UPPER PASSAIC BASIN.
Millington reservoir.—There is an area of swamp land, comprising a part of the drainage area of upper Passaic River above Millington, which is known as Great Passaic Swamp. It is bounded on the south by a long, narrow trap ridge known as Long Hill, the summit of which ranges from 400 to 500 feet in elevation, or roughly 200 feet above the border of this swamp. To the northwest the land rises gradually toward Trowbridge Mountains, while to the northeast is the terminal moraine. The outlet of Passaic River at Millington is by a narrow gorge, which offers natural facilities for the erection of a dam.
The whole situation is exceptionally good, and the surface of a reservoir might be fixed at any elevation between 240 and 300 feet above sea level. With the surface of the reservoir at 300 feet a dam 1,600 feet long and 90 feet high would be required. This lake would have an area of 28.46 square miles. The drainage area above Millington has, however, an area of only 53.6 square miles, and the proposed reservoir would therefore cover more than half of this. Therefore the conservation of so large a quantity of water would not be necessary nor advisable, unless the beautifying of the surrounding country were an object to be taken into consideration, which might be profitable.
A better project, however, would be to construct a dam at Millington 900 feet long and 50 feet high, the crest being about 260 feet above sea level. There would be formed a lake with an area of 19.41 square miles, and a capacity of 1,477,600,000 cubic feet, equal to 9.864 feet on the drainage area. This project is too great for the necessities here presented, and would not be wisely considered unless it were found advantageous to improve the country generally as a place of suburban residence. The land which would be flooded with the reservoir crest at 260 feet is of a wet, swampy character, and its value for agricultural purposes is somewhat doubtful. Such construction would involve the flooding of 13 miles of road, which, however, would not involve a great loss of invested capital, as the roads generally are of a poor character.
A second alternative would involve the construction of a dam across the Millington gorge, 550 feet long and 30 feet high, raising the water to 240 feet above sea level and creating a lake of 14.40 square miles. This would conserve 4,026,000,000 cubic feet, equal to 2.69 feet on the drainage area. This would be ample for flood purposes and would still afford a large impounded area, as the drawing off of an amount equal to 10 or even 15 inches on the watershed would not reduce the size of the lake to any great extent.
The whole project here presented involves few difficulties, and as the drainage area above is of small extent, the mere question of conserving the flood waters could be met without great difficulty. The natural advantages, however, are so great and the land included within Great Passaic Swamp is of so little value that the surrounding country would be improved and beautified by the construction of such a reservoir. The opportunity for varying the character of the reservoir to meet the ideas of those interested seems unexampled, and as a whole it presents an extremely interesting field which may be profitably exploited.
SADDLE RIVER.
This stream has been described in the report on the flood of 1902, already referred to. It contributes a large amount of water to the main artery of the Passaic below Dundee dam, and as the river channel at that point is overburdened under the present conditions because of lack of slope and numerous catchments, together with what is known as the Wallington Bend, it increases very materially the damage caused by floods.
The most effectual remedy in the case of Saddle River floods is that of construction of flood catchments. No studies have been made of the situation in the Saddle River drainage area, but a superficial inspection of the basin shows that opportunities for the construction of flood-catchment reservoirs are not numerous.
SUMMARY OF FLOOD-CATCHMENT PROJECTS.