The concentration of salt water invading Long Island's deepest and most pristine water source is increasing, but the extent of contamination is unclear because well monitoring stopped in 2010, research from the U.S. Geological Survey shows.
On Nassau County's North Shore, a sampling of data from six wells measuring the Lloyd aquifer showed that concentrations of chloride -- an indication of salt water -- have increased over time.
And on the South Shore, levels at another six wells indicate the beginning of contamination of fresh water, according to research by USGS research hydrologists Frederick Stumm and Anthony Chu.
"The Lloyd aquifer should have nondetectable chloride or very small numbers," said Stumm, who presented the findings recently at a USGS Water Science Symposium at Hofstra University. "You can actually see how it's migrating through the aquifer."
Three aquifers -- the Upper Glacial, Magothy and Lloyd -- serve as Long Island's water sources. The Lloyd is the deepest underground, and many coastal communities on the North and South shores rely on it for drinking water. If salt water intrudes, fresh water becomes tainted and wells unusable.
"It was a big wake-up call," Sarah Meyland, co-director of the Center for Water Resources Management at New York Institute of Technology, said of the new findings. "The Lloyd is the ultimate emergency water supply, and for coastal communities it is the only water supply."
The Lloyd represents a small portion of the water used on Long Island, and of the 42 wells permitted by the state Department of Environmental Conservation, 35 are in Nassau and three are in Suffolk, regional director Peter Scully said.
In Nassau, 4.5 billion gallons are withdrawn yearly from the Lloyd, representing 6.3 percent of the total water withdrawals from Long Island aquifers.
In 2010, the latest year available, 162.5 billion gallons were taken from aquifers, serving more than 2.6 million people, said Meyland, also a member of Water for Long Island, a coalition of groups.
Stumm said the higher chloride levels are from pumping water out for usage. "You're not getting that kind of change naturally," he said.
Reducing stress on supply
While the sampling showed increasing levels, DEC said withdrawals from the Lloyd aquifer have decreased over the years and saltwater intrusion is a slow process that can be as little as a few feet a year.
At its peak, Kings County took 1 billion gallons a year from the aquifer until it stopped pumping in the 1940s, and Queens County used nearly 3 billion gallons of aquifer water before halting pumping in the late 1990s, according to USGS data.
"Many of the pumping stresses have been reduced over the last several decades . . . ," the DEC said in a statement. "And adjustments in pumpage patterns have been made locally where necessary."
The DEC does not compile annual reports on usage. Permits to pull from the Lloyd come with limits based on location and other factors to ensure the resource remains healthy, it said. The last well permitted was in 2004, Scully said.
Stumm said despite the decrease in pumping, the aquifer needs to be watched because "once it's intruded, it's really . . . pretty much a lifetime situation."
To arrive at the findings, Stumm and Chu compared several years of chloride level data at six North Shore monitoring wells, focusing mainly in North Hempstead. They also looked at single-year well data at six sites on the South Shore, including Long Beach and Tobay Beach.
A wedge of seawater estimated to be 5 to 10 feet thick in Bayville in 1992 was estimated to be 75 feet by 2008.
In one monitoring well in Great Neck, chloride concentrations measured 3,375 milligrams per liter in 1993. By 2009, the concentration was 7,000 milligrams per liter. In a Manhasset Neck well, concentrations increased from 28 milligrams per liter in 1998 to 215 milligrams per liter by 2005.
The recommended maximum chloride concentration for drinking water is 250 milligrams per liter. Chloride levels in the Lloyd should measure between 3 and 5 milligrams per liter.
The monitoring wells are separate from public supply wells.
The ever-growing level of chloride is a signal that problems are on the horizon, Chu said.
"If you overpump the resource, it will lower the levels to a point where it causes saltwater intrusion," Stumm said.
In the 1990s, Nassau's Department of Public Works spent $1 million drilling monitoring wells into the Lloyd aquifer to measure for saltwater intrusion. The USGS monitored the data from these wells for years, but the county stopped funding the $170,000-a-year monitoring program in 2010.
USGS relies on grants and partnerships with governmental or nonprofit entities to fund research. Without the money, monitoring stopped.
"In these difficult economic times, municipalities throughout the nation are reallocating funds to critical programs and services that directly benefit their residents," county public works spokesman Mike Martino said in a statement about why the program ended.
Funding to remain dry?
Some sampling continues on the South Shore, but he said there are no plans to look for new funding sources. The county was working on notifying public water suppliers about the USGS research, which the county does not dispute.
Nassau County Legis. Judi Bosworth (D-Great Neck) said she would investigate creating an entity to oversee water supply issues. "When we start talking about that source becoming contaminated . . . we're talking about affecting our future," she said.
Water for Long Island is also pushing to establish an LI Aquifer Management Agency to oversee, manage, study and protect the aquifer system on Long Island. It would be funded by a tax on water usage, estimated to be $3.50 per taxpayer annually, Meyland said.
It's modeled on entities elsewhere in the state that oversee water supplies. "All of the major population centers of New York State are within management commissions," she said. "The only population center that has nothing to oversee their water supply is Long Island."
The group has talked to state and local politicians and is meeting with civic groups. They hope for state legislation to be proposed in 2013.
"There's nobody monitoring these things," Assemb. Robert Sweeney (D-Lindenhurst) said. "We find out as the problems come along."
State regulations require that public and private water suppliers screen for contaminants.
Dennis Kelleher, president of H2M Water in Melville and public relations chair for Long Island Water Conference, which represents water supply and management groups, said water suppliers monitor for salt water as part of routine screenings, though it varies by district and conditions.
"I don't think there's a problem with the amount of water we're pumping out of Nassau County," he said.
Groups pick up monitoring
The Port Washington Water District, for instance, has 12 wells, including two in the Lloyd. Three wells are located off the peninsula because the district was concerned about saltwater intrusion. "We are watching the modeling," superintendent Italo Vacchio said.
While the county has stopped monitoring for saltwater intrusion, other groups are trying to fill the void.
Residents for a More Beautiful Port Washington in North Hempstead formed the Peninsula Aquifer Committee in 2000 to look at water quality issues. The group includes the Port Washington and Sands Point water districts, the Town of North Hempstead and the five area villages. They pay for monthly monitoring of chloride levels, which costs about $40,000 to $50,000 a year. USGS covers some of the costs and does the monitoring, said Mindy Germain, executive director of Residents for a More Beautiful Port Washington.
"Saltwater intrusion is a very big issue for us," Germain said. "We hope the county will be able to restore funding. In the meantime, these small groups have stepped up."
Stumm and Chu say the data are an early warning. They favor studying the area's water supply and needs to come up with a management plan.
"We can figure out what is sustainable," Stumm said. "It's everybody's problem."