Why the salt water line in the Delaware River is creeping upstream

The salt line has moved from Wilmington to near the Phila Airport. (Salt line shown is for illustration purposes and does not reflect the exact location) Image by Alan Tu

The salt line has moved from Wilmington to near the Phila Airport. (Salt line shown is for illustration purposes and does not reflect the exact location) Image by Alan Tu

Water managers for the Delaware River Basin sought public input on Wednesday on whether to impose a drought emergency in parts of New Jersey and three other states in response to a prolonged shortage of rainfall.

The Delaware River Basin Commission, which regulates water supply in the basin portions of New Jersey, New York, Pennsylvania, and Delaware, is considering drawing on additional reservoirs after scant rainfall in recent months has cut the river flow and allowed salty water from the Delaware Bay to creep closer to drinking water intakes at Delran and Philadelphia.

Amy Shallcross, the DRBC’s manager of Water Resource Operations, told a public meeting at Washington Crossing, PA, that the so-called salt line in the river has risen to River Mile 88 near Philadelphia International Airport, its second-highest level since the basin’s “drought of record” in 1963. The front has risen three miles since October 20, when it was 13 miles farther upstream than is normal for this time of year.

Although the front is still 22 miles downstream from the drinking water intakes at River Mile 110, the DRBC has been releasing water from two reservoirs in Pennsylvania in an effort to boost downstream flow and keep pressure on the salt front.

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But their ability to maintain the desired volume of water flowing down the river is constrained by the continued dry spell that has depleted the water level in the two reservoirs and led to drought warnings being issued separately by state authorities for many counties on both sides of the river.

At the Beltzville reservoir in Pennsylvania, the water level is 68 percent below capacity, and beneath a drought warning line, Shalcross said.

Any decision to declare a drought emergency would give DRBC additional authority to store and release water from private, state, and federally owned reservoirs. One option would be to ask the U.S. Army Corps of Engineers to release water from a reservoir that is normally used only for flood control, said Clarke Rupert, a spokesman for DRBC.

Although Wednesday’s rain across the region offered some respite to the dry spell of recent months, Shalcross said it would make little difference to the low water levels in the river or to the reservoirs that have been augmenting its flow. And she said there is little rain in the forecast.

“I don’t think we will get a lot of improvement in the basin beyond today’s rain,” she said.

Precipitation in the Lower Basin, downstream of Montague, NJ, is now 20 percent to 25 percent below normal for the year to date, and the 30-day outlook is “a lot scarier” at 50 percent to 75 percent below normal, Shallcross told the meeting.

Beyond that, the 30-day forecast from the National Oceanic and Atmospheric Administration is for below-normal rainfall and above-normal temperatures, she said.

Despite the expectations of little new rainfall, DRBC Executive Director Steve Tambini said there are no immediate plans to declare a drought emergency, and that the commissioners don’t plan to meet to review the situation until December 14.

A drought emergency would be triggered by reservoir levels, the weather forecast, and the status of the salt front. “Our objective is to make sure we’ve got enough water in storage to repel the salt front,” Tambini said, in an interview. By contrast, state authorities look at a broader range of indicators including groundwater levels and stream flow in deciding whether to declare drought watches or warnings.

“At this point, the salt front is well below the intakes,” Tambini said.

Shallcross urged residents to cut back on watering their lawns, even if that means the grass turns brown. “Brown is the new green,” she said.

Doug O’Malley, director of Environment New Jersey, urged the DRBC to declare a drought emergency, and predicted that aberrations from normal weather patterns will occur more often in response to climate change.

“In the future, we will see more and more events like this, and the ramifications for the watershed and the DRBC are immense,” he told the meeting.


NJ Spotlight, an independent online news service on issues critical to New Jersey, makes its in-depth reporting available to NewsWorks.

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