places along the stream no longer benefit by its proximity in that respect.

There never has been much passenger traffic on the upper river. One packet line-the Swain Line-operated a daily service between La Salle and Peoria for a great many years. This service was discontinued this last year, due largely to the fact that the freight business was all gone. At the present time, therefore, there is no loss to the passenger business as a result of pollution of the river.

FISHING ON THE ILLINOIS RIVER

Until recent years the fishery of the Illinois River was with but one exception the most important river fishery of the country. In 1908 the fish taken for commercial disposal from the Illinois River approximated 24,000,000 pounds, having increased to that amount from 6,000,000 pounds taken in 1894. This remarkable growth was due to several causes, notably the introduction of the German carp, the increase in extent of breeding places brought about by the Chicago drainage canal, and the food value of the products of the accompanying sewage.

Since 1908 there has been a marked falling off in the amount of catch so that at the present time it is about one-third of the size it attained in 1908. Many have attributed this falling off in the fish. catch to the increasing contamination of the water of the Illinois by Chicago sewage. This, probably, is true for the upper reaches of the river, for the consumption of oxygen by the sewage in the process of being reduced leaves nothing to support fish life. But in the earlier days of the fishing industry most of the catch was in the lower reaches where the contamination of the sewage does not extend. Furthermore, the plant organisms resulting from the organic food supplied by the sewage increased the supply of fish food on the lower river so that fish life was really a beneficiary of the introduction of sewage in large quantities from Chicago.

With reference to this, Dr. Stephen A. Forbes in his volume "The Fishes of Illinois," as published by the Natural History Survey of Illinois, says:

The Chicago sewage comes into the river at its upper end in a raw state-not available; that is, as a food for fishes. It is rapidly decomposed in the upper part of the stream in midsummer and in its decomposition it takes the oxygen out of the water, but becomes itself converted into what we call nitrites and then into nitrates, in which latter stage it becomes available food for plants and indirectly food for animals, and these in turn are food for our river fishes. This process of conversion of raw sewage into available food is a gradual one, progressing downstream at various rates according to the stage of water and the temperature at the time; but I have a good deal of reason to suppose that by the time the water has reached the central section this conversion process is practically complete and that here, consequently, this added food becomes generally available for the sustenance of fishes.

One important cause for falling off in the fish yield in the lower river has been the decrease in size of breeding and feeding grounds brought about through the reclamation of the lakes and swamps and the decrease in size of fishing grounds from the same cause. Between the years 1904 and 1914 over 18,000 acres of lakes bordering the Illinois River and used as breeding and feeding grounds had been leveed and drained; this out of a total of 49,000 acres. The amount has since been increased so that now over one-half of the old breeding grounds are gone. In view of the fact that the fishes breed, to a large extent feed, and are taken by the fisherman mainly in the lakes or overflowed marshes, it requires no lengthy argument to prove that levee construction and not sewage contamination has been the chief contributing factor in the decline of the fishing industry in the Illinois River.

The effect on fish life has been beneficial, if anything, for the bulk of the fishing industry has always been located below Peoria and what little loss has been occasioned by the partial destruction of fish life in the upper river has been more than compensated for by the benefits resulting from the increase in food supply below. As this benefit is not capable of being measured no valuation will be placed on the effect in the fishing industry.

FLOOD DAMAGES ON THE ILLINOIS RIVER

Damages due to flooding out property of riparian owners at low stages of the river have been stated elsewhere as amounting to $4,500,000. At 5 per cent this represents an annual loss of $225,000. More water would mean more flooding. At the present time there are about 170,000 acres of land along the Illinois River subject to overflow in time of floods and not under levee. Of this area 100,000 acres probably will be leveed in the not distant future. Most of the remaining 70,000 acres would be submerged by an additional increment of 2,000 feet per second. As only part of this is under cultivation and the larger portion of it of little value a valuation of $10 per acre is not considered high. The total loss due to an additional increment of 2,000 cubic feet per second would be $700,000, which, at 5 per cent, would represent an annual loss of $35,000.

The present flow from Lake Michigan has an appreciable effect on the height of the levees. The flood of 1922 would have been 18 inches lower at Peoria, 6 inches lower at Beardstown, and about 3 inches lower at Grafton. Without this diversion levees could be built lower by these amounts at the points indicated with safety. For the 370 miles of river and cross levees the average effect would be in the neighborhood of 6 inches. This would require about 1,500,000 cubic yards of levee building, which would cost in the vicinity of $300,000 at present prices. At 5 per cent this amounts to $15,000 per year. When all land is leveed which is worth the investment this damage will amount to $30,000 per year.

Additional increments of water from Lake Michigan will work a proportional increase in this amount of damage as indicated below.

TABLE 5.-Damage to levees, Illinois River

WATER-POWER LOSSES AT NIAGARA AND ST. LAWRENCE The diversion of 8,000 cubic feet per second of water at Chicago lessens the flow in the Niagara and St. Lawrence Rivers by the same amount, diminishing permanently the water-power content of these streams. This volume of water entering the drainage canal at Chicago theoretically adds permanently the same amount to the water-power content of the Des Plaines, Illinois, and Mississippi Rivers, though on account of the flat slopes in the lower reaches of the Illinois and in the Mississippi the recoverable water power is much less.

It has been estimated that the amount of water power that can be developed economically between Lake Michigan and the Mississippi River is about 11 horsepower per cubic foot. Existing power installation can produce about 29,100 horsepower as follows: Sanitary district, at Lockport, Ill., 21,000; Public Service Co. of Northern Illinois, at Joliet, 4,500; Northern Illinois Light & Traction, at Marseilles, 3,600. This is equivalent to realizing about 3.5 horsepower per cubic foot of water.

At Niagara Falls a cubic foot of water can produce 29.6 horsepower, while the practical development of power resources of the St. Lawrence River would produce 19.5 horsepower per foot. By way of Niagara and the St. Lawrence a total of 49.1 horsepower per cubic foot may be developed economically as against 11 by way of the Illinois valley, resulting in a net theoretical economic loss of 38.1 horsepower per cubic foot diverted, or for 8,000 cubic feet per second,. a total of 304,800 horsepower.

Under present conditions this is not the actual loss, for but littleof the water power in the St. Lawrence is now being developed,. while that in the Niagara River is only partially used; nor is all the possible energy produced in the Illinois valley. Deducting for the unused energy in the St. Lawrence River (19.6 horsepower per cubic foot per second) and that at Niagara (17 horsepower per cubic foot per second), and adding that unused on the Illinois (7.5 horsepower),. the theoretical loss of 38.1 horsepower is reduced to 9. That this. should not be given much consideration is shown in the next paragraph.

However, the time is not far removed when the power at Niagara will be more economically developed and the practical difference in power values will become the theoretical difference. Furthermore, the development of water power on the St. Lawrence River will come in time, sooner perhaps than might reasonably be expected. As these changes occur the economic loss will increase until it closely approximates the theoretical total of 304,800 horsepower. Any adjustments should keep that fact in mind and make adequate allowance for it.

Assuming the economic value of 1 horsepower year to be $30 and that no increase in amount of diversion will take place, the present loss is 9×8,000 × $30 = $2,160,000 per year, while ultimately, say 50 years hence, it might be 38.1 x 8,000 × $30= $9,344,000 per year. If the diversion were to increase with the population of the sanitary district over the same period, by 1975 it would amount to over 18,000 cubic feet per second, while the power loss would be over $20,000,000 per year. Of course estimates extending over a long period during which prices are so likely to undergo material changes can be nothing more than indicative of the trend of affairs, but they do emphasize the fact that future losses will be large if present methods are adhered to.

SAVINGS EFFECTED BY USE OF DILUTION METHODS

On page 14 it was shown that the total cost of the dilution project to date amounted to $74,313,699.65, or, in round numbers, $74,000,000. The population of the sanitary district is now about 3,213,000, while the human equivalent of the industrial wastes is about 1,560,000. The pollution is therefore equivalent to that produced by 4,773,000. As the sewage of 113,000 people is now being treated by processes other than dilution, the equivalent population taken care of by the dilution project is 4,660,000. The per capita cost of the dilution process is therefore $15.88.

The future program of treatment as proposed by the sanitary district calls for completion of plants that will treat the sewage (by other methods than dilution) of a total population of 4,252,000 by 1945. This will reduce the population whose sewage is handled by dilution alone to 2,531,000. Their own estimate for the cost of this project, exclusive of miscellaneous items which have no bearing on sewage treatment, is about $116,000,000. Reduced to a per capita basis this becomes $27.30. As these estimates for future work are based on present-day prices, while the completed works were practically all built prior to 1910 when prices were much lower than they are now, per capita costs can not be compared properly unless reduced to the same basis of costs.

At the present writing construction costs are over 200 per cent of what they were before 1913, but as it is believed that conditions are somewhat abnormal and will improve in the near future, for comparative purposes it would be better to use 175 per cent. One hundred seventy-five per cent of $15.88 is $27.79. From this it can be seen that Chicago has paid more per capita for its sewage treatment by dilution than it proposes to pay for other methods in the future.

Of course it will be said in answer to this that the main drainage canal and its accessories will be important parts of the new works and therefore should be charged against them in any such comparison as this. On the other hand, the old Illinois and Michigan Canal, with its discharge capacity of over 1,000 cubic feet per second, would have sufficed to carry off the effluent from treatment works with but little if any additional expense. The present volume of Chicago sewage is estimated to be in the neighborhood of 1,000 cubic feet per second. The excessive consumption of water in the city of Chicago is largely responsible for this volume of sewage. Metering the water supply will reduce the amount of consumption and consequently the volume of sewage. (See Part V.) It is safe to assume that the present volume of sewage would not be over 600 cubic feet per second if the water supply were metered.

Had Chicago, in 1890, started metering her water supply, installed filtration plants, and adopted sewage treatment by artificial processes instead of by dilution, the expense to the community would have been no greater and results produced would have been equally efficient.

The operating costs of the new treatment plants will be in the neighborhood of $4,000,000 a year, according to the estimates of the engineers for the sanitary district. This will be at the rate of about $1 per capita. The present operating costs, dilution methods being considered, are about $0.70 per capita, a difference of $0.30 per capita in favor of the dilution method of disposal. As will be explained later, the average annual saving in operation of pumping plants for water supply will amount to $5,000,000 if universal metering is resorted to. As this covers a future period, with larger populations involved, the saving at the present time would be somewhat less, but more than enough to compensate for the difference of $0.30 per capita between the costs of dilution methods and those proposed.

In computing the present value of the works forming the dilution system the cost of installing treatment plants at $27.30 per capita will be used. The main channel and accessories having a capacity of 10,000 cubic feet per second, enough water may be diverted to dilute the sewage of 5,745,000 people-assuming a dilution of 1.74 cubic feet per second per sewage of 1,000 people. (See Part IV.)