A peculiar situation arising out of the increased flow through the Illinois River is the backing out of the two dams built by the State of Illinois at Henry and Copperas Creek. When first completed the lift at Henry Lock was 6 feet and that at Copperas Creek 7 feet. Under present conditions there is no appreciable fall over either dam, there being a depth of about 3 feet over each at low water. Boats drawing more than that amount of water are still required to use the locks and pay tolls, whereas if the dams were removed depths would be impaired but slightly and it would be unnecessary to use the locks. Under existing conditions these two structures are obstacles to navigation.

While the fall over the United States dams at LaGrange and Kampsville has been decreased in each case they are still of value in increasing depths in the pools above and can not be removed without considerable additional dredging being necessary to restore navigable depths.

Between 1904 and 1906 the sanitary district, under authority of the Secretary of War, lowered the crest of the United States dam at Kampsville for the express purpose of obtaining relief from flood damages due to the diversion of water from Lake Michigan. The result was a lowering of the low-water surface and a consequent reduction of depth of water which was noticeable for a distance of over 15 miles above the dam. As this lowering has proven a detriment to navigation any balancing of benefits against detriments should include the cost of restoring this dam to its original height on the debit side.

Another item on the debit side of the account would be the settling of solids from sewage in the upper Illinois River. Actual tests have shown that from 4 to 10 cubic yards of solid material are recovered from each million gallons of sewage, the exact amount depending upon the method of treatment. At the present time the sewage produced in the sanitary district is in the neighborhood of 900,000,000 gallons per day. Taking the lower rate of 4 cubic yards per million gallons the total per day becomes 3,600 cubic yards, which would cost $720 a day to remove at the cost of 20 cents per cubic yard. This amounts to about $260,000 a year. While all of this material is not deposited in the navigation channel, which is only 200 feet wide, or in places shallow enough to affect navigation depths, at least one-fifth of it is, so that the damage so far as navigation is concerned can be placed at $52,000 per year without a great amount of inaccuracy. This, of course, is cumulative and increasing. In the 23 years since the drainage canal has been opened the damage has probably amounted to over three quarters of a million dollars, so that the benefits of increased depth are partially neutralized.

Granting that conditions affecting navigation have been improved by the operations of the sanitary district, of what value is the improvement if the amount of navigation to be benefited is negligible? The following table showing the amount of commerce on the river for each year since 1917 does not indicate a widespread use of the channel afforded:

Even at present, when there are indications of a revival of waterborne commerce, the beneficiaries are extremely limited. Under present conditions a 7-foot channel is available at low stages of the river, but the average draft of loaded vessels does not exceed 41⁄2 feet. In the last analysis navigation has benefited little, if any, by the operations of the sanitary district, so that in balancing benefits against detriments this feature may be entirely eliminated from consideration as far as the Illinois River is concerned.

Future conditions may be somewhat different, however. Later on it will be shown how it is not unreasonable to expect that ultimately a 9-foot channel will be required and used in the Illinois River. Assuming that the existing 7-foot project based on a flow from Lake Michigan of 4,167 second-feet is completed, it will cost about $2,400,000 to provide a 9-foot channel between La Salle and Grafton with a flow of 5,000 cubic feet per second, or about $800,000 with a flow of 8,000 cubic feet per second. If the flow were increased to 10,000 second-feet the cost would be about $400,000.

It might be said then that a discharge of 10,000 second-feet would probably be worth $2,000,000 and one of 8,000 second-feet would probably be worth $1,600,000 as far as the future improvement of the Illinois River is concerned.

The engineers for the State of Illinois estimate that a flow of 10,000 second-feet is worth about $2,000,000 as against 5,000 second-feet in connection with the construction of the Illinois waterway, while 8,000 second-feet would be worth about $1,600,000.

For the entire stream the values become $4,000,000 and $3,200,000 for diversions of 10,000 and 8,000 cubic feet per second, respectively. This is roughly at the rate of $400 per cubic foot per second.

NAVIGATION ON THE MISSISSIPPI RIVER

The low-water widths of the Mississippi River immediately below the mouth of the Illinois are between 1,500 and 2,000 feet; at bank

full stages the widths are between 2,500 and 4,500 feet. Under present conditions the estimated extreme low-water flow is about 30,000 cubic feet per second including that diverted from Lake Michigan. (See H. Doc. No. 2, 67th Cong., 1st sess.)

The diversion of 8,000 second-feet from the lake constitutes slightly over one-fourth of the low-water flow in the Mississippi River. An inspection of the discharge curve of the river at St. Louis indicates that an increment of 8,000 cubic feet per second produces an increased. depth of 1.4 feet (Plate VIII). No other discharge curves are available for that portion of the river between Grafton and Cairo.

It would not be unwise to assume that the average raising of the water surface amounts to about 1 foot, but due to the hydraulics of the Mississippi River, where the elevation of the tops of the bars fluctuates with the height of the surface of the water, it is doubtful if the actual depths are materially increased. For this reason it is impossible to evaluate the benefit if there is any.

POLLUTION OF ILLINOIS RIVER

Reversing the flow of the Chicago River and diverting the sewage of upward of 3,000,000 people into the Illinois River has created a situation in the upper part of that stream and in the lower Des Plaines which at times is quite objectionable on account of the offensiveness of the effluent.

During the winter months and on cool spring and fall days no nuisance is perceptible except where the water is agitated. At the power house at Lockport and in the rapids of the Des Plaines River offensive odors are present at all seasons of the year, though this is not true in the open river below La Salle.

The entire stream

In warm weather conditions are much worse. from the city limits of Chicago to Peoria Lake is one large extended septic tank giving off the gases and foul odors characteristic of the septic treatment of sewage. It can not be said that this stench is noticeable any distance from the stream, in fact, the contrary is quite true. Except in extremely warm, still weather it is barely noticeable to a passenger on the upper deck of a steamboat.

On the other hand the water is not suitable for bathing, is quite disagreeable to users of small pleasure craft, and makes the water front an undesirable locality in the river towns. Operators of excursion boats have laid the falling off in their patronage to the foul conditions on the upper river. This may be partly true, but the chief reason lies in the poor accommodations afforded by packet boats which have lost their freight business.

Peoria Lake marks the end of visible contamination of the river as far as Chicago sewage is concerned. This body of water, about 15 miles long and from one-half to 2 miles in width, acts as a very effective

settling basin. Whatever contamination is apparent below Peoria is fresh enough to indicate its origin to be the latter place.

Detailed analyses and studies have been made of Illinois River conditions by the United States Public Health Service. These studies covered a period of two years of tests in the field. While the results of the tests have not been published enough has been seen of their work to substantiate the theory that by the time the sewage reaches Peoria Lake it is pretty thoroughly reduced and that conditions below Peoria are attributable to sewage from Peoria and other points farther down the river.

While conditions along the upper river are not always pleasant, they are neither so bad as to endanger the health of any community or of individuals who travel on vessels navigating the stream nor so offensive as to depreciate seriously values of adjoining property. Further contamination by increase of sewage or reduction of fresh water probably would produce the latter difficulty.

The water front from Joliet to Lake Peoria, a distance of 110 miles, is largely of agricultural or industrial occupation. The commercial and residential sections are generally so far removed from the immediate vicinity of the river as to be unaffected by its offensiveness. The actual damage to industrial and agricultural interests is practically nil; on the other hand there are undoubtedly some attractive sites suitable for residential purposes and which would command higher prices were the river less offensive. However, the valley is not thickly populated. In the entire stretch between Joliet and Lake Peoria the following are the only towns or cities of note which are located near enough to the river to be affected:

After a careful study of conditions it is not believed that there is any real damage to property values at the present time worth evaluating.

Another effect that can not be measured is the depreciation in value of the various recreational attributes of the stream. Bathing and boating are two healthful sports, while a trip on a passenger vessel under attractive surroundings is always beneficial. Bathing in the upper river is no longer safe and it long ago ceased to be a pleasure. Boating has not decreased in volume; more likely it has increased, but the local boating has given way largely to through traffic which hurries through the upper river as rapidly as possible, so that the