Seemingly from out of nowhere, New Mexico has emerged as a major dairy state: 350,000 cows crowd scores of modern high-yield farms, most of them in the southeastern part of our state, making us the nation's No. 7 milk producer.

It's now our state's leading agricultural enterprise, with a $2 billion-a-year economic impact, and most of its growth has taken place since the mid-'90s.

But for all the bucolic aspects of dairying, even in today's tightly managed, relatively clean conditions, it carries a high environmental price: Cows here excrete 5 million gallons of feces every day; nitrate-rich stuff in quantities too great to convert readily into fertilizer. It leaches into the state's groundwater, and it's become a major pollutant.

Farmers and community leaders in the Midwest, where dairies long thrived, have known for years that concentrated animal feeding operations can be health hazards. Some counties in dairy-famous states called a halt to expansion — and seeing the handwriting on the silo walls, dairy-industry executives began casting about for, uh, more friendly locations.

So it was more than mere coincidence that our state became a budding Wisconsin; and while many of the operations have shown a willingness to be good environmental neighbors, some are balking at efforts by the state Water Quality Control Commission to impose rules drawn up by the Environment Department.

Hearings began yesterday at the Capitol on those regulations, which aren't likely to be in effect for months — but already industry spokespeople say they go too far, especially when it comes to lining wastewater lagoons with impermeable plastics. Underground layers of clay down in dairy country, they say, protect the groundwater.

State water-quality officials told the New Mexico Independent that the clay isn't stopping the seepage; that synthetic liners offer the protection that's needed.

They're hugely expensive, says the dairy-producers' association — and regulations requiring them could run a third to half the dairies out of our state.

The industry has a bad economy on its side: States once strict about the environment are having second thoughts about some of their rules.

But New Mexico — where water's always in short supply? Can we afford to contaminate great amounts of it?

The proposed rules would apply only to ponds within 50 feet of groundwater; they're aimed at new ones — or those that are already polluters. But that's
65 percent of the dairies; thus the push-back now that the state seeks serious rules.

Maybe the economy will be a factor in delaying, or slowly phasing in, some of the more onerous of the rules — yet as the dairy people recognized in lobbying last year for state regulation, their industry, and the state that's their home, have got to have them.