Basic Facts About the Design of the Delaware River Basin Reservoirs

The Upper Delaware River Reservoirs (3)

Water in -There is only one way for water to get into any of the upper three (Cannonsville, Papacton, and Neversink) reservoirs, and that is through natural runoff from precipitation and snowmelt.

Water out - There are, however, three ways, other than evaporation, for the water to get out of the same reservoirs.

1.  When reservoirs are full, over the spillway. In the case of extreme flooding, over the second spillway, the dam itself (in June '06, at Cannonsville, the water flowed over the second spillway at the rate of 1 million+ gallons per minute).

2. Through the release chambers. That is the name given to the release valves under the dam which release water directly into the river from under the dam.

As you may already know, the original design of the dams included release valves which cannot, even when fully open, keep up with normal precipitation/melt runoff rates into the reservoirs. The original thinking was that anything which exceeded the chamber capacity could just flow over the spillway.

3. Outflow valves. These are the valves which control the movement of water out of the reservoir, through an outflow pipe, to a holding reservoir like the Rondout. The Rondout reservoir has its own outflow valve and pipe, through which the water flows, via aqueduct(s) and on to the city, or to be dumped into the Hudson. The Rondout is the first holding reservoir for the Cannonsville, the Papacton and the Neversink reservoirs. After the water flows into the Rondout, it is at the descretion of the NYCDEP water managers as to how much they will allow to flow through the Rondout outflow down the Delaware or Catskill Aqueduct to the city, or to be dumped as excess.

The dispute over the use of the Rondout outflow revolves around whether or not it should be used to it's fullest capacity, 1 billion gallons a day. At that rate, it could successfully control the creation of voids in the upper three reservoirs by allowing the free flow of water to be diverted to the Hudson when the flow is beyond the city's actual water needs.

The NYCDEP position on the use of the Rondout outflow at its maximum is that "it would be a waste of water." Consistent with that mentality, one of their traditional defensive arguments has always been that the only way they will even consider the creation of any kind of safety voids in the reservoirs would be if 'any proposals included a way to recapture the water they would, in their view, be losing.'

Their position is understandable considering that the loss of the water represents, not a loss of drinking water for the city, but somethng they consider to be much more valuable, the loss of their wholesale supply of a product, water, carefully hoarded, which they sell at considerable profit to downstate communities. Those communties re-sell the water, at a profit, and so it is easy to see why everybody at the retail end is quite happy with the status quo.

So, judging by their behavior, it is easily argued the NYCDEP and the DRBC consider profit more important than the safety of the communites and environments below the dams.