Lake Levels

Of recent years, the layman has heard much of suits brought against the city of Chicago for reducing the level of Lake Michigan, and thus of the other Great Lakes, with her drainage canal emptying into the Mississippi basin. Only last fortnight the Supreme Court granted extension of the scope of these suits (TIME, March 15). The picture commonly conjured by such news shows Great Lakes cities other than Chicago left high and dry on their banks, steamers stranded on widening beaches, steamers loitering off-shore unable to unload rich cargoes--all on account of a great outpouring of water from the foot of Lake Michigan.

An article in the current Scientific Monthly by a resident of one of the suing states, Professor Herman L. Fairchild of the University of Rochester (N. Y.), corrected this picture with the following facts, now well known to engineers that have surveyed the Lakes-level problem for some years:

The Chicago canal opened in 1900, was designed to effect a flow of 10,000 cubic feet a second. In 1923 the War Department obtained an injunction to have this limited to 4,167 c.f.s and has allowed Chicago time to adjust matters.

In 25 years the 10,000 c.f.s. flow has lowered Lakes Michigan and Huron a total of 5 inches, reducing the flow of Niagara by 5%. Lake Erie's diminution corresponds; Lake Superior has been virtually unaffected owing to partial control of its outlet by dams.

But in the past six years there has been a steady drop in the levels of all the Great Lakes, even including Superior, of over two feet on the average. Much of this fall has been laid at Chicago's door, whereas in actuality it was owing to meteorologic causes--"some slight and indeterminate shifting of the great atmospheric currents which flow eastward, at high altitudes," across this latitude. Five inches in 25 years is not much of a patch on two feet in six years, and an engineering board of review has recommended that the Chicago drainage canal be permitted to continue for three reasons: otherwise flooded streams and storm water would, owing to Chicago's topography, flow into Lake Michigan making it even more foul than it now is near the city; the "Gulf to Lakes" commerce route is of great value and needs the full flow; the other Lakes can easily overcome the slight effect of the canal by constructing dams at their outlets as Superior has done.*

Striking figures were presented on the 31-inch lowering of the Michigan-Huron water-level in the last six years:

Unusual evaporation and scanty rains in six years of weather warmer than average.......13 in.

Increased outlet by widening the St. Clair River..................... 8 in.

Diversion at Chicago..................................................5 in.

Storage and retention in Superior.....................................3 in.

Diversion from Erie (Welland Canal, Black Rock canal, N. Y. State Barge Canal)................................................................. .......2 in.

*In glacial times, when the ice sheet still blocked the Mohawk and St. Lawrence valleys, there were two southerly outlets to the Great Lakes system, the present Wabash and Desplaines-Illinois valleys, both leading to the Mississippi. The latter ultimately robbed the former and a vast river, called Warren River after the engineer who traced its old scourway, carried the entire system's outlet. The Chicago canal follows that scourway, deepened but a few feet. There was, in the Warren River's day, a "Lake Chicago" spreading out over the present state of Michigan ; Huron, Erie and Ontario were a "Lake Warren" with an outlet across Michigan into "Lake Chicago."