Earth Matters: Essential information about L.I.’s aquifer systems

Here is some essential information about Long Island’s aquifer systems:

1. The groundwater stored in the aquifers beneath Long Island is a public resource that must be properly managed and continually monitored in order to assure that the public’s health, safety, and welfare is protected and that the resource itself is preserved in the most sustainable manner possible. Presently, this level of attention is not being given to the groundwater.

2. Unlimited drinking water is not guaranteed to the residents of Long Island. Unlike other parts of New York state and New York City, the residents of Long Island do not have access to drinkable surface water, and the New York City water supply is not an option for meeting future water needs, especially for Nassau County.

3. In some parts of Nassau County, water withdrawals have exceeded sustainable levels of pumpage for some years. Since the early 1990s, total water loss from the aquifer systems beneath Nassau County has regularly exceeded annual recharge.

This practice results in problems such as saltwater intrusion, the reduced stream flow, and the spread of contamination plumes into deeper levels of the aquifers where most drinking water is withdrawn.

4. As of 2017, Long Island had the largest number of state and federal Superfund sites — 258 — in New York state.

Nassau County has the largest concentration of contaminated sites of any county in New York state with over 154 listed sites. Remediation of these sites is lagging years behind what is acceptable.

Many sites have been known for decades and progress on cleanup is slow. Each year that a site fails to be cleaned up, the groundwater plumes can spread further and deeper from the original source, polluting millions of gallons of additional groundwater.

Timely attention to these sites is grossly inadequate. Even when the land at a contaminated site is cleaned up, the contaminated groundwater plume caused by the site may be left in place, without cleanup. The plume may then continue to spread through the groundwater system.

During clean-up operations, the cleaned groundwater may not always be returned to the aquifer system. Instead, it is discharged as wastewater or to coastal waters and does not contribute to groundwater recharge. This needs to change.

5. In Suffolk County, due to the absence of centralized sewering (only 25 percent of Suffolk is sewered), untreated or poorly treated sewage (residential and commercial) is being discharged back into the aquifers. This practice is leading to the growing contamination of shallow groundwater, some of which flows quickly into coastal waters, adding to poor coastal water quality there too.

6. The New York State Department of Environmental Conservation is the state agency responsible for protecting the quality and quantity of Long Island’s groundwater supply. Presently, the agency is unable to meet the needs of Long Island or to provide full scale oversight of this essential resource.

7. The county health departments are responsible for the drinking water quality delivered by water suppliers, but they cannot assume the Department of Environmental Conservation’s responsibilities for overall aquifer management.

8. There are approximately 65 major public water suppliers on Long Island. Their expertise is centered on drinking water production and delivery to the public. It does not extend to regional groundwater management.

9. Unlike 70 percent of New York state, Long Island has no groundwater resource manager with a full-time team of water experts dedicated to the constant monitoring, research and assessment of its groundwater and sole source aquifer system.

10. Groundwater withdrawals for Nassau County have been reported by New York state to be at least 15 percent above what the aquifers can sustainably provide.

This condition has existed for nearly two decades. In January 2017, the New York state DEC directed all public water suppliers on Long Island to reduce summer water withdrawals by 15 percent within three to four years. This is a very positive step bringing water waste under control.

11. The year 2018 is the second of the three-four years that all water suppliers have been given to achieve at least a 15 percent reduction in summer water use by each district. To reach this goal, both the water suppliers and the customers need to fully cooperate in doing their part to avoid water waste and excessive demand.

The main focus of this effort is to control peak summer water use.

12. The state DEC reports it is reviewing all the water conservation plans submitted by public water suppliers. Then suppliers will have to implement their plans and document water demand reductions. Many water suppliers are addressing infrastructure issues first such as water leak detection programs and upgrading and inspecting water meters for water consumption accuracy.

Information provided by Water For Long Island (

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