Lake Michigan is the world's fifth-largest lake. By any stretch of the imagination, communities near its shores shouldn't be grappling with water-supply issues. But Chicago and its neighbors are.

The problem stems primarily from a remarkable engineering feat in 1900, when the flow of the Chicago River was reversed. This was done to reduce upstream contaminants from reaching Lake Michigan and polluting the region's major freshwater supply source. Of course, upstream communities weren't all that happy about receiving Chicago's contaminated water, which shows the trouble created by solutions that don't take into account effects across an entire system. Jump forward a century, and a complex web of interactions and problems has evolved around management of both water supply and wastewater.

Because "used" water -- from stormwater runoff and treated sewage effluent -- is not returned to the lake, the Northern Illinois region is unique among Great Lakes communities in that the volume of water that its communities can draw from the lake is capped under a 1967 U.S. Supreme Court decree.

A Chicago-based nonprofit organization, the Metropolitan Planning Council (MPC), is part of a collaborative effort to devise and implement better systemwide solutions. MPC's water program director, Josh Ellis, explains that while the most obvious solution -- re-reversing the flow of the Chicago and Calumet rivers back to their natural direction into Lake Michigan -- is possible from an engineering perspective, that would create new problems and likely cost billions of dollars.

Chicago, for example, would have to upgrade its sewer and stormwater systems. The water level of the Illinois River, which receives water downstream from the Chicago River, would drop, a possibility that concerns communities along the Illinois River's shores. Among a host of other factors, there's also the potential for invasive species to enter the Great Lakes from the Mississippi, causing both ecosystem and economic upheavals.

Ellis acknowledges that some might prefer not to have a cap on the region's water supply, but he says limiting the water supply has its upside: "opportunities to wring inefficiencies out of the water system."

There's plenty of inefficiency to go after. "The best available data suggest there are 70 million gallons of water lost through leaking pipes from the Lake Michigan distribution system every day," Ellis says. "That water was pumped, treated and pumped again, but never arrived at the tap or showed up on a bill."

That 70 million gallons amounts to about 8 percent of the water that flows into the system. And as significant as the water losses are, they don't take into account the wasted energy and dollars involved in pumping treated water that never gets purchased. In short, there are strong arguments for extending the water supply through better efficiency rather than by simply removing the cap.

Under a series of rule changes proposed by the Illinois Department of Natural Resources, communities drawing water from the lake would be required to provide better assessments of how much water they're losing in their systems. They also would need to strengthen their policies related to usage factors such as plumbing codes and watering of gardens and lawns.

The resulting system, Ellis says, "would look more like a western state than an eastern one, with robust permitting programs, conditions-of-use requirements and loss-monitoring analytics." Those analytics also could help prioritize where federal, state and local investments should be made to improve infrastructure and services in coming years.

MPC planners would like to see these kinds of smart water-management practices spread across the Great Lakes region to save money and extend the water supply. With water levels at historic lows, this makes a great deal of sense.

Although the engineers of 1900 likely never envisioned the problems their handiwork would create, it's a great sign that today's regional leaders are making use of lessons learned to eliminate waste, save money and demonstrate how regional collaboration can produce strong positive outcomes.

This column has been updated to eliminate an incorrect reference to the amount of water lost through the Lake Michigan distribution system.