Depleted Reservoirs Prompt Official Drought Watch for Delaware River Basin
With no end in sight to extended dry spell, regulators take action to compel conservation and to try to keep a ‘salt front’ from threatening drinking water
Water managers for the Delaware River Basin are expected on Wednesday to begin an official drought watch in response to the current extended dry spell, allowing them to impose a series of measures to conserve sharply reduced water reserves.
The Delaware River Basin Commission is to hold a special meeting at its West Trenton headquarters to give formal approval to a plan that would cut the amount of water that’s pumped outside the basin, require power utilities to make up for water losses caused by their cooling operations, and reduce the amount of water that’s released from reservoirs to boost flows in the river. Individuals will also be asked to conserve water.
Unusually little rainfall in the basin states of New Jersey, Pennsylvania, New York and Delaware in recent months has depleted reservoirs, slowed the river, and allowed a line of salty water from the Delaware Bay to move up the river toward drinking water intakes at Philadelphia and Delran, NJ.
The drought has prompted state authorities to declare drought watches or warnings in many counties, and is now leading the interstate regulator to impose its own measures in the hope of conserving scarce water as forecasts continue to indicate no significant rainfall in coming weeks.
Some recent rain has moistened the ground but has not boosted the sluggish river flow because the ground is so dry that it has just soaked up the modest rainfall, said Amy Shallcross, manager of Water Resource Operations at DRBC.
She said that although there is some rain in the forecast, it doesn’t appear likely to ease the drought conditions, and so the DRBC brought forward its drought-watch meeting that had been scheduled for December 14.
“The problem is that you can’t count on that rain coming,” Shallcross said. “We could delay it for a week but if that rain doesn’t come, we are in worse shape. We are trying to be a little bit proactive here.”
A resolution to be considered at Wednesday’s meeting “would empower the commission to provide for the conservation of regional reservoir storage through phased reductions in diversions, reservoir releases and flow objectives for purposes of water supply and flow augmentation in the Delaware River and salinity control in the Delaware River estuary,” the DRBC said in a statement.
The meeting is a procedural requirement to allow the measures to be implemented, Shallcross said. “We’re putting drought operations into effect,” she said.
By declaring a basin-wide drought watch, the DRBC can direct reservoirs to store or release water, and can draw on additional reservoirs. The policy will also allow the regulator to reduce its targets for the rate of river flow, which is measured at Trenton and Montague, NJ.
Officials have already been releasing water from two Pennsylvania reservoirs in an effort to keep downstream pressure on the so-called salt front which has been creeping upstream despite those measures.
With a cut in the flow target allowed by the drought watch, the salt front might move a little further upstream, Shallcross said. But she argued that smaller reservoir releases in the near term would reserve more water that officials could use to repel the salt front in future if the drought persists.
“We do not know how long these conditions will last, and saving water in the reservoirs allows us to repel the salt front for a longer period of time, although it may come a little further upstream,” she said.
The salt front is now at River Mile 89 near Philadelphia International Airport, its highest since October 2005 when it touched River Mile 90, and the second-highest since the drought of record in 1963. The front has risen four miles since mid-October, and is now 19 miles further upstream than it normally is in November.
The front is still 21 miles downstream from the drinking water intakes at River Mile 110 and the latest measures are designed to ensure that the salt stays well away from the intakes.
Water officials are trying to ensure that they have enough water in upstream reservoirs to repel the salt front if it continues to rise, Shallcross reiterated. “Do we let it come up a little bit now in the hope that it we’ll get rain and it will get pushed down or do we have to worry about later on when it’s really high up and we need water to push it down?” she said.
The last DRBC drought watch was in 2010 and only lasted for five days before rain allowed officials to withdraw their measures, Shallcross said. This time, there’s no early relief in sight. “It feels like that’s not what’s going to happen; it feels like it’s going to stay dry and so that’s so we are moving into drought operations,” she said.
David Robinson, New Jersey’s state climatologist, said there’s no sign of enough rain any time soon to erase a drought that has left northern and central New Jersey with only two-thirds of normal precipitation over the last eight months.
Robinson, a professor at Rutgers University, said there is an expectation of some rain in the next two weeks but not enough to make a big difference. “There’s not a significant storm track in the short term,” he said. “But there will be some wet systems coming through. It certainly doesn’t look as if we are going to be shut out of moisture.”
The big precipitation deficit of recent months is unlikely to be made up quickly. “It’s a serious situation,” Robinson said in an interview. “I don’t want to say it’s severe or critical but it’s more than worrisome.”
He said the situation is eased somewhat by the fact that evaporation eases in the cooler winter months, and consumption for lawn watering and by plants, drops off as the winter approaches. But reservoirs are 20 percent below their normal level for this time of year, ground water levels are low, and river flows are sluggish.
Water officials are hoping that winter rains make up the deficit in coming months.
“If we don’t receive adequate precipitation between now and April, it’s going to become a critical situation,” said Robinson.