But to improve the sanitary condition of the city has been a much more difficult undertaking, as may be gathered from the following extract from an official report: "The present sanitary condition calls loudly for relief. The pollution of the Desplaines and the Illinois Rivers extends 81 miles, as far as the mouth of the Fox (see plan, Fig. 1) in summer low water, and occasionally to Peoria (158 miles) in winter. Outside of the direct circulation the river harbor is indescribable. The spewing of the harbor contents into the lake, the sewers constantly discharging therein, clouds the source of water supply (the lake) with contamination. Relief to Chicago and equity to her neighbors is a necessity of the early future." To make this quotation clear it is necessary to explain the actual condition of the Chicago sewage question.
Long before the present metropolis had arrived at the title and dignity of a city, the advantage to be derived from a waterway between Lake Michigan and the Illinois River, and thence to the Mississippi, was well understood. The scheme was, in fact, considered of sufficient importance to call for legislation as early as 1822, in which year an act was passed authorizing the construction of a canal having this object. It was not commenced, however, till 1836, and was opened to navigation in the spring of 1848. This canal extended from Chicago to La Salle, a distance of 97¼ miles, and it had a fall of 146 ft. to low water in the Illinois River (see Fig. 1). It was only a small affair, 6 ft. deep, and 60 ft. wide on the surface; the locks were 110 ft. long and 18 ft. wide. The summit level, which was only 8 ft. above the lake, was 21 miles in length. This limited waterway remained in use for a number of years, until, in fact, the growth of Chicago rendered it impossible to allow the sewage to flow any longer into the lake. In 1865 the State of Illinois sanctioned widening and lowering the canal so that it should flow by gravity from Lake Michigan. The enlargement was completed in 1871, by the city of Chicago, and the sewage was then discharged toward the Illinois River. But the flow was insufficient, and in 1881 the State called on the city to supplement the flow by pumping water into the canal.
The physical nature of the country is well suited for carrying out such a project on a scale far larger than that required for sewage purposes, and works thus carried out would, to a small extent, restore the old water regime in this part of the continent. Before the vast surface changes produced during the last glacial period, three of the great lakes—Michigan, Huron and Superior—discharged their waters southward into the Gulf of Mexico by a broad river. The accumulation of glacial debris changed all this; the southern outlet was cut off, and a new one to the north was opened near where Detroit stands, making a channel to Lake Erie, which then became the outlet for the whole chain by way of Niagara. A very slight change in levels would serve to restore the present regime. Around Lake Michigan the land has been slightly raised, the summit above mean water level being only about 8 ft. Thirty miles from the south shore the lake level is again reached at a point near Lockport (see Fig. 2); the fall then becomes more marked. At Lake Joliet, 10 miles further, the fall is 77 ft.; and at La Salle, 100 miles from Chicago, the total fall reaches 146 feet. At La Salle the Illinois River is met, and this stream, after a course of 225 miles, enters the Missouri. In the whole distance the Illinois River has a fall of 29 ft. "It has a sluggish current; an oozy bed and bars, formed chiefly by tributaries, with natural depths of 2 ft. to 4 ft.; banks half way to high waters, and low bottoms, one to six miles wide, bounded by terraces, overflowed during high water from 4 ft. to 12 ft. deep, and intersected in dry seasons by lake, bayou, lagoon, and marsh, the wreck of a mighty past."
The rectification of the Illinois and the construction of a large canal from La Salle to Lake Michigan are, therefore, all that is necessary to open a waterway to the Gulf of Mexico, and to make Chicago doubly a port; on the one hand, for the enormous lake traffic now existing; on the other, for the trade that would be created in both directions, northward to Lake Michigan, and southward to the Gulf.
As a matter of fact this great scheme has long occupied the attention of the United States government. A bill in 1882 authorized surveys for "a canal from a point on the Illinois River, at or near the town of Hennepin, by the most practical route to the Mississippi River ... and a survey of the Illinois and Michigan Canal connecting the Illinois River with Chicago, and estimates from its enlargements." This scheme only contemplated navigation for boats up to 600 tons. In 1885 the Citizens' Association, of Chicago caused a report to be made for an extended plan. The name of Mr. L.E. Cooly, at that time municipal sanitary engineer, was closely associated with this report, as it is at the present time for the agitation for carrying out the works. This report recommended that "an ample channel be created from Chicago to the Illinois River, sufficient to carry away in a diluted state the sewage of a large population. That this channel may be enlarged by the State or national government to any requirement of navigation or water supply for the whole river, creating incidentally a great water power in the Desplaines valley." Following this report and that of a Drainage and Water Supply Commission, a bill was introduced into Congress supporting the recommendations that had been made, and providing the financial machinery for carrying it into execution. Since that date much discussion has taken place, and some little action; meanwhile the sanitary requirements of the city are growing more urgent, and the pressure created from this cause will enforce some decision before long. Whether the new waterway is to be practically an open sewer or a ship canal remains yet to be seen, but it is tolerably certain that its dimensions and volume of water must approximate to the latter, if the large populations of other towns are to be satisfied. In fact the actual necessities are so great as regards sectional area of canal and flow of water—at least 600,000 ft. a minute—that comparatively small extra outlay would be needed to complete the ship canal.
As will be seen, the canal commencing near the mouth of the Chicago River passes through a cut in the low ridge forming the summit level; then it runs to Lake Joliet, and through the valleys of the Desplaines and Illinois Rivers, to the Mississippi at Grafton, a distance of 325 miles. The elevations and distances of the principal points are as follows:
| Miles from Lake Michigan. | Low Water Level below Chicago Datum. | High Water above Low Water. | ||
| ft. | ft. | |||
| Lake Michigan | 4.7 | |||
| Lake Joliet | 40 | 77 | 5 to 6 | |
| Kankakee River | 51.30 | 93.70 | 18 to 20 | |
| Morris | 61 | 100.3 | 21 | |
| Marseilles | 77 | 102.8 | 4 to 5 | |
| Ottawa | 84.5 | 132.1 | 26 | |
| La Salle | 100.3 | 146.6 | 28 | |
| Hennepin | 115.8 | 148.7 | 25 | |
| Peoria | 161.4 | 151.3 | 21 | |
| Mouth of the Illinois | 325 | 172.4 | 20 |
The project in contemplation provides that the depth of the canal as far as Lake Joliet (which is about six miles long) shall be not less than 22 ft., and on to La Salle not less than 14 ft. at first, with facilities to increase it to 22 ft. Beyond La Salle to the mouth of the Illinois, dredging and flushing by the large volume of water pouring in from Lake Michigan would make and maintain ultimately a similar depth.