Bill Richardson, running for president, lost a couple million potential votes around the Great Lakes this month by mentioning the Idea That Must Not Be Named. The New Mexico governor told a Las Vegas newspaper that there’s lots of water up north — “states like Wisconsin are awash in water,” he said — and that it could get shared.

This wouldn’t be so panic-inducing if the Great Lakes’ supposed friends could tell the difference between New Mexico and their own neighbors.

Anyhow, Mr. Richardson gave form to the bogeyman Midwesterners have feared for years — the thirsty westerner. He might as well have drawn a pentagram on the Indiana Dunes and said he was going to pull open Satan’s own drain plug. Editorialists raged. Fear got mongered. “It’s a wake-up call for us,” the director of the Michigan League of Conservation Voters, Lisa Wozniak, said.

The Great Lakes are already in biological chaos, their fisheries in deep trouble from weird invasive species. They’re unusually low, and lakes Huron and Michigan, it turns out, have been lowered further by a botched dredging of their outlet in the 1960s. Amid all this, the wake-up call is supposed to be the engineering and economic improbability of piping water over 1,000 miles of prairie, desert, and Rocky Mountains?

Yet that is what gets adrenaline flowing. It comes from seeing population, power, money, and the nation’s whole center of gravity flow away from the cities along the Great Lakes to warmer, dryer places. All we have left is water.

To keep it, Great Lakes governors a few years ago worked out what’s called the Great Lakes Compact. Existing rules give any of the eight governors a veto over diversions — sending water outside the lakes’ drainage basins — but people suspect this arbitrary system would lose in court. The compact supposedly sets conditions by which governors say no or yes: Only to communities right outside the watershed, only if the wastewater comes back, so on.

To be law, the compact must be ratified by each of the eight states. It’s stalled in two legislatures particularly — Wisconsin and Ohio. By no coincidence at all, these are states where the thin blue watershed line runs near major metropolises. Compact critics say the pact is vague enough that any governor still will hold an arbitrary veto over water for any other state’s towns right outside the basin.

The compact isn’t a problem in Michigan, almost entirely within the lakes’ basins, meaning plentiful water for all. No problem in Illinois, either, since it’s already exempt and has been ever since engineers reversed the Chicago River to flow out of Lake Michigan. Thus, subdivisions spring up well away from the lake, boasting of ample, tasty Lake Michigan water instead of wells. All that water will eventually be flushed down the Illinois River into the Mississippi — the very flow the compact would bar anywhere else.

The compact is a huge problem in Milwaukee’s western suburbs. The watershed line lies only four miles or so past the western extremity of the city itself, and much of the area’s growth is in suburbs where municipal wells are contaminated with radium and are becoming unusable. Two suburbs, Waukesha and New Berlin, have already asked to buy lake water. Governor Granholm of Michigan has made it plain she’d veto any such requests.

She’d find backers in Wisconsin. Elsewhere, the Great Lakes boundary runs amid farms and trees. Because it cleaves city and suburb in Milwaukee, lake water here has become a proxy fight for antipathy toward suburbs generally.

Waukesha, an old, pretty city enveloped by the metropolitan frontier, has banned daytime lawn sprinkling, put conservation in its building code, and actually is seeing declining water use despite rapid population growth. Doesn’t matter: Local environmentalists still decry selling it water, saying it’ll set a precedent and next thing you know, Phoenix will be sucking up the lake.

Others openly snark that suburbanites whose wells become unusable can simply move to Milwaukee proper if they want water. At least several public officials have hinted that water will be forthcoming only if suburbs agree to build Milwaukee a light-rail system.

Wisconsin lawmakers had set up a committee to ponder the compact. It fell apart, chiefly over just how hard the state would push to ensure lake water could go to Milwaukee suburbs. Thus, this irony: Those people most worked up by Mr. Richardson’s talk of tapping the lakes may see their shield collapse because environmentalists in Wisconsin cannot distinguish between suburbs within flushing distance of the lake and the desert Southwest.

Waukesha talks of returning any purchased lake water via a manmade wetland to further cleanse its treated sewage. It’s inconceivable that Santa Fe would ever pump any used water back to keep Lake Michigan topped off. Yet, yammering about “sprawl,” some Milwaukeeans treat Waukesha as if it were as remote as Santa Fe. Thus, one of the state’s most politically powerful areas, home base of the state’s Republican Party, is made to feel that this law to protect the Great Lakes is contrary to its own survival.

What’s more, by using water as a weapon, environmentalists would stifle one of the growth spots of the Great Lakes region. Bad move. Mr. Richardson’s talk of a “national water policy” wouldn’t have legs if Great Lakes cities were attracting people, wealth, and political power at anything close to the rate of the thirsty Sunbelt. They’re not. Say what you will about making Texans move back, but trying to dry up suburbs exhibits exactly the inhospitable attitude toward growth that sent the Rust Belt’s momentum south to begin with.

Nothing will better fend off predators of the Great Lakes than having some more allies with money living nearby. Yet the lakes’ own self-declared defenders don’t recognize those future allies, one county to the west.

If Mr. Richardson scares us, we deserve it.

Mr. McIlheran is a columnist for the Milwaukee Journal Sentinel.