Water has become the 21st-century equivalent of oil, and a plan to divert water from the Great Lakes to surrounding areas is raising questions about the possibility of future water grabs from far-flung water-sparse regions.

While plans to divert water from the Great Lakes basin date back to the early 1900s, modern-day attempts have become increasingly extravagant. In 1982, Congress directed the U.S. Army Corps of Engineers to study the feasibility of using Great Lakes water to irrigate farmland on the Great Plains. (Not so feasible, said the Corps.) Fifteen years later, a businessman in Canada secured a permit from the Ontario Ministry of the Environment to transport 158 million gallons of water each year from Lake Superior to Asia in tanker ships. (He withdrew his proposal in 1998 under pressure from Canadian officials.) And in 2007, New Mexico Governor Bill Richardson, in his presidential bid, suggested piping Great Lakes water to the arid Southwest. (Richardson’s campaign foundered and his trial balloon burst.)

But it was the proposal put forth by the Canadian businessman that especially rattled citizens and set off alarms among officials in the eight states and two provinces that border the Great Lakes, propelling them to devise once and for all a binding binational system that would manage and regulate the largest source of surface freshwater in the world. Over the course of seven years, policy makers, lawyers, and elected officials from each of the Great Lakes states and provinces crafted the Great Lakes-St. Lawrence River Basin Water Resources Compact. Passed by Congress and signed into law in 2008 by President George W. Bush, it was lauded as a model agreement by industries and environmentalists alike.

Notably, throughout the long process, the states and provinces had the Milwaukee suburb of Waukesha, Wisconsin, in mind as an eventual test case for their compact, which is now underway. A massive proposal by Waukesha to “borrow” up to 8.4 million gallons of Lake Michigan water every day (or 3 billion gallons every year) is weeks away from an up-or-down vote by the governors of the Great Lakes states.

Waukesha has had problems with its drinking water since the early 1990s, despite being situated in water-rich southeastern Wisconsin. Due to decades of unrestrained suburban growth, the deep sandstone aquifer that is its primary source of drinking water began to decline, resulting in concentrations of radium in the groundwater that exceeded Environmental Protection Agency standards established by the Clean Drinking Water Act of 1970. After an unsuccessful lawsuit contesting the validity of the EPA’s requirements, leaders of the roughly 70,000-resident city looked to the Great Lakes for a solution.

In eastern Wisconsin, a subcontinental divide marks the boundary of the Great Lakes drainage basin. Rivers and streams east of the divide flow into the Great Lakes. Waukesha, 17 miles west of Lake Michigan, sits just beyond its reach in the Mississippi River basin. The Great Lakes compact expressly prohibits diversions out of the basin. But there are exceptions. Communities that straddle the basin’s boundary line can win diversion rights with little more than state approval. The designers of the compact went further, creating a loophole that allows communities that exist totally outside of the basin—such as Waukesha—a chance at the lakes’ water. If these outlying cities or towns are in a county that straddles the basin boundary, they can apply for diversions as well.

The city of Waukesha, which lies in the straddling county of Waukesha County, formally submitted its application for a diversion in January—13 years after being prodded by a Wisconsin circuit-court order to have in place an alternative drinking-water source that meets EPA regulations for radium by June 2018. If approved, Waukesha would pump water from Lake Michigan to its water-treatment plant. In turn, as required by the compact, it would send the same amount back to the lake in the form of treated wastewater via a series of pipelines and via the winding Root River, which empties in downtown Racine, Wisconsin.

Proponents at a public hearing in February said the diversion is a no-brainer, a concept as uncomplicated as removing a teaspoonful of water from a swimming pool and returning it as clean as ever. The criteria, of course, are more elaborate. According to the compact, water returned to the basin must be equal in quality to the water taken out; diverted water will be allowed only if there is no “reasonable” alternate water supply available; a comprehensive water-conservation program must be in place; and the diversion must not affect the “integrity of the Basin ecosystem.”

Critics cite major flaws in the proposal: Studies by the U.S. Geological Survey show that Waukesha’s deep aquifer is in fact recharging, not declining, calling into question the very need for diverting Lake Michigan water. Although Waukesha treats a sizable portion of its radium-tainted water, critics say it has been slow to try alternative treatment technologies that have been used successfully by adjacent (and rapidly developing) communities. Wastewater released into the Root River—and potentially along Racine’s pristine public beaches—would also likely contain “chemicals of emerging concern,” such as discarded pharmaceuticals and personal-care products, which are not adequately regulated by state or federal governments, said Nicholas Schroeck, the director of the Transnational Environmental Law Clinic at Wayne State University.

Environmentalists argue that the Waukesha clause sets a bad precedent: If approved, it would distort the boundaries of the Great Lakes basin and lead the compact down a dangerous slippery slope. Of the 68 counties that straddle the basin line, some presumably will consider a diversion request, if Waukesha’s plan is approved. John Dickert, the mayor of the lakeside city of Racine, told me he has already received inquiries from two mayors in Arizona regarding the possibility of a Keystone-like pipeline from the desert.

“The battle over water is just beginning,” Dickert said in February. “You’ve already seen it out in California, in Arizona. Our aquifers are drying up around this country. You’re seeing it everywhere.”

On its face, the compact does not permit a one-way diversion of water, said Molly Flanagan, the vice president of policy for the Chicago-based Alliance for the Great Lakes. A return-flow of an equal amount is mandated, which essentially closes the door to diversions by California, Texas, and other parched states.

Or does it? The congressionally approved Great Lakes compact could face future challenges, and even possible revisions, as issues of water quality and scarcity grow more critical, Schroeck said. What’s to stop legislation to allow water diversions to entire states, or entire regions? “With slower population growth than other parts of the country, the Great Lakes states will have less power and influence in Washington, D.C., where Congress could potentially bend to the wishes of the more populous, and water-hungry, Southern and Western states,” Schroeck said.

Added to the objections of the Waukesha deal is the underlying issue of urban sprawl. Waukesha expanded its water-service area beyond its city limits—nearly doubling the size—to include sections of four adjacent suburbs, one of them home to a private golf course. Many of these outlying areas are ripe for residential and industrial development, but water diversion is not intended for future growth under the compact. The Compact Implementation Coalition, a Wisconsin group of environmental lawyers and advocates who oppose the plan, says it is a grab for water Waukesha does not need, designed to set the table for more growth and draw businesses away from Milwaukee. “It’s urban sprawl masquerading as a drinking-water problem,” said Wisconsin State Representative Cory Mason, a Racine Democrat who chairs the Great Lakes Legislative Caucus, at a public hearing.

In late April, the caretakers of the Great Lakes Compact—designated representatives of the eight governors and two Canadian premiers—met in a public meeting in Chicago to fine-tune their response to Waukesha’s proposal. The officials parsed through the highly technical and arcane language of the compact to compile a “Declaration of Findings” to take to their respective governors for a final vote scheduled for June 13. They stripped nearly all of the adjacent suburban parcels from Waukesha’s water-service area—to Waukesha’s chagrin—deciding not to sanction the use of water diversion as a possible tool for development that could trigger sprawl. They will resume their revisions and vote on the Declaration of Findings on May 10 and 11. The panel has three options: It could declare that the proposal meets the requirements of the Great Lakes compact, does not meet the requirements of the compact, or would meet the requirements if Waukesha makes specified alterations to its plan.

Public support of the diversion plan has been lacking. During a public-comment period, 11,200 comments were sent by email and letters to the Great Lakes governors from individuals, businesses, government officials, and tribal representatives in the region: The majority opposed the diversion. Some 121 mayors with the Great Lakes and St. Lawrence Cities Initiative called for the governors to deny the application. In March, of more than 100 people attending a hearing in Duluth, Minnesota, not one spoke in favor of the diversion. Commenters cited concerns about the quality of return-flow water and the precedent the diversion would set throughout the Great Lakes region.

“What next? An application from California or the desert states?” wrote Jon MacDonald, the president of the Jackfish Metis Association. “Lake Superior only recovers some one percent [per] year from the surrounding rivers, which are predominantly Canadian, and this itself depends on rainfall, ice coverage, temperatures and weather … Although the lakes look large, they can easily be changed.”

A unanimous vote is required in June to approve the diversion. If denied, Waukesha Mayor Shawn Reilly said that his city would possibly seek legal recourse. Environmental groups, said Ezra Meyer, a water-resources specialist with Clean Wisconsin, also would consider a court challenge, depending on the outcome.

“The danger is, what happens after the decision to give or deny water to Waukesha?” said Flanagan, with the Alliance for the Great Lakes. “The way the contract deals with water, does that stand up in court? It’s impossible to tell. That part of the story will remain unwritten until long after the Waukesha diversion is decided.”