Wisconsin v. Illinois
The Supreme Court set a firm, phased schedule forcing Illinois and the Sanitary District of Chicago to sharply cut the amount of Lake Michigan water they divert to carry away Chicago's sewage, rejecting the state's request for more time based on a recent rise in the lake's level.
The Court entered a formal decree with specific diversion caps and deadlines running through 1938, ordered Chicago to keep filing progress reports with the Court, and made clear the state must find a way to comply even if it has to amend its own constitution to do so.
“They must find out a way at their peril.”
The Court's blunt statement that Illinois had to solve the sewage problem without further excuses.
How it got here: After the Court's earlier ruling (278 U.S. 367) found the diversion illegal, it sent the case back to a master to recommend a compliance schedule; both sides then filed exceptions to the master's report.
The Case in Depth
What happened
Illinois and the Sanitary District of Chicago had reversed the Chicago River and dug a drainage canal to carry the city's sewage away by diluting it with huge amounts of water pulled from Lake Michigan. Other Great Lakes states sued, arguing this diversion was lowering the lake's level and harming their interests. The Supreme Court had already ruled the practice illegal but allowed a gradual, rather than immediate, fix.
The question before the Court
How quickly did Illinois and Chicago have to cut back the huge amount of Lake Michigan water they were diverting to flush away the city's sewage?
Why it matters
Neighboring Great Lakes states and Canada benefited because less water would be siphoned out of the lake system, helping stabilize lake levels that affect shipping, shoreline property, and water supplies. Chicago and Illinois had to build costly sewage treatment infrastructure on a fixed timetable instead of continuing to rely on lake water to dilute untreated waste.
What changes now
The Court entered a decree capping diversion at 6,500 cubic feet per second starting July 1930, dropping to 5,000 by the end of 1935, and to 1,500 by the end of 1938, all beyond ordinary domestic water use. Chicago's Sanitary District must file semiannual progress reports, and any party can return to the Court to seek adjustments as construction proceeds or circumstances change. The Court also left open the possibility that Congress could later step in to set different terms.
What this does not decide
The Court did not decide whether Congress could later set different diversion limits under its own constitutional authority, nor did it resolve whether domestic water use should cover large industrial plants within the Sanitary District — both were left for possible future consideration.
Concurrences and dissents
How the Justices voted
Majority (1). Justice Holmes (author).
How the Court got there
The legal reasoning, step by step
- The Court began from its prior ruling that Illinois and the Sanitary District were wronging the complaining states by diverting Lake Michigan water and that they had to stop; the only remaining question was how much time and what reductions were fair.
- The Court held that Illinois could not use its own constitutional or administrative difficulties as an excuse, reasoning that a state cannot rely on problems of its own making and must yield to federal authority if its own law gets in the way.
- The Court refused to let a recent, possibly temporary rise in the lake's level delay the reductions, reasoning that the complaining states' right to relief was a present constitutional entitlement not to be discounted by speculation about future conditions.
- Applying the proportionality approach from an earlier interstate water dispute (a case holding that relief must weigh relative harm and delay by the parties, not just push a legal claim to its logical extreme), the Court declined the complainants' request to close the canal entirely and return purified water to the lake, since the withdrawal for ordinary domestic use had never been challenged.
- The Court adopted the master's specific declining diversion caps and deadlines, choosing ongoing reporting to the Court over appointing a supervisory commission, while keeping the case open for future modification.
Doctrinal impact
Cases affected by this decision
Reaffirms Missouri v. Illinois (200 U.S. 496)
Relied on for weighing relative harm and delay before granting the full relief demanded by the complaining states.
Reaffirms North Dakota v. Minnesota (263 U.S. 583)
Cited as authority for making the defendants pay the costs of the suit.