Idaho and Nevada are among several states positioning themselves to attract California egg producers if an animal care law drives out big egg farms, including producers in North San Diego County.

California voters in 2008 approved Proposition 2, banning cramped cages for laying hens by 2015. But the proposition lacked specifications for what would be required, said Eric Larson, executive director of the San Diego County Farm Bureau.

Neither Idaho nor Nevada, where officials are aggressively courting the Golden State egg industry, have restrictions on "battery cages" that leave chickens little room to spread their wings.

Idaho state Sen. Tim Corder, a Republican, has no desire to change that in his state. Industry should decide, Corder insists.

Still, the Idaho Senate Agriculture Committee chairman does want to revamp rules governing where and how giant poultry farms are operated to skirt pitfalls that accompanied explosive growth of Idaho's dairy industry. His state went from 180,000 cows in 1990 to 530,000 in 2009 to become the third-biggest milk producer after California and Wisconsin, but the arrival of mega-dairies caught regulators flat-footed and prompted environmentalists to call foul.

"The time when agriculture can sweep in and do whatever it wants and nobody will say anything about it until it's too late, that time is past," Corder said. "If we're going to do this, let's do it right from the start."

Corder, whose poultry plan is due for discussion in the Idaho Capitol this week, isn't alone in thinking California egg producers may come calling.

Following Prop 2, Nevada officials want to poach their share of a possible egg exodus.

"We've contacted various members of poultry associations, especially in the California market," said Kathy Johnson, Pershing County's economic development director. "We're not trying to play predator. We're simply offering an option."

A group of California egg producers already has met with Nevada officials eager to persuade them to move their operations to a location near Reno.

Moving an egg farm though is an expensive proposition, growers note.

One University of California-funded study before the 2008 ballot measure concluded costs would rise 20 percent, including equipment investments and use of more feed, and result in almost all egg production leaving after six years. Only 5 percent of U.S. egg production comes from non-caged hens.

California is the nation's fifth-largest egg producer, with 5 billion eggs annually. Iowa is tops, with 14.3 billion. Idaho and Nevada aren't even close.

So far, Debbie Murdock, executive director of the Association of California Egg Farmers, hasn't heard of any impending relocations to Idaho, Nevada or elsewhere.

Still, Prop 2 has her members concerned.

"We have 20 million hens in this state," Murdock said. "It's a huge expense for us to have to move. It's a huge expense for us to change our housing. A move like this, especially in this economic climate, can be very scary."

The Humane Society of the United States, which backed Prop 2, says the industry is trying to frighten other states from pursuing similar measures. And similar measures are coming: Michigan's governor signed legislation in October requiring more room for hens, while Ohio plans a vote next November.

Regardless of the votes, a big egg rancher in North San Diego County said if the legislation ends up requiring bigger new cages, it is likely to force them to either close of leave the state. Ryan Armstrong, president of Armstrong Egg Farm in Valley Center, said it could cost up to $15 million to acquire additional land and more space for the half a million chickens now living in cages at the farm. An additional 45,000 chickens live in "free-range" habitats at Armstrong, but demand has fallen for such eggs, he said, and it costs twice as much to produce cage-free eggs.

Egg production in Riverside County is centered in the Coachella Valley.

Even without new laws, retailers such as Bentonville, Ark.-based Wal-Mart Stores Inc. are independently demanding that suppliers treat their chickens humanely, said Paul Shapiro, the Humane Society's factory farm campaign director.

"You see a shift in the marketplace, not because they are compelled to do so by law, but because they don't want to be selling a product that's criminally cruel to produce," Shapiro said.

Pam Juker, an Idaho Department of Agriculture chief of staff, concedes Idaho regulators struggled to keep pace when big dairies began targeting cheap Idaho land to build 5,000-cow dairies two decades ago. Air and water pollution concerns emerged, as did a backlash over smells. Today, a legal stink lingers between the Idaho Dairymen's Association and counties over power to regulate feedlots.

"The laws and rules had to be developed alongside the industry growth," Juker said. "With this (Corder's) proposed legislation, it will help to have the regulatory structure in place before a new industry settles in."

The Idaho Conservation League has highlighted nitrate threats to southern Idaho groundwater from millions of tons of dairy manure. Justin Hayes, a spokesman in Boise, said poorly regulated poultry farms could make things worse. He hasn't endorsed Corder's bill.

"There's not currently enough oversight of where we place dairy manure," Hayes said.

Even if California poultry operations don't find Idaho, Corder is sure others will.

Des Moines, Iowa-based Hy-Line North America last year opened a new facility in Burley, in southern Idaho, that hatches million of hens to be shipped elsewhere. And last month, commissioners there approved zoning changes to allow a broiler chicken plant to house up to 4 million birds. One thousand employees would process some 13,000 birds an hour.

"They aren't just coming," Corder said. "They're already here."

Staff writer Jeff Rowe contributed to this report.