University of California

Grazing Impacts


Sunol Valley, CA – Here’s a story about how people used cows to nearly ruin some precious watershed lands, and how they came to their senses to use cows to preserve it.

A little-known fact: San Franciscans obtain15 percent of their water from 40,000 acres of oak-dotted grasslands rolling across the Alameda – Santa Clara county line.

The San Francisco Public Utilities Commission (SFPUC) bought the Alameda watershed in 1934 from the Spring Valley Water Company to augment its water supplies from Hetch Hetchy Reservoir in the Sierra.

Most of the land – 34,000 acres – was leased to ranchers who grazed cattle and farmers who raised crops that needed no irrigation.

“The commission operated the ag lands program in a low-key manner until 1969,” drawls Tim Koopmann, a SFPUC watershed resource specialist, and third generation cattle rancher whose lands abut the watershed. “Negotiations were done over a cup of coffee at the kitchen table. The lessees took care of the property just as well as their own.”

Then, in 1969, a SFPUC attorney must have seen dollar signs floating above the rolling hills. He put the leases out to open auction. Most of the leases went to people who weren’t ranchers, says Koopmann – a mortician, a car dealer, a man who owned a garbage company. Partly because of many of the bidders’ ignorance, as well as an open bar at the auction, they paid too much for the leases.

“Once folks realized that they were paying more for the leases than they should, not only did they bring more cattle in, they did not maintain any of the infrastructure. So it was a disaster,” says Koopmann. “Many of us in the ag community sat and watched the abuses that were going on for about 20 years.”

By 1992, the SFPUC noticed lands weary with overgrazing, and began worrying about water quality. They proposed some management changes. But the big push came in 1997, when a SFPUC member whose constituency included San Franciscans with compromised immune systems expressed concern about pathogens in the water. He proposed all grazing be stopped, because he thought that cows were defecating cryptosporidium into or near streams.

When University of California researchers Rob Atwell and Ken Tate analyzed the water, they found no problems with cryptosporidium. But, in the process, the SFPUC decided to re-adjust its grazing program to one whose goal was watershed health, not increasing revenue.

About the same time, Sheila Barry, a natural resources/livestock advisor at UC’s Cooperative Extension, and Keith Gunther, a consultant who’d been working with the Nature Conservancy, were developing a comprehensive Web site for landowners to develop and evaluate grazing management plans.

As they wrote in their introduction on their Web site (“Understanding Livestock Grazing Impacts”): “Unfortunately, livestock grazing is often evaluated as an either/or situation, either good or bad. Discussions that compare only the extremes of no livestock use to ecologically damaging livestock use overlook the large amount of scientific information available that describes the positive environmental impacts that can be accomplished when livestock are managed to consider season of use, grazing intensity and livestock class.”

Barry worked with Koopmann to develop a plan for the SFPUC’s Alameda watershed. Now, says Koopmann, the PUC evaluates all lease areas in terms of soil type, topography, and basic exposure to determine a standard cattle-stocking rate that will reduce the fire risk that occurs when grasslands grow wild, but still protect the soils from erosion and provide adequate habitat for the resident songbirds, tiger salamanders, black tail deer, and tule elk. Light to medium grazing also keeps the serious invasive plants -- star thistle and coyote brush -- in check.

“What we tell the lessees is: ‘Here’s your base stocking rate. If we have timely rains and temps that provide more forage, then there’s opportunity to bring more cattle in. if it’s less than average, then cattle need to be removed,’” says Koopmann.

In addition, all lessees must:

  • submit a land-use proposal, prove their financial health, and include a history of their operations to qualify for a personal interview with a five-person committee;


  • submit a herd health plan every year;
  • have land elsewhere, so that in case of emergency such as wildfire or severe drought, they have a place to move the cattle;


  • make sure all calves are born by the end of October, so that there’s no risk of cryptosporidium contamination during the peak rainy season. Researcher Atwell had found that calves under the age of four months could harbor cryptosporidium.

The SFPUC has also improved fencing, corrals, and installed a series of solar-powered water systems to distribute water to upland areas, “to keep the cattle from camping in the creeks,” and causing erosion, says Koopmann.

The approach and content that Barry and Gunther HOW MANY OTHER AUTHORS – THEIR NAMES? developed has recently finished a long peer-review process. The Web site, partly funded by RREA, was recently officially launched and Barry is starting to get the word out at meetings such as the Society of Range Management.

Much of the site’s content isn’t new, says Barry. But what she and Gunther have done is to put information that’s difficult to find or access into a format that is easy to use and to understand. The site walks people through planning and concept, helps them identify indicator species and create an impacts analysis worksheet, and shows them how to monitor changes.

The Web site covers three habitat types unique to California: blue-oak woodland, valley grasslands and coastal prairie. Gunther and Barry plan to add more.

Already, a few organizations are using the Web site: a Fremont homeowners association that wants to control fire risk in its open space, the East Bay Regional Park System, and people who are managing an 11-acre area of the Watsonville Slough.

The site came about because Barry, through her work with public agencies, realized there was a dire need for a holistic tool “that didn’t just show impacts of grazing on vegetation and wildlife, but also economic and social values,” she says.

“There’s still a lot of misunderstanding between public agencies and grazing lessees about what it takes to run their businesses,” explains Barry. “Sometimes public agencies ratchet up the management requirements based on perception, without any science behind it. They were having a huge impact on lessees without having any impact on the land. It was really clear that we needed a tool that could help people figure all this out, to see the tradeoffs, and to understand that there wasn’t some perfect solution.”

To use the tools on the Web site, explains Barry, “you have to be clear about what your goals are. That’s really difficult with some public agencies. With water districts, it’s easy – water is their first goal. But open space or park districts are a lot more foggy – their missions don’t guide them clearly enough. It often depends on if the staff is recreation or wildlife oriented. The hope is that this tool will help them figure out what their goals are before they address grazing.”

by Jane Ellen Stevens
June 2006

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