Nearly a decade ago, eight governors shook hands on an extraordinary agreement to erect a legal wall around the largest source of fresh water on earth — the Great Lakes.

The unusual bipartisan compact, signed by the heads of the states that border the massive basin, aimed to keep the increasingly valuable water right where it is for the 40 million people who rely on it for their jobs, their homes and their vacations.

Now they face the first test.

Waukesha, Wis., a suburb of Milwaukee, has asked for the right to pull drinking water from Lake Michigan. In coming weeks or months the current eight governors, including Gov. Mark Dayton, will have to make a critical decision on how to share — or not — one fifth of the world’s fresh water. The question arises against a backdrop of increasing national conflicts over water and growing concerns about the way pollution and climate change are threatening the world’s water supply.

Yet the eight governors, none of whom were in office when the compact was signed, will also have to live with the precedent they establish. Some of their own communities may someday face the same water problems that Waukesha has now — declining and increasingly contaminated supplies. Minnesota, for one, has a dozen communities with water problems that are close enough to Lake Superior to ask for an exemption under the compact.

“The real reason many of us care is not because of that one straw into the Great Lakes,” said Molly Flanagan, vice president of policy for the Great Lakes Alliance, a nonprofit that’s advocated for the compact since its inception. “If we don’t set a strong precedent, it could be too easy for other cities to stick a straw into the Great Lakes.”

The first critical meeting is April 22 in Chicago, home of the Conference of Great Lakes Governors, with representatives from each state.

Dayton’s representative, Julie Ekman, declined to say which way Minnesota is leaning. “We will be discussing what each party feels about the proposal,” said Ekman, a manager with the Minnesota Department of Natural Resources. “Can it be approved, can conditions be added or is it a nonstarter?”

The final vote is expected May 23. And it has to be unanimous — a single no vote will torpedo Waukesha’s request.

Regional competitiveness

The compact is a historic, and rare, regulatory framework. Unlike the divisive water-sharing laws for the Colorado River and others in the west, the Great Lakes compact includes language that emphasizes sustainability, transparency, conservation and efficiency.

“The compact is more about governing the resource collectively as a common pool for the public domain,” said Jenny Kehl, a professor at the University of Wisconsin, Milwaukee, who studies water resource issues.

But its most important provision, and a key reason why eight governors, eight legislatures, Congress and the president of the United States approved it, is a ban on siphoning water outside the basin.

In short, there can be no Keystone Pipeline for water to the parched agricultural lands of California.

“A big part of our competitive advantage is that we have all this water,” said Flanagan. “Exporting it would be exporting the jobs and economic benefits of having that great resource in our region”

For now, the only communities allowed to use the water are those inside the Great Lakes Basin watershed itself — Chicago, Duluth, Milwaukee are some of the big ones. And the water they use must be cleaned up and returned to the watershed.

The compact, however, gives the governors the power to make some limited exceptions for cities and counties that are part inside and part outside the watershed — so called “straddling” communities. In the wide suburban rings that surround big Midwestern cities such as Milwaukee, there are many. Even in Minnesota, where the Lake Superior watershed extends a short way inland from North Shore and up to the Iron Range, 76 towns fit the definition — 11 of them with water supplies that are even now vulnerable to contamination.

The bar they would have to meet is extremely high: Communities must show an urgent need and no other reasonable alternative.

Growth grab?

Waukesha, a well-to-do suburb west of Milwaukee, is the first that sits entirely outside the Great Lakes watershed to ask.

The city’s drinking water is contaminated with radium, a naturally occurring pollutant that can cause cancer. In addition, its water comes from deep aquifers that are running dry, and the city is under court order to find another source.

After more than a decade of analysis and reviewing many alternatives, both the city and the state concluded that Lake Michigan is the town’s only reasonable option, and that it fits the requirements of the compact.

The chorus of outraged disagreement, however, has been deafening.

“Waukesha simply assumes that its proposal to seize water from Lake Michigan will solve problems it could have more inexpensively and simply solved without drastic resort to the use of Lake Michigan water,” wrote 100 members of the Great Lakes Legislative Caucus, including many legislators from Minnesota.

The city of Milwaukee had offered to sell its neighbor the water it needed, until Wisconsin state officials required Waukesha to expand its water supply service territory to match its sanitary sewer system — part of the state’s long-range water planning. As a result, the city upped its potential water use from 6 million to 10 million gallons per day.

“We are concerned that Waukesha grossly overestimates its future water needs by expanding its service area to include communities that have neither requested nor need water service,” said members of the Milwaukee City Council.

Many critics say the water is nothing more than fuel for the city’s ambitious economic growth plans.

“These people are developers,” said Sandy Hamm, a lifelong resident of the area and an outspoken critic of the diversion plan. “There’s no other reason to want that much water.”

Dan Duchniak, Waukesha’s city water utility manager, said the increase in supply and service areas is required to comply with state law, and the potential for industrial expansion is just 15 percent. But that’s been a hard case to make, he said.

“Our opponents’ message is easy — ‘Save the Great Lakes,’ ” he said. Our message is ‘Give Waukesha Water.’ It doesn’t go down real well.”

Besides, he warned, Waukesha’s Plan B would mean drawing down other local aquifers that will have a major impact on wetlands. “And we will be back at this table 20 years down the road and we will be requesting Great Lakes water again,” he said.

Proving the compact?

Duchniak argues that granting the city’s request will actually prove that the compact works, and could avert court challenges in the future. Even if other cities do follow Waukesha’s lead, at most it means the wall around the Great Lakes Basin would extend to the outer edge of the counties that surround it.

“The water will not go beyond that,” he said.

Flanagan, from the Great Lakes Alliance, sees it differently.

“You cannot draw an arbitrary line around the counties” and expect it will stand up to court challenges, she said. The high bar outlined in the compact is there for a reason, she said: To create a legally defensible standard rooted in preserving the lakes.

Otherwise, she said, “How do you close the door?”