Rockaway River offers a greater number of available reservoir sites than either of the other highland tributaries of the Passaic. Some of the reservoirs which could be constructed could be used solely as catchment areas to hold back flood waters, while the capacity of others would be so much greater than any single flood run-off that they might serve also as compensating reservoirs. A large dam is now in process of erection at Old Boonton, conserving a considerable amount for the water for the municipal supply of Jersey City. This reservoir can not be depended upon as a flood-catchment area, as it will be the aim of those in authority to maintain the water in it as high as possible. _Powerville reservoir_.--A short distance above Boonton the erection of a comparatively small dam would flood a large, irregular, flat basin having an area of a little more than 4-1/2 square miles and extending up the Rockaway Valley to Rockaway Village, up Beaver Brook to Beech Glen, and north and south for considerable distances. The probable capacity of this reservoir has been estimated, and it is fairly certain that it is considerably more than would be sufficient for flood catchment. Its construction would, moreover, improve the entire valley and be of advantage to many interests. The northern New Jersey flood commission has selected for investigation a reservoir site on Rockaway River at Powerville. By the erection of a dam across the stream at this point, 28 feet in height and 470 feet long, a reservoir 4.6 square miles in area, with a capacity of 1,565,000,000 cubic feet, would be afforded. The drainage area above this point is 114 square miles. The cost of such a reservoir is estimated at $600,000. North from Powerville, near the confines of the proposed Powerville reservoir, there is an available reservoir site along Stony Brook. By the erection of a dam 1,100 feet long and 120 feet high a lake would be formed 645 acres in extent, which would serve as a flood-catchment basin and a compensating reservoir. This reservoir would hold approximately 850,000,000 cubic feet. The construction of a reservoir at this place offers no engineering difficulties, and the project may be regarded as extremely favorable. Dixons Pond, west of Rockaway Valley and northwest of Powerville, is a small sheet of water which lies in a valley which might be flooded to a greater height. By the erection of a dam 450 feet long and 30 feet high a lake of 136 acres would be created, which would form a part of the flood catchment and compensating service. _Longwood Valley reservoir_.--A large storage basin is afforded in Longwood Valley which, if developed to its full extent, would extend from a point about a mile below Lower Longwood 7 miles up the headwaters and reach to about 1-1/2 miles above Petersburg. An alternative proposition is afforded which involves the submerging of less than half this area.