The Illinois Department of Natural Resources has proposed an update to the rules for diverting water from Lake Michigan. Northeast Illinois takes hundreds of millions of gallons of water out of the lake daily for municipal use and for diversion into the Chicago area waterway system, but a great deal of the diverted water actually escapes through leaky pipes.

“We waste a lot of money pumping, treating, distributing water that never gets sold,” said Josh Ellis of the non-profit Metropolitan Planning Council.

Ellis estimates that as much as 70 million gallons a day are lost to leaks in aging infrastructure across the region. That’s the equivalent of a Willis Tower full of water every few days, a loss that may not be sustainable as the regional population grows or new municipalities in northeast Illinois move to using Lake Michigan water.

“The time to start thinking and figuring out what needs to be done is now,” said Daniel Injerd, the chief of Lake Michigan management for IDNR. “We need, as an agency, to try to send a stronger message to communities to say it’s really time to start looking at water loss.”

IDNR is in charge of the permits for all Illinois entities who get water out of Lake Michigan, including the U.S. Army Corps of Engineers and the Metropolitan Water Reclamation District, and for the first time since 1980, the agency is proposing a significant change to the permitting policy. Rather than allowing a certain amount of leakage based on the age of the pipes in a village, town, or city, the new permitting process would require municipalities to account for all their water — or submit a detailed plan for how to update aging infrastructure. Injerd says more than half of the 215 agencies that now have water allocation permits would be in violation of the leakage limits under the new rule.

The revised water diversion rule also includes more strict limitations on sprinkler use and requirements for water-efficient plumbing in new construction. Finally, the proposed documents suggests, but does not require, that municipalities adjust the price of water to reflect the real cost of moving and treating water and of upgrading water infrastructure.

Ellis thinks the proposed changes should go even further.

“Right now most water rate systems don’t generate enough revenue to cover the full costs of providing water services,” said Ellis. “We’re paying for the pipes, the pumps, the chemicals, the electricity…we feel that IDNR, through its permit conditions can prompt more municipalities to develop rate systems that generate enough revenue to pay for these things.”

Short of raising prices or pulling from other revenue sources, right now municipalities have to seek out state loans to support infrastructure upgrades.

But Injerd says IDNR is not planning to impose requirements on water pricing.

“Probably most of our permittees think that’s not an area we need to delve into,” said Injerd. “It’s really not our role as a state agency to set water rates. But I have no problem recommending that communities develop a water rate that represents the true cost of providing a water supply.”

A 1967 Supreme Court decision limited Illinois’ water diversion from the lake, and it’s the role of the DNR to see that what the state pulls out doesn’t exceed that limit. A full quarter of the water diverted by Illinois is stormwater runoff that would have been returned to Lake Michigan via the waterways before the Chicago River was engineered to flow out of the lake in 1900.

Public comment on the proposed water allocation rule change is open through the end of May, and the Metropolitan Planning Council will be holding an event Tuesday May 8 to discuss Lake Michigan water loss.

Lewis Wallace is a Pritzker Journalism Fellow at WBEZ. Follow him @lewispants.