Court’s initial ruling in 1930. First, the Court sided with Chicago

by boosting the total amount of the diversion from 1,500 cfs to

3,200 cfs. That meant that the diversion could total 2.1 billion gal-

lons of water per day. But while the Court upped the amount of the

diversion, it also tipped its hat toward Wisconsin by forcing Illinois

to count water that it had never been required to keep track of be-

fore. For the first time Chicago drinking water and other “domestic

pumpage” (which had been virtually ignored) had to be included in

the 3,200 cfs number.

Interestingly, the decree also required Illinois to undertake a

seemingly impossible task: calculate the annual amount of rainfall

that fell in the 673-square-mile Chicago River watershed. This rain

used to end up in Lake Michigan after running off into the once-

natural flowing Chicago River. But with the diversion that rain

ended up trickling into a backward-flowing Chicago River and was

therefore a hydrologic loss to the Lake Michigan system. The Court

(again nodding to Wisconsin) wanted Illinois to include that rain-

fall amount as part of the new 3,200 cfs number.

But the most important part of the Court’s decision was a re-

sounding victory for Illinois. In a key move, that had enormous im-

plications for future growth in the greater Chicago area, the Court

permitted Chicago’s suburbs to tap into the city’s Lake Michigan

drinking-water system—even if the suburbs were far beyond the

Great Lakes Basin boundary. In addition, the Court gave Illinois

full authority to decide which communities could be added to the

Lake Michigan drinking-water system—again, as long as the state

stayed below the 3,200 cfs limit. The Chicago suburbs that were ex-

periencing groundwater problems had suddenly found a new water

source that would allow the metropolitan area to expand unhin-

dered for the foreseeable future.

That some of Chicago’s western suburbs—located far beyond

the Great Lakes Basin line—are drinking Lake Michigan water

seems patently unfair to contemporary opponents of Great Lakes

diversions. And there are a number of water-troubled communities

in other Great Lakes states that would love to access Great Lakes

water, but because these areas lie outside the Basin line their water

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