New York State Department of Health Source Water Assessment Program …

New York State Department of Health
Source Water Assessment Program


Long Island Source Water Assessment Executive Summary
The 1996 Safe Drinking Water Act amendments        The purpose of the assessments
encouraged states to develop a Source Water
                                                   The purpose of the source water assessments is to estimate
Assessment Program to assess all sources of
                                                   the potential for contamination of public water supplies. The
water used by public drinking water systems.
                                                   assessments are designed to help identify priorities for public
The New York State Health Department has           water supply protection.
undertaken the task of assessing public water
supply sources in New York State. The State        Individual assessments should not be used to draw any
Health Department gathered input from public       conclusions about the quality of water delivered to area
and private interests to develop its statewide     residents. Drinking water delivered by public water supply
Source Water Assessment Program Plan. This         systems are closely monitored by local health departments to
plan was approved by the United States             meet all drinking water quality standards. In many cases, the
Environmental Protection Agency in November        potential for contamination does not result in any actual source
1999 with the goal of being completed by May       water contamination. In cases where contamination has
2003.                                              occurred, the water may be treated to meet applicable water
                                                   quality standards.
Because of Long Island's distinct setting, the
New York State Department of Health worked         Detailed information about a specific community (residential)
with the Nassau and Suffolk County Health          water supply is available from the water supplier's Annual
Departments and other interested parties to        Water Quality Report. Information about noncommunity
develop a methodology for source water             (nonresidential) public water supplies is available from the
assessment specific for this area.                 local health department.
Long Island relies on ground water as a source
                                                   Scope of work
of drinking water and the ground water system
is classified as a sole-source aquifer. In         The source water assessments for Long Island consist of
Nassau and Suffolk Counties, there are over        three main components:
500 public water systems that rely on more         1. Delineating well recharge areas using computer-based,
than 1,500 different ground water source wells.       three-dimensional models. Additional information was
The regional aquifer systems on Long Island           incorporated into existing computer models developed for
have been extensively investigated and as-            many parts of the Long Island regional aquifer system.
sessed. Extensive ground water resource               These models help predict ground water flow to each
management and protection efforts have evolved        public water supply and throughout the entire aquifer
related to Long Island's unique regional setting      system. This information provides pathway information
and hydrogeological characteristics.                  about the origins of the source water in each well and the
                                                      likelihood for contaminants to affect a particular public
The State Health Department hired a contractor
                                                      water supply well.
(Camp Dresser & McKee) to complete the
source water assessments for public water          2. Identifying sources of potential contamination.
systems in Nassau and Suffolk counties using          Specific facilities within each well's recharge area that
the methodology developed for the region. The         could potentially contaminate the ground water were
contractor prepared a draft Source Water              identified, such as landfills and Superfund sites. Land use
Assessment Summary Report and draft source            patterns were also reviewed to determine the likelihood of
water assessments for each public water               contamination.
supply well on Long Island. Drafts of these        3. Evaluating susceptibility to contamination. The source
individual reports are being reviewed by water        water assessments combine the information about how
suppliers. The final Summary Report will be           ground water travels throughout the aquifer system with
available by the end of May 2003. A summary           the information about sources of potential contamination to
of the assessment of each individual well will        determine the overall susceptibility of public water supply
be included in the water supplier's Annual            wells to contamination. Public water supply sources are
Water Quality Report beginning in 2004.               rated on a scale of low, medium, medium-high, high and
                                                      very high in terms of their susceptibility to contamination.
Summary of results                                        that remains there. In Suffolk County, where
The susceptibility of a public water supply well to       significant tracts of agricultural lands exist, about 10
contamination depends on:                                 percent of the public water supply wells were rated
                                                          as medium-high or greater for susceptibility to
1) the presence of the potential sources of contami-
                                                          pesticides. Most of these wells are located in
    nation within the well's recharge area; and
                                                          agricultural areas in central Suffolk County, or on
2) the likelihood that the contaminant can travel         the north fork of Long Island.
    through the environment to reach the well.
                                                          VOCs. Due to the extensive distribution of potential
These factors are combined to estimate the suscep-        sources of VOCs in the highly developed areas of
tibility of each well.                                    Nassau County, more than 75 percent of public
Susceptibility was rated in four specific contaminant     water supply wells in Nassau County have suscepti-
categories for Long Island:                               bility ratings of medium-high or greater. Less than
                                                          25 percent of the public water supply wells have
· Microbials including protozoa, enteric bacteria
                                                          susceptibility ratings of low or medium. In Suffolk
   and enteric viruses.
                                                          County, almost 70 percent of the public drinking
· Nitrates                                                water supply wells have susceptibility ratings of
· Pesticides                                              medium-high or greater. More than 30 percent of
                                                          the wells were rated medium or low for VOCs.
· Volatile organic compounds (VOCs) including
   halogenated solvents, petroleum products and           Use of the results
   other industrial organic chemicals.
                                                          The source water assessments for Long Island build
A summary of the combined results for Nassau and          on an extensive history of state, regional and local
Suffolk Counties for each of the four categories of       resource management and protection programs. The
contaminants are presented below. Other potential         individual, site-specific well assessments provide
contaminants of concern such as chlorides, metals         resource managers with additional information for
and radionuclides also were addressed in individual,      establishing priorities to assure that the region's
site-specific public water supply well reports where      source waters are protected today and for future
these were identified as local water quality issues.      generations. Local water suppliers and county and
Microbials. More than 90 percent of the public            state health departments will use this information to
drinking water supply wells in Nassau County have         direct future source water protection activities.
a low susceptibility to microbial contamination. Only     These activities may include water quality monitor-
one percent of public water supply wells were rated       ing, resource management, planning and education
as medium-high or greater for microbials.                 programs.
About 60 percent of the public drinking water
                                                          For more information
supply wells in Suffolk County also have a low
susceptibility to contamination by microbials. Less       Visit us on the web:
than 20 percent of the public water supply wells          www.health.state.ny.us/nysdoh/water/swap.htm
were rated as medium-high or greater for microbi-         Or Contact:
als. Suffolk County's more shallow wells are more         Paul Kaczmarczyk or Ron Entringer
vulnerable to the presence of microbial sources in        New York State Department of Health
unsewered areas that have relatively short travel         (800) 458-1158 extension 2-7713; or
times from the water table to the well, particularly in   Your county health department representative:
central and eastern parts of the county.
                                                          Patricia Ramirez, Nassau County Department of
Nitrates. More than 80 percent of the public water        Health (516) 571-3323;
supply wells in Nassau County were rated as
                                                          Walter Dawydiak, Suffolk County Department of
medium-high or greater for nitrate susceptibility.
                                                          Health Services at (631) 853-3084.
More than 70 percent of the public water supply
wells in Suffolk County were rated with a medium-
high rating or greater for nitrates. Part of the reason
for the higher susceptibility is because nitrates
generally do not degrade rapidly in ground water.                                  New York State Department of Health
                                                                                Bureau of Public Water Supply Protection
Pesticides. No public water supply wells were rated                                   Flanigan Square, 547 River Street
with a high susceptibility to pesticides in Nassau                                                      Troy, NY 12180
County due to the relatively limited agricultural land