“Analyses of water, below and above Lawrence and Lowell, showed no increase in chlorine. The substance can not escape from the water in gaseous form, nor does it deposit in insoluble combination, yet first inspection would lead to a conclusion that no real increase existed. The facts are that the reduction was due to dilution, and not to any destruction or decomposition. Much depends of course upon the size of the stream into which the refuse is thrown. Thus, while into the Merrimack at Lowell, even during the minimum summer flow of 2,100 cubic feet per second, it would be necessary to throw more than 100 tons of solid matter daily in order to increase the amount in the water by one grain to the gallon; another and smaller stream might be hopelessly fouled by a single factory.”
The effects of dilution are shown in the analysis of the Schuylkill River—there being less sewage at Fairmount Dam, the nearest to the outlet, than any point above. It is estimated that 300,000 inhabitants, exclusive of those in Philadelphia, live within the water-shed of this river, less than 150 miles above Philadelphia, the undiluted sewage from these persons amounting annually to 150,000 tons. In addition to this pollution 15,000,000 gallons daily flow from 115 establishments located on the banks, not considering the 57 collieries and 76 anthracite furnaces. Yet with all this contamination the water at Fairmount, chemically considered, is as pure as most sources. The chemists in their report say: “Having now shown that the Schuylkill water is about as good a water as we might wish to find for a large city in its mineral and organic content.
“Since the present water is good enough, we may keep it so, and even improve it by a system of sewage gradually extended up both sides of the river, especially the left bank, above the influence of Monayunk, and by procuring sufficient legislative power to control the escape of sewage or possibly injurious manufacturing residue. The long line of many miles would tend greatly to the purification of the water by aeration, deposition, or abstraction of possibly injurious substances from the water by the time it reached within using distance of the city.”
The increase of solid matter in the Schuylkill has been as follows:
| 1842, | 4,421 grains in 1,000 gallons. |
| 1854, | 6,109 grains in 1,000 gallons. |
| 1862, | 7,040 grains in 1,000 gallons. |
| 1875, | 8,139 grains in 1,000 gallons. |
The recent analysis by Prof. Stuntz of the Ohio River, also shows the effects of dilution. (The results express the number of pounds of sewage in one million gallons.)
| GENERAL CONDITION LBS. | WORST CONDITION LBS. | GENERAL AVERAGE LBS. | |
| At pumping works, | 1.81 | 11.39 | 4.18 |
| At mouth Eggleston Avenue sewer, | 4.41 | 17.91 | 11.16 |
| At Storrs and Lower River, | 1.96 | 10.00 | 5.94 |
Although increased by the whole sewage of the city in addition to Licking River, Covington, and steamboat contamination, the proportion of sewage at Storrs in its worst condition is chemically shown to be little better than at the pumping works.