698 



NEW YORK STATE MUSEUM 



Just before entering New York State the stream enters a broad, 

 flat valley, extending to Phillipsburg, and varying from one to 

 five miles in width. The floor of this valley is flat, both longi- 

 tudinally and transversely, with its slope in the direction of the 

 river so slight that the valley is usually flooded during the spring, 

 although later in the season the water drains from the flats 

 through the river channel, as well as through several artificial 

 drainage ditches. 



The valley consists of high hills with steep sides. The hills 

 on the west are slaty, slightly covered with soil, while the hills 

 on the east are of granite, marble and limestone. The bottom of 

 the valley is underlaid with calciferous sandstone, generally 

 covered with a few feet of black soil on top of the detritus with 

 which the valley is filled. The geologic structure indicates that 

 there is very little underground flow above Phillipsburg, although 

 Mr Freeman in his report to the Comptroller, also made in 1900, 

 expresses a different opinion. In his view there is a good deal 

 of doubt whether the Wallkill reservoir can be made safe, because 

 of the large leakage from the sides. The writer does not share 

 Mr Freeman's apprehensions, although in the absence of 

 thorough examinations the question is an open one. About 25 

 per cent of the valley is wooded. 



The water of the reservoir on the Wallkill would be as soft and 

 colorless as the Croton water. This conclusion is based on experi- 

 ments and analyses and on a study of the ground and surface flow 

 of the streams. 



It is proposed to erect a dam at Phillipsburg which will im- 

 pound the waters of the river and flood the valley from twenty to 

 thirty feet in depth. The general elevation is about 390 feet above 

 sea level. If the water level be raised to 410, sufficient storage will 

 be provided for a daily draft of 250,000,000 gallons by drawing the 

 water in the reservoir down 5 feet. The area of the catchment 

 above Phillipsburg is 465 square miles. The area submerged at 

 elevation 405 is 49 square miles, and at elevation 410 it is 51 

 square miles. Hence, only about 5 per cent of the area would be 

 exposed on drawing the reservoir, enough to give a yield of 250,- 

 000,000 gallons daily. The amount of water impounded would be 

 approximately 200,000,000,000 gallons (26,700,000,000 cubic feet) 

 of which .V,0()0,000,000 gallons (7,100,000,000 cubic feet) would 



