WHEN DOES A DROUGHT on the Delaware River become official?
Any day now.
Most of the counties that surround the river have been in various stages of drought (as called by the respective states) for several weeks.
The river's drought status is informed by the status of five reservoirs and called by the Delaware River Basin Commission. For a lower basin drought, those reservoirs are Blue Marsh and Beltzville, both of them are in Pennsylvania. Here's what their storage looks like:
It looks as though a lower basin drought might be called fairly soon, with a whole basin drought in a couple of weeks.
Here's the graph of the NYC Delaware reservoirs:
And here's map to see the area affected by a lower basin drought:
And what does that all mean?
Well, the river will be allowed to run lower, without the significant boost it gets from releases from the New York City Department of Environmental Protection's reservoirs. There might be some releases, but not as much as in non-drought times. It also means that NYC's use of its own reservoir water can be restricted. That use of Delaware River water for NYC users is considered an out-of-basin release. That means once the water flows out of a faucet in New York, it doesn't make its way back into the basin but would likely find its way into the New York bay.
Another out-of-basin user is New Jersey via the Delaware and Raritan Canal. Those waters flow into reservoirs in New Jersey but ultimately flow into the Atlantic Ocean.
Many of the users in the basin — industrial and municipal — along the Delaware River will face some sort of cutbacks either voluntary or mandatory, depending on which of six plans the Delaware River Basin Commission uses to go forward.
A network of other reservoirs can get kicked into supplementing the river's flow. Some, like Merrill Creek reservoir in Warren County, New Jersey is a reservoir that the power companies operate, using it to replace whatever river water they use during a drought.
Other reservoirs used for the production of hydroelectric power —like Lake Wallenpaupack in Hawley, Pa., or the Mongaup System in New York that usually release water when it's economically optimum can be called on to release water if the need is great.
After all, this river supplies drinking water for some 17 million people and fulfilling that need is the prime directive, whether those folks are in New York City or in Philadelphia, Pa.
Philadelphia's water intakes are at risk if the salt line (salt water from the ocean) advances too far up stream, which is why there's still an effort, even in drought conditions, to keep waters flowing downstream strongly enough to resist the push of salty ocean water up river.
Here's a map of salt lines past and present:
Finally here's the problem in a nutshell, a comparison of precipitation amounts this year and previously:
The Delaware River Basin Commission's Executive Director Steve Tambini put it succinctly at the commission meeting on Nov. 9:
"Bad weather is good and good weather is bad."
Thanks to Amy Shallcross, manager, Water Resource Operations, DRBC for gathering all the graphs used here for the presentation she made about hydrologic conditions in the basin for the DRBC commission meeting Nov. 9, 2016.
There's lots more here!