Cattle grazing and clean water can coexist on national forest lands, according to new research by the University of California-Davis (UC-Davis).
The study, published June 27 in the journal PLOS ONE, is the most comprehensive examination of water quality on national forest public grazing lands to date, an announcement said.
"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 U.S. each year, the study found. In California, 500 active grazing allotments support 97,000 livestock across 8 million acres on 17 national forests.
"With an annual recreating population of more than 26 million (people), California's national forests are at the crossroads of a growing debate about the compatibility of livestock grazing with other activities dependent upon clean, safe water," the researchers wrote.
"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 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 that runs from 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 included the Klamath, Plumas, Tahoe, Stanislaus and Shasta-Trinity national forests. Samples were taken from key cattle grazing areas, recreational lands and places where neither cattle nor people tend to visit.
The UC-Davis researchers analyzed the water samples for microbial and nutrient pollution, including fecal indicator bacteria, fecal coliform, Escherichia coli, nitrogen and phosphorous.
They found that recreational sites were the cleanest, with the lowest levels of fecal indicator bacteria. They found no significant differences in fecal indicator bacteria between grazing lands and areas without recreation or grazing, the announcement pointed out. Overall, 83% of all sample sites and 95% of all water samples collected were below U.S. Environmental Protection Agency benchmarks for human health.
The researchers noted that several regional regulatory programs use different water quality standards for fecal bacteria. For instance, most of the study's sample sites would exceed levels set by a more restrictive standard based on fecal coliform concentrations. However, EPA has determined that E. coli are better indicators of fecal contamination and provide the most accurate assessment of water quality conditions and human health risks, UC-Davis said.
The study also found that all nutrient concentrations were at or below background levels, and no samples exceeded concentrations of ecological or human health concern.
The study was funded by the USDA Forest Service, Region 5.
The report is available online at www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0068127.