Organic dairy farmers greeted proposed legislation to use treated wastewater for livestock consumption with skepticism Thursday, saying it risks the health of their animals and could jeopardize their businesses.

"I'm not going to risk our animals or our customers to an idea that's not tested," said Albert Straus, president of Straus Family Creamery in Marshall.

Assemblyman Marc Levine, D-San Rafael, authored AB 2071 ostensibly to provide drought relief to California ranchers as supplies of potable water dwindle from lack of rain. But Levine mainly heard doubts about his proposal at a public hearing Thursday at Petaluma City Hall.

Straus spoke for many farmers in attendance when he said he felt his cows would be used as "guinea pigs" to test whether treated wastewater is safe for consumption.

Petaluma dairyman George McClelland said recycled water "might be a great thing." But he said he's not inclined to let his cows drink it.

The risk was too much for his dairy and his family, McClelland said. "We've been dairying since 1938," he said.

McClelland was on the panel of farmers, veterinarians, water resource managers and public health representatives invited to speak Thursday.

Advocates for greater use of treated wastewater view it as an untapped source of drought relief for California's farmers, who are staring down the possibility of losing animals if enough rain doesn't materialize between now and summer.

Some farmers already use recycled water for livestock consumption, including operations in Sonoma County. Under a 25-year-old arrangement, the city of Santa Rosa has not restricted about 70 ranchers who are linked to its water distribution system from using treated wastewater for livestock consumption, with the exception of animals producing milk.

That points to widespread confusion over whether current regulations already allow for what Levine is seeking with the legislation. The state's public health agency and regional water quality control boards have regulations pertaining to recycled water, but none that specifically address using it as drinking water for animals. Some water providers have interpreted that to mean the practice is allowed.

"Let us know what the heck the rules are so we can support ranchers and do the right thing in our communities," said Chris DeGabriele, general manager of the North Marin Water District.

Levine's bill would require state public health officials to approve the use of recycled water for pasture animals by 2016 unless officials determine that doing so would pose health risks, in which case, the state would be required to establish uniform standards, such as additional treatment of the water before it could be used.

California Department of Food and Agriculture regulations state that water supplies in milk houses and dairy barns be of "safe and sanitary quality" and conform to the bacterial standards for public supplies of drinking water.

It's unclear whether treated wastewater would meet those standards, said Annette Jones, director of the state agency's Animal Health and Food Safety Services Division.

She said she would be most concerned about giving the water to dairy cows, noting that 87 percent of milk is water. "It's not really clear to me what the risks really are," she said.

Treated wastewater could contain levels of antibiotic-resistant bacteria and hormones that pose a risk to animals, said James Cullor, professor of population health and reproduction at the School of Veterinary Medicine at UC Davis. He said there haven't been any long-term studies to draw conclusions. His recommendation was that recycled water be used only for emergencies.

Cotati veterinarian Gene Harlan said even if the water was deemed safe for animals, organic farmers still risk a backlash from the public by using it.

"There's a reason why this area has become 90 percent organic (dairies)," Harlan said. "That's what the consumer is asking for."

Petaluma Councilman Mike Healy, who sparked the legislative effort, said it's not the city's intent to require any farmers to use recycled water for their animals. But he warned that the city's current water allocation for agricultural customers "may not be sustainable."

The city currently is dispensing potable water for agricultural purposes at a rate of about 50,000 gallons a day, or less than 1 percent of its overall daily supply. But that supply could be affected by continued drought conditions and mandated cutbacks.

Levine's bill covers all pasture animals. But he said at the conclusion of Thursday's hearing that giving dairy cows recycled water was "never the intent of any legislation."

Levine said there's "great interest" in furthering research to "ensure the safety of using this water." Asked whether he's comfortable with the research that exists now to recommend what he's proposing with his bill, Levine replied, "I think what we learned today is that it's not clear. We need to do more work to figure that out."

(You can reach Staff Writer Derek Moore at 521-5336 or derek.moore@pressdemocrat.com. On Twitter @deadlinederek.)