The cost of Mountain View reservoir would be about $3,340,000. Developed for flood catchment with the spillway of the dam at 202 feet above sea level the area of the reservoir would be 13.4 square miles, and the storage capacity 7,200,000,000 cubic feet.
RAMAPO SYSTEM.
Along the Ramapo Valley there are alternative propositions, one of which involves the construction of a dam below Darlington and another across the head of Pompton Lake.
In either case the water might be raised to the 300-foot contour, and if the dam across Pompton Lake were constructed a continuous lake would be formed extending 10-1/2 miles to Hillburn, N. Y. The improvement in either case would be positive, for as the country surrounding is hilly or mountainous it affords excellent opportunity for the location of summer homes and parks, the lake being a potent factor in beautifying the situation and increasing the value of the surrounding region. There are, nevertheless, several things to be taken into consideration, the most important of which are the improvements which have been made by wealthy residents along the valley where it has already been developed as a summer resort.
By the construction of a dam at Darlington 1,100 feet long and 70 feet high, the water would be raised to the 300-foot contour. The reservoir would have a water area of 2,064 acres, and the approximate storage capacity of 2,325,000,000 cubic feet.
A dam across the head of Pompton Lake 2,850 feet long and 100 feet high would raise the surface of the proposed lake to the 300-foot contour. This reservoir would have an area of 6.19 square miles and a capacity of 6,300,000,000 cubic feet, equal to 17.5 inches run-off from the drainage area. Here the measure of safety is wide, and if there were drawn from the lake an amount of water equal to 12 inches on the drainage area there would still be 5.5 inches which could be used for compensating purposes.
The construction of either one of the above-described reservoirs would involve interstate complications, as the 300-foot contour in Ramapo Valley includes a considerable part of the State of New York. This obstacle was deemed insurmountable by the northern New Jersey flood commission, and that commission directed studies to a reservoir which at the time of maximum flood would not back water into New York State to a greater height than it already rises during such floods. The following description is taken from the report of the engineering committee of the flood commission:
An admirable dam site is offered on Ramapo River about 2 miles above Oakland village. The drainage area tributary to this point is about 140 square miles in extent, the country for the most part being quick-spilling and upland. By constructing there a dam 700 feet long and 65 feet high a reservoir with a water surface of 2.8 square miles would be afforded, the flow-line elevation being 280 feet above tide. The capacity of such a reservoir would be 1,768,000,000 cubic feet, equal to about 5.5 inches on the drainage area.
WANAQUE SYSTEM.
Near the headwaters of Wanaque River is Greenwood Lake, a large body of water described in Water-Supply Paper No. 88. Its value as a flood catchment basin is somewhat uncertain, as it is used as a storage feeder for Morris Canal. The surface level of this lake is controlled by gates, which naturally are operated by the canal authorities for the benefit of the canal. Therefore it is the object to store as great a volume of water as possible, and the water falls below the dam crest at the outlet of the lake only when the dam opens in dry seasons and makes it necessary. Under such conditions there is no certainty that storage capacity will be available during the time of a great storm, and in fact Greenwood Lake has been overflowing at the commencement of the storms which caused both of the recent floods.