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4,500 square miles above Mechanicville. Since the run-off in this forest covered mountainous region is fully half the rain fall, this six inches of extra rain fall would add at least three inches to the run-off. There is no reason for thinking that the ratio of run-off to rain fall would be less, indeed the contrary is true and so we may expect 15 per cent more run-off per square mile on the Sacandaga than on the Hudson, and since our mass curves have shown that a draft equivalent to twenty-two inches run-off may be relied upon from the Mechanicville records for the entire upper Hudson, we are justified in expecting 22+15 per cent. 25.3 inches run-off from the Sacandaga, or about 1,950 cubic feet per second, instead of the 1,700 derived from the Mechanicville curve.

The Esopus experience quoted on page 118 in comparison with the Croton, indicates a much larger rain fall and run-off from the mountains than from the lowlands, and long term records are more likely to increase than to diminish this figure of 1,950 cubic feet per second of flow constantly available from the Sacandaga reservoir as proposed.

YIELD OF WATER POWER FROM THE ESTIMATED FLOW FROM SACANDAGA RESERVOIR.

Estimating the Sacandaga reservoir yield conservatively at 1,700 cubic feet per second to allow for lack of precision in gagings and for more severe droughts and calling the extreme average net available fall 185 feet and the turbine efficiency 75 per cent. we obtain:

or, say,.

1,700x62.4x185x75%
550

r mechanical horse power on turbine =26,761 shafts 24 hours per day, 7 days in the week, throughout the dryest year.

.25,000 horse power.

Should we thus take all elements at the maximum, the flow at 1,900, the working fall at 185 and the turbine efficiency at 80 per cent. the 24-hour 7 day average of power from the Sacandaga becomes about 30,000 net horse power on the turbine shaft instead of the 25,000 as previously figured, and this 30,000 horse power 24 hours 7 days in the week is the most probable figure for the complete Sacandaga development, and under use with a 40 per cent. load factor would generate at 95 per cent. efficiency 53,200 kilowatts, which at 85 per cent. efficiency in transformation and transmission would deliver in ordinary working hours a maximum of 60,500 horse power to the consumer, exclusive of the power added by this stored water at the sites all along the Hudson from Palmers Falls to Troy. This gives the measure of the new power plant to be planned.

INCREASE OF POWER AT THE PRESENT HUDSON RIVER PLANTS DUE TO THE DISCHARGE OF STORAGE FROM THE SACANDAGA RESERVOIR.

As has been already stated, this reservoir may be used according to two different methods for the benefit of the power sites upon the Hudson river. In the early years or before the long tunnel and power plant near Hadley are built, the storage can be all used for reinforcing the flow of the Hudson, holding it all back in those months when water in the main river is plenty

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and changing the rate of discharge from the Sacandaga from day to day, so as to maintain the Hudson flow at a uniform rate at some mean location such as Spier's Falls, or perhaps at Mechanicville if navigation interests are paramount.

While I believe the greatest good would be found by selecting some locality farther upstream than Mechanicville as the point of control, thus regarding the water power as the paramount interest, I have based the following computation upon maintaining the flow constant at Mechanicville, as was done in the earlier reports of the State Engineer.

The first step in this computation is the determination of the average flow in the Hudson month by month, and much better results are obtained by first arranging the months for taking the average in their order of dryness instead of in their calendar order.

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