produced daily becomes 1,329,400,000 gallons which is equal to a rate of 2,051 cubic feet per second. Using round numbers and deducting this from the actual total flow of 8,000 cubic feet per second the amount of fresh water supplied becomes 6,000 cubic feet per second. In other words, under present conditions about 30 parts of oxygen per million of sewage are supplied by the dilution water where 121 are necessary, leaving a deficiency of 91.

Moving water, and even stagnant water, will absorb a certain amount of oxygen from the air, the amount absorbed depending upon the temperature, the velocity of flow, and the depth of the body of water or channel. The average rate of flow in the drainage canal is about 2 miles per hour. The distance from Lake Michigan to the power house at Lockport is a little over 36 miles, making the time of flow from the lake to the Des Plaines River about 18 hours. The rate of reaeration of water varies from one hour for a rapidly moving shallow stream to 20 hours for a sluggish deep channel. As conditions in the drainage canal more nearly approximate the latter a rate of reoxidation of 18 hours will be assumed. The 30 parts of oxygen per million of sewage will be increased, therefore, to 60 parts by the time the mixture has reached the Lockport power house.

When the effluent leaves the treatment works of the sanitary district, namely, the main drainage canal, and is discharged into the valley of the Des Plaines and Illinois Rivers, not enough oxygen is present or has been added to the mixture to completely oxidize the organic constituents. Inspection of data obtained by the United States Public Health Service, and making allowance for the contamination added at La Salle and Peru, indicates that the oxygen demand, so far as Chicago sewage is concerned, does not reach a minimum until some distance below Peru is reached.

But no system of sewage treatment is devoid of stench at all times. One community or another is likely to be affected. In this case it is not the community which produces the nuisance, hence the just cause for complaint if it becomes too offensive. However, it is not believed that the Government should be called upon to contribute to abating a nuisance for which it is not responsible, particularly when no real damage is apparent. Maintenance of status quo, so far as condition in the Des Plaines or Illinois Rivers are concerned, will not involve the United States Government legally or morally in loss of life, improvement of health, or serious depreciation of property values.

NAVIGATION

As far as the navigation of the Chicago River and the drainage canal is concerned, if the flow at Lockport were entirely throttled 98203-241- -5

and the power-house gates closed so as to permit no diversion from Lake Michigan, conditions would be decidedly improved. The current which now averages 11⁄2 miles per hour and in some bridge draws is as high as 4, would be practically eliminated, making nagivation considerably simpler, especially for the larger vessels whose passage through a narrow bridge draw is apt to increase the current materially.

The Illinois waterway is only about 15 per cent completed and at the present rate of progress will not be ready for use for some time to come. The question of flow is entirely unaffected by any immediate needs of this waterway. The amount of flow to be expected when the enterprise is finished has a definite bearing upon the plans of the structure. But as Part IV deals with immediate needs, a study of the amount of water necessary for the operation of the waterway some 10 years from now will be left for later consideration.

On the improved portions of the Illinois River depths have been materially benefited by the introduction of Lake Michigan water. The present project contemplates the completion of a 200-foot channel 7 feet deep based on a diversion of 4,167 cubic feet per second. If the project were completed the flow could be reduced to 4,167 cubic feet per second and cause no injury to navigation. It is estimated that about 1,700,000 cubic yards of material would have to be dredged to complete the project. This would require from three to four years' time with a 15-inch suction dredge such as is contemplated for the river. With the expenditure of about $973,000, inclusive of funds available, the project will be completed by 1928. A reduction in diversion to 4,167 cubic feet per second could not be made without detriment to navigation before that time.

If the flow were reduced to 5,000 cubic feet per second an expenditure of about $800,000, exclusive of available funds, would provide ample depths for navigation by 1927. A reduction to 6,000 cubic feet per second could be made at the present time without material injury.

RECOMMENDATION OF ALLOWANCE TO CARE FOR PRESENT NEEDS

Reviewing what goes before it will be seen that the present average diversion of about 8,000 cubic feet per second is more than ample1. To protect Chicago's water supply. 2. To sufficiently dilute the sewage.

3. To care for the needs of navigation.

No consideration should be given to the needs for water power, as an ample supply of steam power at a reasonable rate exists in the locality to replace the relatively small amount produced by the sanitary district. As far as the protection of the investment of the

sanitary district is concerned, it may be said that while the works may have been designed for a flow of 10,000 cubic feet per second, a fair return has already been earned and a diversion of 8,000 cubic feet per second permits the continued use of all the completed structure. The power available in the additional 2,000 cubic feet per second may be of some importance to the sanitary district and other corporations producing hydroelectric energy along the river, but in view of the fact that the net economic loss to the United States as a whole would amount to $540,000 per year or a capital loss of $10,800,000, the desires of the sanitary district authorities in this regard should not be permitted to prevail.

PART V

STEPS TO BE TAKEN TO REDUCE AND COMPENSATE FOR THE DIVERSION

SEWAGE DISPOSAL BY OTHER METHODS THAN DILUTION

Assuming that the Sanitary District of Chicago needs 8,000 cubic feet per second at the present time and is allowed that much, what of the future? The population of the district is increasing at the rate of 70,000 per year and this rate is increasing. Every year the sewage of 70,000 people is added, besides the pollution from industrial wastes, estimated to be equivalent to the pollution from 30,000 people. This equivalent increment of 100,000 persons per year adds 28,900,000 gallons per day of sewage which with its dilution water amounts to approximately 200 cubic feet per second. By 1950 the total amount diverted from Lake Michigan would be about 13,000 cubic feet per second, by 1975 it would be over 18,000. Having provided for present sanitation needs by diverting 8,000 cubic feet per second, the next step, and perhaps the most important one, is to provide for the disposal of any increase in the amount of sewage produced by methods other than dilution.

Sewage-treatment processes are no new discovery. They have been in existence for a great many years, and while changes occur in methods and old plants become obsolete and require rebuilding or replacing the same condition obtains with respect to any other industry. The only difference between the problem confronting the Sanitary District of Chicago and any other community facing the necessity of treating its sewage is the magnitude of the problem. The local officials assume an attitude of being overawed every time the subject is mentioned. At no time have they taken the position of being in control of the situation or of meeting it squarely. Such a state of affairs requires temerity of the kind exercised by their predecessors in office, who despite the opposition from within and without, carried out the remarkable construction program which produced the main drainage canal.

There can be no question as to the efficacy of sewage-treatment processes. Between 1905 and 1915 the population in the United States connected to systems whose sewage is treated in some way increased from 1,100,000 to 6,900,000, over 600 per cent, while the total population connected to sewer systems of all kinds increased from 28,000,000 to 41,800,000. Treatment of sewage in large cities is rapidly becoming the rule, rather than the exception.

The officials of the sanitary district have no grounds for delay on account of lack of complete information as to the processes best suited to the different kinds of sewage produced. For over 10 years their testing laboratories have carefully investigated every kind of sewage, have tabulated characteristics, and determined behavior under every kind of treatment. There is no question but what their engineers have been ready to go ahead with the work for some years, but without the stimulus now produced by a prospective Federal injunction inaction seems to have been the slogan of the trustees, and the valuable investigations of their engineering department have been pigeonholed.

However, it must be said to their credit that a program has been prepared under their direction which if actually adopted and adhered to will accomplish the results desired, that is, preclude the necessity of increasing the amount of water diverted from Lake Michigan without endangering the health of the community. This program is supposedly in compliance with a law passed by the legislature of the State of Illinois in 1921, a copy of which will be found in Appendix 16.

The first seven columns of the following table (Table 7) have been prepared by the assistant chief engineer of the sanitary district. These are all agreed to except the last which indicates the amount of diversion necessary in order to comply with the State law. The State law requires a diversion of 3 cubic feet per second per 1,000 people but makes no reference to equivalent population of industries. Column 8 has been added showing the actual human population whose sewage is not treated, and column 9 indicates diversion actually required by the State law properly interpreted.

But how can a law drafted nearly 35 years ago apply to conditions now existing? The ratio adopted and written into the law was the result of a careful study of conditions as they existed at that time. The construction of the drainage canal had not been begun and consequently its characteristics were unknown. Little or nothing was known about the oxygen demand of the sewage, and had it been determined, it would hardly be safe to say that it would remain unchanged throughout a period of 35 years. A better criterion of present and future needs will be found in conditions as they actually exist to-day, not as they were expected to exist to-day.

In Part IV it was stated that with an industrial and human pollution equivalent to that produced by 4,600,000 people a diversion of 8,000 cubic feet per second was being used to provide an initial supply of oxygen for the purpose of oxidizing the organic constituents. This diversion is at the rate of 1.74 cubic feet of water per second per each 1,000 of equivalent population. Using this factor instead of 33, and taking the population equivalents in column 6, the amounts shown in column 10 result.