Water-law reform is something nearly every New Mexican knows is overdue — but the mere thought of action in that vital area has moved at a snail's pace for the better part of a century.

So imagine the shock over a still-small ruling last week in the southwest part of our state:

Sixth District Judge J.C. Robinson said that, as far as Grant, Hidalgo and Luna counties are concerned, the state law allowing wholesale drilling of domestic wells is unconstitutional.

The judge was dealing with a case filed by Horace and Jo Bounds, who argued that four dozen wells punched into the ground near their irrigated farm were drying up the place — and infringing on their water rights, which go back to the 19th century.

The wells were to supply water to houses near the Upper Mimbres River. Permits to drill them have been seen as some kind of basic homeowners' right; put in your application with the State Engineer's Office, which is in charge of water in New Mexico, and the folks there have to issue your permit.

Santa Fe and other local governments lately have been putting their feet down on this tradition too long treated as supreme law, using home rule to limit domestic wells where there's municipal water available. But out in the boonies, the water rush goes on. After all, families have got to have water, don't they?

Well, yes — but what're they doing turning rural areas into ranchettes and bedroom communities? Especially if everybody there is putting a straw into the same soda bottle?

It doesn't work for the Bounds and other irrigators to sit around waiting until they're out of water, said the judge. "When the water is gone, it will be too late."

That, he said, is a violation of due process that senior rights holders have coming. The State Engineer, he declared, can't treat the domestic-well process differently than other types of water rights applications.

John D'Antonio serves as State Engineer in Gov. Bill Richardson's administration. He's seen a decision like this coming for several years — and he's urged the state Legislature to reform the domestic-well law. Some of our state's more respected environmentalists also have sought reforms, largely in vain; land-development lobbyists like things the way they are — and they've got the bucks it takes to influence the senators and representatives who count.

Robinson's ruling applies only to those three counties. There, sensibly enough, applications to drill domestic wells could have to be advertised in local newspapers — and would be subject to protest.

If that were to happen statewide, the State Engineer's Office would face huge new waves of paperwork. But it's better than the ongoing assault on New Mexico's water supply, which has more of it spoken for than there really is. That office, clearly, needs more money.

This case is only one blow to D'Antonio and his office. Sitting in the state Court of Appeals is another water case — and a friend-of-the-court brief calling into question nearly every basic premise about water law. More about that from this corner in a few days.

Legislative good-ol'-boys dismiss the Mimbres decision, guessing that other ol' boys in the judicial system will reverse Robinson's decision. More responsible members, including Senator-to-be Peter Wirth, see it as the wake-up call that it is.