TUCSON, Ariz. – The Center for Biological Diversity sued the U.S. Bureau of Land Management and Fish and Wildlife Service today for failing to protect the endangered Southwestern willow flycatcher, threatened northern Mexican garter snake and threatened western yellow-billed cuckoo from illegal livestock grazing along the Big Sandy River in western Arizona.

“Throughout the Southwest the Bureau of Land Management’s chronic failure to control illegal livestock grazing turns streams and streamside habitats into trampled cesspools, pushing endangered species closer to extinction,” said Chris Bugbee, Southwest conservation advocate at the Center for Biological Diversity. “The Big Sandy River is just the latest example in a pattern of neglect. This lawsuit aims to force federal agencies to do their jobs, fix the problem and save this ecosystem.”

In 2023 and 2024, Center field biologists documented unauthorized cattle grazing and associated damage to the species’ designated critical habitat across three public-lands grazing allotments along the Big Sandy River. Damage was significant on six of seven river miles surveyed and included destruction of streamside plants, shrubs and trees, trampling of the river bottom and banks, and cattle feces in the river. Surveys showed limited damage from wild burros, whose local population the BLM has already begun to reduce.

Today’s lawsuit follows the BLM’s failure to acknowledge or remedy the problems after notification by the Center in late 2023.

The Big Sandy River flows south from the western flanks of the Santa Maria and Arrastra mountains, joining the Santa Maria River in southern Mohave County to form the Bill Williams River. Critical habitat at risk includes riparian forest upstream of the river’s confluence with the Santa Maria.

Field surveys in recent years have documented chronic and severe damage from unlawful livestock grazing to endangered species habitat along hundreds of miles of streams, rivers and tributaries on public lands in Arizona and New Mexico. A recent Center report showed that cattle grazing has caused moderate to significant damage across a majority of the critical habitat designated for the threatened western yellow-billed cuckoo in both states.

Litigation and agreements resulting from some of those surveys required federal agencies to monitor and remove livestock from riparian critical habitat. Agency compliance with those agreements has been mixed, with some areas seeing livestock removed from critical habitat, while in other areas unauthorized grazing persists.

Up to 75% of Arizona’s wildlife species depend on riparian areas, although these areas make up less than 1% of state land. During the 20th century most of Arizona’s low-elevation riparian habitats were destroyed by human activities, including livestock grazing.

Across the desert Southwest, livestock grazing harms threatened and endangered wildlife and is the primary driver of riparian ecosystem degradation and species imperilment. Removing livestock from riparian areas is critical to curbing the extinction crisis in the Southwest.