The most important problem, however, which the works to be undertaken—­and which must of necessity be soon commenced—­will have to solve, is not one of wharf accommodation or of increased facilities of commerce.  It is the better disposal of the sewage of the city, the system in use at present being inadequate, and growing more and more imperfect as the city and its population increase.  During the early days of Chicago, and indeed long after, the sewage question was treated with primitive simplicity, and with a complete disregard of sanitary laws.

The river and the lake in front of the city were close at hand and convenient to receive all the discharge from the drains that flowed into them.  But this condition of things had to come to an end, for the lake supplied the population with water, and it became too contaminated for use.  To obtain even this temporary relief involved much of the ground level of the city being raised to a height of 14 ft. above low water, a great undertaking carried out a number of years ago.  To obtain an adequate supply of pure water, Mr. E.S.  Chesborough, the city engineer, adopted the ingenious plan of driving a long tunnel beneath the bed of the lake, connected at the outer end to an inlet tower built in the water, and on shore to pumping engines.  This plan proved so successful that it is now being repeated on a larger scale, and with a much longer tunnel, to meet the increased demands of the large population.

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 971/4 miles, and it had a fall of 146 ft. to low water in the Illinois River (see Fig. 1).  It was