The final recommendation of the committee involves the consideration of two projects for flood storage, one on Great Piece Meadow and the other above Mountain View on the Pompton. In making such recommendations the committee is of the opinion that it must take into account matters of engineering policy with regard to future needs and contingencies, as well as the bare necessities of the present.
If there were none other than the single problem of prevention the committee would advise the construction of the reservoir on Great Piece Meadow by reason of its smaller probable cost and its equal efficiency. It is plain, however, that there are many important features of public policy involved in the subject at hand. Population in the valley of the Passaic is developing so rapidly that in only a few years the present sources of water supply will be inadequate. The whole subject of water supply for northern New Jersey demands immediate consideration, and it would not be wise to take up the matter of prevention of flood damage in the Passaic without basing the value of every project upon its adaptability for use in future water-supply needs.
By expending $2,600,000 a great reservoir could be constructed upon Great Piece Meadow which could not be adapted for any purposes except to regulate floods; it would stand in season and out of season a huge feature of the valley and entirely useless and inoperative save on the occasion of high water. However great might be the needs of the inhabitants of the Passaic Valley for a conserved water supply, the construction on the meadows, representing an enormous expenditure, would furnish no solution of the problem. It would admit of no enlargement for water-supply storage and would be available for no purpose except flood regulation.
When we consider the Mountain View project, however, we find that as a measure for the prevention of flood damages it fulfills all the requirements and provides in addition all the possibilities and advantages demanded inevitably in the near future. The Mountain View site is an ideal one for the reservoir, and its initial development for flood catchment does not involve the expenditure of a dollar that would be lost in the development of the basin to greater capacities for water supply. From its lowest level, at 202 feet above tide, to its maximum capacity, at a level of 220, there would be no depreciation. Every dollar spent in the initial construction would be effective in the maximum development.
The probable cost of Mountain View reservoir, estimated at $3,340,000, exceeds that of Great Piece by $700,000. It is realized that to many persons this margin may seem very wide. Let us consider briefly just what it really represents.
Suppose, for example, that the Great Piece project is constructed at a cost of $2,600,000. After the elapse of a few years it will be necessary to provide additional storage in the Passaic highlands for water supply or the maintenance of water power. The Mountain View reservoir, or its equivalent in capacity and cost, will then be necessary. The situation will then be as follows: By constructing the Great Piece reservoir in preference to the Mountain View for flood catchment, $700,000 would be saved. We can consider that this amount might be expended to pay a part of the cost of additional conservation above referred to. If, on the other hand, Mountain View had been constructed, there would have been paid on the final cost of conservance the sum of $3,340,000, which, as stated in previous pages, would also have effected flood relief. There would then be the difference between $2,600,000 and $700,000, or $1,900,000, which represents the actual loss which would accrue by reason of the construction of Great Piece reservoir.
The engineering committee, after presenting the merits of both Great Piece Meadow and Mountain View projects, therefore recommends the adoption of the latter in spite of its greater cost, because it is believed that in the end the construction of the Great Piece project would involve an expenditure not warranted by public economy or general expediency.
GENERAL CONCLUSIONS.
1. Great floods in the Passaic Basin arise only after a specially violent precipitation.