the Center with BLM the over the past three years. In an August 2022 agreement following a 2021 lawsuit, BLM officials promised to remove livestock from riparian areas in the conservation area where grazing is prohibited.

However, since then the Center has documented and filed 81 trespass cow complaints, including documentation in November 2021 that cow grazing had destroyed the largest core population of endangered Huachuca water umbel.

In September 2021 the conservation area’s manager, Scott Feldhausen, admitted that he has not been rounding up the cows because of “fear of violence by local ranchers” to his staff.

“It’s impossible to settle any litigation with BLM employees who are simply not motivated to comply with the law,” said Silver. “It’s obvious we’ll have to go back to court to save the river from this devastating cow grazing.”

Last week the Bureau announced its intent to continue cow grazing in the San Pedro conservation area despite Congress’ direction to protect it.

The San Pedro Riparian National Conservation Area was the nation’s first, created by Congress in 1988. It includes more than 46 miles of the San Pedro and Babocomari rivers and nearly 55,000 acres of riparian areas and uplands. It is home to four of the rarest habitat types in the Southwest: cottonwood/willow forests, marshlands, grasslands and mesquite bosques.

More than 400 birds, 50 species of reptiles and amphibians, and 80 species of mammals are found in the conservation area, making it a world-renowned biodiversity hotspot.

The San Pedro River is 1 of 3 official North American Important Bird Areas, as designated by the Canada-based, trilateral Commission for Environmental Cooperation. In 1993 Life Magazine named it as one of “America’s Last Great Places” quoting the conservation area’s then-manager Greg Yuncevich: “As soon as we acquired it, we eliminated grazing, sand and gravel operations and off-highway vehicle use — the kinds of things that kept the river from being able to heal itself.”

In addition to the Huachuca water umbel, other endangered species dependent on the San Pedro for survival and recovery include southwestern willow flycatchers, ocelots, jaguars, desert pupfish, Gila topminnows, Northern Mexican garter snakes and Arizona eryngo.

In a March 2018 letter to the Bureau of Land Management, 21 scientists urged the agency to exclude livestock grazing from the conservation area. Allowing livestock grazing jeopardizes the area’s many aquatic and riparian species and its critically important role as an ecological reference site, they wrote.