(NEW YORK) -- Important bodies of water that supply water to populated regions in the Northeast have dried up due to drought conditions in recent months, according to experts.
Water levels at reservoirs in the region have decreased to the point of concern for water supply managers, hydrologists told ABC News.
Over the past three months, there has been a significant lack of precipitation all over the Northeast, Elizabeth Carter, an assistant professor in the Civil and Environmental Engineering Department at Syracuse University, told ABC News.
Data from the U.S. Geological Survey shows rivers and channels throughout the Northeast region are at extremely low levels. Fall is the time of year when rivers and streams are typically near full capacity, refilling from the summer months when usage is at the all-time high, said Brian Rahm, director of the New York State Water Resources Institute at Cornell University.
"This would be a low level that we would expect to see less than once every 100 years," Carter said.
The heavy rain soaking the Northeast on Thursday will help ease the drought but will not be enough to refill the reservoirs to normal levels, experts say.
Current water data from the USGS show extremely low streamflow conditions, which indicate that the groundwater table has dropped in tandem to the lack of precipitation -- as the groundwater continues to flow out of perennial streams without any replenishment, Carter said.
Water levels in the Wanaque Reservoir in New Jersey, the second-largest in the state with a capacity of 29 billion gallons, is currently at just 44% capacity, according to the USGS. Before-and-after satellite images show how much the body of water has shrunk since November 2023. Surface levels are currently at 16 feet below where it was at this time last year.
In New York City, the water system was at 63% capacity as of Monday, according to the city.
But the Northeast is home to many small towns that manage their own water. Water levels in smaller reservoirs have likely decreased at much more dramatic rates than the larger ones, Anita Milman, a professor in the Department of Environmental Conservation at the University of Massachusetts Amherst, told ABC News. Smaller reservoirs are more severely impacted by the drought, Gardner Bent, information specialist at the USGS New England Water Science Center, told ABC News.
The Cambridge Reservoir in Massachusetts, which has a capacity of 1.5 billion gallons, is below 50% capacity, Bent said.
"Those are the places that I would be the most concerned about, because they have a limited amount of water and storage, and they need that water," she said.
Reservoirs all over the U.S. are experiencing declines, according to a paper published in August in Geophysical Research Letters. Major reservoirs -- including the Lake Mead and Lake Powell, the largest in the U.S. -- are experiencing longer, more severe and more variable periods of low storage than several decades ago, the study, led by the USGS, found.
The Northeast has been in a rain deficit since September. Since last week, drought conditions have continued to worsen across New Jersey, with 100% of the state now in a severe drought, and extreme drought conditions expanding across parts of South Jersey, according to the U.S. Drought Monitor.
The state of New Jersey issued a drought warning for the first time since 2016. This is also the first time a drought warning has been issued for New York City since 2002, according to officials.
Will the Northeast receive more rain in the coming weeks?
Looking ahead, NOAA’s Climate Prediction Center says that odds favor above average precipitation for a large swath of the nation through the end of November, including much of the Plains, the Midwest, and East Coast.
In the Northeast, a much-needed stretch of wet weather began impacting the region on Wednesday night and is expected to continue through Friday.
A large swath of the region, including northern New Jersey, New York City, and New York's Hudson Valley, is expected to receive more than 2 inches of rain over that time.
The soaking rain will effectively end the elevated wildfire danger that has been plaguing much of the region in recent weeks.
For cities like New York and Newark, New Jersey, more than 2 inches of rain would completely erase the rainfall deficit for November and cut the current fall season deficit by around 25%.
However, even after this drenching rainfall, much of the Northeast, including the I-95 corridor, would still need to receive several inches of rain in the coming weeks to significantly improve drought conditions. More than a half-foot of rain would need to fall to completely wipe out the current rainfall deficit that many large cities have been experiencing since September.
Recent rounds of significant precipitation have been alleviating drought conditions across portions of the Plains, Midwest and South over the past seven days. For the contiguous U.S., overall drought coverage decreased from 49.84% to 45.48% week over week, according to an update released on Thursday by the U.S. Drought Monitor. The soaking rain currently sweeping across the Northeast will not be factored into the drought monitor until next week's update.
But it will take months for dry conditions to recuperate, the experts said.
"We're really looking for sustained seasonal precipitation to slowly bring these systems back to, you know, to where we expect them to be," Rahm said.
The current drought situation took months to evolve, and it will likely take several more rounds of significant rainfall over the span of weeks or even months to completely eliminate the widespread drought in the region, Bent said.
What will happen if drought conditions don't improve?
Every state in the U.S. has a drought contingency plan in the event that water levels dwindle to alarming levels, which include steps to deal with increasingly restricted supply availability, the experts said. Once drought conditions worsen to a "warning," water managers begin to implement actions that wouldn't necessarily be triggered by a "watch," Rahm said.
If dry conditions persist in the Northeast, the first step will be voluntary restrictions, Milman said. Then, legal mandates would be issued to reduce water use, she added.
One saving grace for the extremely dry conditions in the Northeast is that the fall is not the time of year when water usage is at its highest, the experts said. During the summer, people are often expending a lot of water for their lawns and gardens, but those plants will soon go into dormant mode, Milman said.
Conversely, it means that drought protection measures that are intended to be implemented during the summer, when all levels are low, may not make as much of a difference, Milman said. Outdoor water and the times people are permitted to water their lawns -- when sunlight isn't at its highest -- are typically targeted first.
"We recognize that indoor water use is essential for most human needs," Milman said.
The Northeast is typically considered a "water rich" region, and the infrastructure is set up based on expectations of average seasonal precipitation, Rahm said.
"The infrastructure that we have established to use that water is reliant -- in some ways -- on our expectations of how that water will fall," he said.
In other countries with arid climates, cutbacks can involve rationing, such as differing segments of a town getting a certain amount of water pressure during certain times a week, which has proved successful, Milman said.
"I've never seen this in the eastern United States," she said. "... But this is what other countries do all the time when they don't have enough supply."