Water panel to reconsider possible drought watch amid outlook for more dry weather
A timely rainstorm helped Delaware water experts defer a decision on whether to recommend a drought watch for northern New Castle County this week but they are due to reconsider the issue at the end of the month amid signs that the extended dry spell of recent weeks will resume.
The state’s Water Supply Coordinating Council, a group of state officials, utility executives, and industry representatives, met in emergency session on Monday to discuss asking Governor Jack Markell to call for voluntary water conservation measures under a drought watch.
Such a measure would be the state’s first since 2007, and would follow several weeks of dry weather and high temperatures which have cut stream flows, reduced some reservoir levels, and pushed a salt line up the Christina River as freshwater flows downstream have ebbed.
As rain poured down outside the Kent County administrative building where they were meeting, the officials voted unanimously to wait until their next scheduled meeting on Sept. 29 to decide on any drought-watch action.
Several inches of rain on Sunday and Monday provided some respite to local officials and utility managers, and seemed at least a short-term answer to the meeting that was hastily arranged at the end of last week.
But the underlying water shortage in some areas looks like persisting, according to the weather forecast for the next couple of weeks.
State Climatologist Dan Leathers told the 23 participants at the meeting that the seasonal pattern of scarce rainfall at this time of year looks like applying as usual, and that there’s no real prospect of a bonus downpour from any hurricanes lurking in the Atlantic.
Hurricane Carl, for example, was in mid-Atlantic on Monday afternoon, and didn’t look like it was going to be affecting the U.S. mid-Atlantic region, Leathers said. “The chances of that affecting us are looking less and less all the time,” he said.
Temperatures, whose relatively high levels have contributed to shrinking of streams and reservoirs in recent weeks, were seen continuing in the low- to mid-80s this week, while no further rainfall was forecast for the next six to 10 days, Leathers said on Monday.
“After today’s rain event, it does not look like raining for the next 10 days,” he said. “There is nothing on the horizon that looks like a lot of rainfall any time soon.”
Still, the prospect of continued scarce rainfall does not represent as serious a threat in the fall as it would in the late spring or summer when temperature are higher, Leathers said. “If we were seeing this situation in May, I would be really concerned,” he said.
Officials’ concern was focused on Newark, whose reservoir was 11 feet below its full capacity on Sept. 16, bringing the water body to about 70 percent of capacity, its lowest level since 2007, said Mark Neimeister, Water Operations Superintendent for the City of Newark. At this time of year, the reservoir is normally about five to seven feet below capacity, he said.
Under normal conditions, Newark reservoir water is pumped from White Clay Creek but managers are not permitted to draw from the creek when its flow in the city is below 14 million gallons a day (mgd), which it has averaged since mid-August, explaining the current low level of the reservoir, Neimeister said.
Despite his concerns about the reservoir level, Neimeister said he was satisfied with the council’s decision to put off a decision on whether to recommend a drought watch.
“We got a lot more rain than anticipated,” he said. “We got about an inch and a half in our watershed, and last Friday or Saturday when we were talking about this meeting, they were expecting maybe a quarter-inch of rain.”
Suez Water Delaware, which provides drinking water to about 100,000 people in northern New Castle County, has partially inflated a “tidal capture structure” in the White Clay Creek to deepen the downstream flows, making it easier to draw water into the Suez plant, and to prevent tidal flows approaching its drinking water intake. The structure is located about half a mile downstream from the Suez plant which is at the confluence of the White Clay and Red Clay creeks.
Tom Hubbard, a spokesman for the company, said the creek’s salinity level on Monday was 38 parts per million (ppm) at the structure, and 74 ppm at its drinking water intake. Neither level was close to the 250 ppm set by the state as the maximum level for chlorides in drinking water.
“In this particular situation we’re in right now, the chlorides at our intake and at our tidal capture structure are at a fraction, like 30 percent or less, of any levels that would be of any concern to anyone,” he said.
The chloride level at the mouth of the Christina River at Newport rose to 675 ppm on Sept. 18, but has since declined because of the increased freshwater flow after Monday’s rain. By Tuesday afternoon, the level was 550, said Stefanie Baxter, an associate scientist with the Delaware Geological Survey.
“We hadn’t had any rain in quite a while so the salt front was creeping upstream,” Baxter said. “Unless we have rainfall like we had to push the chlorides back down the river, the chlorides keep creeping up.”
Data from the Delaware Geological Survey, presented to the meeting, showed that water flows on the White Clay Creek at Newark slowed to a 30-day moving average of 14.3 mgd by Sept. 18, below the levels at which a drought watch or a more severe drought warning would be indicated for that location, and only just above the 13 mgd that could indicate a drought emergency, which would impose mandatory water-use restrictions.
In Brandywine Creek, water flow was reported at an average of 72.6 mgd, slightly above its “drought warning” level, while the White Clay Creek at Stanton registered 32.1 mgd, only just above a “drought emergency” level.
But not all locations have been as badly affected, the data showed. At Wilmington Airport, precipitation for the six months to Sept. 18 was only 1.4 inches below normal – well below the “drought watch” level for that site – while the City of Wilmington’s Hoopes Reservoir was 3.8 feet below normal on Sept. 12, a significantly smaller shortfall than the “drought watch” level there.
Some water levels in northern New Castle County were close to those seen in 2007, data showed. For example, the latest average daily flow in the White Clay Creek at Stanton was only slightly higher than the 31 mgd reported for the same period in 2007, while the flow in the Brandywine Creek was lower than that in 2007.
Kent and Sussex Counties were in better shape, showing higher rainfalls and stream flows in the latest period than in 2007.
Council chairman John Barndt, program manager in the division of water at the Department of Natural Resources and Environmental Control, said the meeting could vote for recommending a drought watch; for the DNREC secretary to issue a public appeal for water conservation; or, as it decided, simply agree to do nothing, and wait until the next meeting to make a decision.