A state that's home to 10,000-plus lakes and the headwaters of the nation's marquee river is surprisingly dependent on a water supply hidden from view: groundwater.

While Minneapolis and St. Paul draw their municipal water supplies from the Mississippi River, 75 percent of Minnesotans' drinking water now comes from wells tapping the sprawling reservoirs underlying the state. That's a dramatic shift from decades gone by when surface water, such as rivers, largely slaked the state's thirst.

The vast but finite aquifers are like glasses of water with many drinking straws — perhaps too many — draining their contents. One of the most pressing challenges facing the state is ensuring that increased demand from a growing population and agricultural irrigation doesn't drain groundwater supplies too rapidly. Instead, this resource must be managed sustainably for future generations.

That's why legislation moving through the Minnesota House that would bolster and fund this important groundwater management work merits both legislative and public support. Remarkably, the Senate has ignored this critical issue in its budget proposal for the environment.

Over the past year, concerns about groundwater have escalated dramatically because of last summer's drought and because of a high-profile lawsuit alleging that White Bear Lake has shrunken due to groundwater pumping by nearby communities.

These events have made it crystal-clear that groundwater has limits and that levels below ground connect in little understood ways to the health of the state's beloved surface water. If the Minnesota Senate won't act this year, when will lawmakers take this issue seriously?

The legislation pushed in the House is not an all-encompassing solution to the state's groundwater challenges, but it would be an important first step.

The legislation would raise water appropriation permit fees by reasonable amounts on the state's big water users — such as municipalities, irrigators, industry and golf courses. The $6.1 million that would be raised annually would not go into the general fund, but would be dedicated to helping the state's Department of Natural Resources (DNR) better measure groundwater use, ensure regulatory compliance and move toward a regional management of this resource. Gov. Mark Dayton also called for improved water management and monitoring.

For far too long, the DNR has taken a permit-by-permit approach to water use rather than a cumulative view. While DNR Commissioner Tom Landwehr deserves credit for pushing to do better, updating the agency's groundwater management will require staff, better technology and more monitoring wells to manage this critical resource.

Research is also needed. As dependent as Minnesota is on groundwater, there are surprising scientific gaps in knowledge about aquifer recharge rates, impact on lakes and river levels, and other key issues.

Those who would urge the DNR to cut elsewhere before raising fees on water users haven't done their homework. The agency has already taken significant cuts for water management — a 32 percent decline in general funds over the past 12 years — just as applications for new water-use permits have jumped 67 percent. Big users of water also should be targeted to pay for better management, as opposed to a reliance on Legacy Amendment funds generated by the general public.

The fee increases are far from onerous. Big users would still pay a permit fee per gallon that is measured in the thousandths of a cent, and fees for some users would continue to have a maximum cap. Municipalities would likely pass along the increase to residents. But the DNR estimates that city water customers would see about a $1 increase annually if the legislation is passed.

The Freshwater Society estimates that "permitted and reported pumping" of groundwater rose 31 percent between 1998 and 2011. That demand curve can't continue going up indefinitely.

It may well be that some communities need to rely more heavily on surface water in the future. Some users applying for permits will need to be told no.

The proposed fee increase will ensure that these decisions, which will not be easy, will be based on solid scientific data. Lawmakers need to act this session so this important work can quickly get underway.

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An editorial of the Star Tribune (Minneapolis). Follow the editorial board: on Twitter | on Facebook | on Instagram | on Google+