One of the quirks of western water law is the variety of ways the different states treat groundwater. In New Mexico, for example, the law recognizes that groundwater and surface water are inextricably linked. This is merely a recognition of hydrological reality. Pump groundwater, and eventually surface water soaks down to replace it, depleting a surface resource.

In Arizona, not so much. The hydrology is the same, but the law says one can drill to one’s heart’s content in one’s own backyard. I’ve heard stories of residents of Tucson, in defiance of high water rates, simply drilling a backyard well.

Now the Bureau of Reclamation is trying to crack down on such drilling along the Colorado River, according to Shaun McKinnon in today’s Arizona Republic:

Hundreds of people who illegally pump water from wells along the lower Colorado River could face a tough choice soon: Pay to acquire rights to the water or turn the spigot off.

The U.S. Bureau of Reclamation, which oversees the river in Arizona, Nevada and California, has proposed new rules that target the well owners, who drain as much as 5 billion gallons of water a year from the Colorado.

Most of the well owners are private citizens who have drilled their wells too close to the river. Instead of pumping groundwater, to which landowners have a right, they are drawing water from the river’s subsurface flow. Well owners must get approval to siphon water from the river’s surface or subsurface.

(Note that the New Mexico picture is not quite as rosy as I painted above, because of a state statute currently in the courts that gave a generous exemption for domestic wells.)