Arrangements were made in 1943 to have water samples taken and analyzed frequently from each of the proposed drainage areas or sources of supply. The results of the analyses thus far and reported are given in a supplement to this report. Considering the results of these analyses with respect to quality, aside from hardness, the waters to be used are all of a relatively high degree of purity and are comparable to the present supply from Hemlock and Canadice Lakes. The pronounced bactericidal section of prolonged storage of natural waters in reservoirs is well established. The extensive storage in Hemlock and Canadice Lakes is one of the outstanding reasons for the high degree of purity of the present supply of water to the City of Rochester. Under the proposed program of extension of the system the quantity of storage per unit of supply would remain substantially the same as at present.
There is one characteristic of the water, namely, hardness, which is not materially affected by prolonged storage. Particular attention has therefore been given to the hardness of the water in securing samples for analysis, and the total hardness of the different samples as determined by the soap method, together with the estimated flow in the stream at the time of sampling, has been determined for several hundred samples from the different sources. (These results are given in the Supplement on Water Analysis.)
Unfortunately the analyses thus far made and reported are from samples taken at times when the flow in the streams generally less than 1 csm, whereas most of the water diverted would be at times of much higher flows - 5 to 10 or up to 100 csm or more. Many of the analyses made are therefore more nearly representative of the part of the water from the tributary areas which would be released to the stream than of the water to be diverted and used. The water diverted and used would be mainly from flood flows and melting snow, particularly the latter.
Rainwater and water from melting snow are nearly pure water, with little hardness. It is well known that flood and melting snow runoff consists mostly of surface rather than ground-water and usually contain much less hardness than summer and fall derived chiefly from ground-water. For some drainage basins in New York State the hardness varies inversely as the quantity of flow, while for other areas the hardness decreases about one-half in higher flows.The hardness of water in Hemlock and Canadice Lakes represents mostly the hardness of stored waters derived from flood and spring runoff. A comparison of this hardness as of a given date with that of other streams at the same date, but without storage, has little meaning. For example, the hardness of Springwater Creek at Springwater at times of low water runs up to 100 ppm or more, while the hardness from the effluent from Hemlock Lake at the same time is commonly about 70 ppm. The difference is the result of mixing of hard water from low or summer flows with previously stored soft water from flood flows and melting snow. With the exception of Livonia Creek, waters derived from the proposed additional areas are relatively soft, often softer, in fact, than the effluent from Hemlock Lake, even under summer conditions. Livonia Creek water is objectionably hard in low water but the low flow of this stream, like that of the others, would be released and not used. As already noted, the soft water from Calabogue Creek would be brought into the Livonia Creek drainage basin in connection with the second stage of the project. The water from the two streams would be thoroughly mixed en route into the Hemlock Reservoir, providing an in fluent to the reservoir from these sources having a hardness comparable to that of the present Hemlock Lake supply.
It so happens that the softest and best water available to the present system is the flood water from Canadice Lake Outlet. As already shown, a large portion of this flood water is at present wasted. With the proposed new project all this water will be impounded and stored. This will insure water of about the same hardness as at the present upon completion of the First stage of the project, with somewhat softer water when the Second and Third stages of the plan are carried out. The present hardness of the water used ai about 70 ppm, that of Lake Ontario about 140 ppm, and hardness exceeding 100 ppm is generally considered undesirable because of the increased amount of soap required to soften it.
There is only one industrial use of water within the entire area from which the new supply will be derived. This is a milk station at Webster Crossing, located about one-fourth mile from Calabogue Creek. Some treatment of waste from this milk station may be required.