SALEM — Opponents of a large poultry operation in Oregon’s Willamette Valley claim state regulators unlawfully permitted the proposed facility without requiring sufficient protections against water pollution.

A neighboring farmer and several nonprofit organizations have filed a court petition seeking to overturn the state Department of Agriculture’s approval of a “confined animal feeding operation permit” for J-S Ranch in Scio.

The proposed poultry operation’s owner, Eric Simon, said the facility was engineered to shield water from any pollution and those plans have already been vetted by state attorneys during the administrative process.

“I definitely don’t feel we’re doing anything wrong and we’ve got the law on our side,” Simon said.

A representative of the state Department of Agriculture said the agency hasn’t yet read the filing but will be discussing the matter with the Department of Justice.

According to the petition for judicial review, permit conditions imposed on the CAFO, which will generate about 4,500 tons of chicken manure annually, are inadequate to prevent waste from reaching a nearby waterway.

“Any flooding on the property will spread contamination across the local area and into the adjacent North Santiam River,” the petition said.

Stormwater runoff is likely to exceed the capacity of storage ponds on the property, endangering surface water, while nitrogen leaching from the barns and reservoirs threatens groundwater, the petition said.

Fans in the 11 poultry barns will also blow dust from chicken litter into the air, which will eventually settle and deposit ammonia into the river, the petition alleges.

These problems have rendered the CAFO permit inconsistent with the Clean Water Act, as well as state regulations intended to prevent pollution in the North Santiam River Subbasin, the petition said.

Because the ODA lacked substantial evidence that permit conditions will prevent water pollution, the court should reverse or modify the decision, the petition said.

The petitioners — Christina Eastman, Farmers Against Foster Farms, Friends of Family Farmers and Willamette Riverkeeper — also seek compensation for their litigation costs.

Eric Simon, the facility’s owner, said he’s been raising poultry for 20 years with a clean environmental record and believes the permit has a “really strong case” in court.

Manure will be quickly be removed and sold as fertilizer while the small amount kept on-site will be stored indoors, protecting it from the rain, he said.

The chicken litter is also treated with a substance that prevents ammonia from volatilizing, guarding against pollution while enhancing the nitrogen content of the fertilizer, Simon said.

“What they’re saying is the same old stuff and it just isn’t true,” he said.