BOISE, Idaho (AP) — Livestock groups that lost a recent Idaho Supreme Court decision asked lawmakers Thursday to come to their defense by scaling back local authority over large dairies with thousands of cows and tons of manure.

Milk Producers of Idaho lobbyist Ken McClure told the Senate Agricultural Affairs Committee that Idaho should limit counties to matters involving the location of dairies and forbid them from passing stricter air and water quality standards than those already on Idaho's books.

Counties oppose the proposal, arguing existing environmental laws have done little to address the cumulative effects of large dairies that have helped make Idaho the nation's third biggest milk-producing state but also led to pollution concerns.

"We're not shutting the doors" to dairies, said Tom Faulkner, a Gooding County commissioner. "We're just saying we want to protect the existing resources of the county."

On Feb. 1, state Supreme Court justices ruled against the dairy association and the Idaho Cattle Association, deciding state water quality laws did nothing to pre-empt Gooding County from passing its own regulations. The court also upheld a lower court decision that the county's ordinance wasn't arbitrary and capricious.

Another legislative hearing is set for Monday.

A tentative version of the industry-backed proposal says local governments would be "pre-empted from imposing requirements on dairy farms or on the application of dairy nutrients for the purpose of protecting air and water quality."

Gooding County in southern Idaho has become Idaho's epicenter for dairy activity, where cows are the top industry. The county produced about 240 million pounds of milk products in 2008.

At issue in the court case was the county's 2007 ordinance, which includes provisions that limiting big feedlots from being within a mile of the Snake River or Malad River canyons and imposing strict, five-cow-per-acre limits.

With the measure, Faulkner and other commissioners were responding to increasing concerns among residents that the accumulation of dairies was resulting in too much manure. There were also increasing complaints about contaminated wells, odors, pests, dust and other airborne contaminants.

The county said a soil sampling of agricultural fields in 2006 showed 88 percent exceeded the maximum allowable phosphorus levels set by the state.

McClure, whose Boise-based law firm represented the industry groups on the losing side of the state Supreme Court decision, contends it's the state and federal government, under the Clean Water Act and the Clean Air Act, that should have final say in determining if a proposed new dairy will have harmful effects on the environment.

"At some point, you have to look at this as, when is enough enough on the regulatory front?" McClure said.

Environmental groups have sided with the counties, saying problems will only increase if the dairy industry is given its way.

"A big part of the solution would be if the state was doing a better job of regulating, then the county governments wouldn't have to," said Courtney Washburn, of the Idaho Conservation League in Boise.

Copyright 2010 The Associated Press.