Recent rains have eased concerns about possible drought conditions in some areas of northern and eastern New Jersey but stream-flow remains sharply below normal in most localities, and officials are warning that they may call for voluntary water-conservation measures if the latest uptick in rainfall is not sustained.
Data from the Department of Environmental Protection show that precipitation in some parts of Sussex, Passaic, and Warren Counties was as much as 50 percent below normal in the 90 days to July 14, while that in Ocean and Monmouth Counties was between 11 percent and 25 percent less than the average for this time of year.
Sussex County, for example, had only 9.2 inches of rain from mid-April to mid-July, or 3.6 inches less than normal, the DEP data showed.
The shortage of rain has been drying up streams that are classified as “extremely dry” in four of the six regions covered by the DEP’s regular bulletin on drinking water supply, most recently published on July 10. In five of the six regions, rainfall over the past 90 days was judged to be moderately to severely dry. The only region that has seen precipitation at or above normal levels is the coastal south, including Cumberland and Cape May counties.
“Scant rainfall, particularly across New Jersey’s northern tier, is degrading the drinking water supply indicators tracked by the NJDEP,” the department said in a commentary on its website. “While there are no adverse impacts on drinking water supplies at this time, the constrained indicators point to potential trouble ahead in terms of a developing water-supply drought if conditions persist.”
The department said that its water officials are closely monitoring conditions and planning for a possible Drought Watch — in which people are asked to make cuts in water use such as lawn watering — if necessary.
State Climatologist David Robinson of Rutgers University said the state was “in better shape water wise” by mid-July than it was at the start of the month, thanks to rains that have slowed the drying out of soils, raised river levels, and reduced the drawdown on reservoirs.
“What was a continually deteriorating situation throughout June was at least temporarily brought to a halt over much of the state with the rainfall we’ve seen in the last two weeks,” Robinson said.
But the rains have not fallen uniformly across the state, leaving an arc from Gloucester to Ocean Counties relatively dry while Atlantic, Cape May, and Cumberland Counties have had good rainfall, and northern New Jersey has seen a “hit and miss” pattern of precipitation, he said.
Despite the rains, it’s difficult to significantly boost river flow or groundwater during the summer because high temperatures increase evaporation and dry soils absorb any rainfall before it reaches the rivers.
Still, the recent rains have helped reservoir levels, which had been on a sharp decline, Robinson said. “It’s still declining, and that’s natural for this time of year, but it was declining at a faster pace,” he said.
While the overall situation has improved somewhat, water supplies are by no means abundant, and could resume a downward path unless rainfall is sustained.
“There is little margin for error over the remainder of the summer, and any prolonged period of dry weather and hot temperatures could send conditions into a tailspin,” he said.
Larry Hajna, a DEP spokesman, noted that current and projected water levels at some North Jersey reservoirs are moving below their historical averages as the current lack of rainfall is beginning to show.
A graph showing the combined level of 13 Northeast reservoirs, for example, projects their overall level will be around 85 percent of capacity by May 2017, down from a historical average of about 95 percent.
“If we don’t get sufficient rainfall to bring up the level of the rivers and streams that recharge the aquifers, it could become a problem later in the summer,” Hajna said.
In March, the DEP lifted a Drought Watch that it declared last September with the aim of encouraging residents to take voluntary water-saving measures like cutting back on watering their lawns, and using appliances such as dishwashers and washing machines sparingly.
“It’s important for people to understand the importance of conservation,” Hajna said. “A lot of that water is being used to water lawns. Unfortunately, a lot of people have their sprinklers on timers, and they just don’t even think about it. They should take them off the timers or readjust the timers so that the lawns are getting what they need but not so much that it’s wasting water.”
Rather than using a hose to clean your sidewalk, sweep it with a broom, and only run the dishwasher when it’s full, Hajna recommended.
Amy McHugh, a hydrologist at the U.S. Geological Survey in Lawrenceville, said the current dry conditions differ from last year’s by occurring earlier in the year, suggesting that the year as a whole could be drier.
“Last year was dry but it started later in the year,” she said. “It seems like we are dry earlier this year than we were in 2015.”