Cattle grazing and clean water can coexist on national forest lands, according to research by the University of California, Davis. The study, published in the journal PLOS ONE, is the most comprehensive examination of water quality on National Forest public grazing lands to date.

"There's been a lot of concern about public lands and water quality, especially with cattle grazing," said lead author Leslie Roche, a postdoctoral scholar in the UC Davis Department of Plant Sciences. "We're able to show that livestock grazing, public recreation and the provisioning of clean water can be compatible goals."

Roughly 1.8 million livestock graze on national forest lands in the western United States each year, the study said. In California, 500 active grazing allotments（分配） support 97,000 livestock across 8 million acres on 17 national forests.

"With an annual recreating population of over 26 million, California's national forests are at the crossroad of a growing debate about the compatibility of livestock grazing with other activities dependent upon clean, safe water," the study's authors write.

"We often hear that livestock production isn't compatible with environmental goals," said principal investigator Kenneth Tate, a Cooperative Extension specialist in the UC Davis Department of Plant Sciences. "This helps to show that's not absolutely true. There is no real evidence that we're creating hot spots of human health risk with livestock grazing in these areas."

The study was conducted in 2011, during the grazing and recreation season of June through November. Nearly 40 UC Davis researchers, ranchers, U.S. Department of Agriculture Forest Service staff and environmental stakeholders went out by foot and on horseback, hiking across meadows, along campsites, and down ravines to collect 743 water samples from 155 sites across five national forests in northern California.

These areas stretched from Klamath National Forest to Plumas, Tahoe, Stanislaus, and Shasta-Trinity national forests. They included key cattle grazing areas, recreational lands and places where neither cattle nor humans tend to wander.