8. Water Resources and Hydrology
8.1 Water resource overview
The Central Pine Barrens encompasses regions of deep aquifer recharge,
as well as subsystems with shallow flow components that discharge to the
Peconic and Carmans Rivers. This complex hydrogeology controls the fate
of man-induced pollution, and therefore the quality of freshwater ecosystems.
Overall groundwater quality is still excellent in relation to drinking
water standards, particularly in the Magothy Aquifer. Limited degradation
of shallow groundwater quality has occurred, however, as reflected in the
elevated nitrogen concentrations of the Peconic and Carmans Rivers. These
rivers, and an unknown proportion of the Central Pine Barrens wetland systems,
are also impacted by stormwater runoff discharges, which may be the most
significant source of ecosystem-altering nutrients such as phosphorus.
These impacts can be expected to increase as additional areas are developed
unless densities, and activities that degrade groundwater and generate
contaminated stormwater, are controlled.
Measures designed to enhance and protect surface and groundwater resources
have previously been recommended in the Long Island Comprehensive
Waste Treatment Management Plan (the "208 Plan"; Long Island Regional
Planning Board, Hauppauge, NY, 1978), the Long Island Segment of
the Nationwide Urban Runoff Program (NURP; Long Island Regional
Planning Board, Hauppauge, NY, 1982), the Suffolk County Comprehensive
Water Resources Management Plan (WRMP; Suffolk County Department
of Health Services et. al., Hauppauge, NY, 1987), the Long Island
Comprehensive Special Groundwater Protection Area Plan (the SGPA
Plan; Long Island Regional Planning Board, Hauppauge, NY, 1993), and the
Tide Comprehensive Assessment and Management Program (BTCAMP; Suffolk
County Department of Health Services, Hauppauge, NY, 1992).
Many of these recommendations, particularly those related to drinking
water protection, have already been implemented through the Suffolk County
Sanitary Code and other regulations. However, other recommendations, including
those related to the control of stormwater runoff discharges and other
nonpoint sources of contamination, need additional institutional support.
The following hydrogeologically based recommendations for the Plan
highlight those previous recommendations that are considered most vital
to the particular ecological and water resource protection and enhancement
needs of the Central Pine Barrens, and suggest new approaches when necessary.
The recommendations include measures that should be implemented immediately,
as well as longer term efforts that may only be workable if additional
funding becomes available.
8.2 Immediate management recommendations
The actions which are appropriate for immediate implementation are
8.2.1 Mitigation of impacts of stormwater discharges to surface
To reduce nutrient, sediment, and pollutant loadings to surface waters,
structural and nonstructural mitigation measures should be designed and
implemented, where practical and feasible, for all existing and future
significant direct stormwater discharges to surface waters within the Central
Pine Barrens, i.e., where runoff is derived from major roads, golf courses,
agricultural fields, horse farms, etc.
8.2.2 Mitigation of shallow flow impacts upon the Peconic Estuary
To minimize the impacts of future development on water quality in the
Peconic River and Flanders Bay, BTCAMP recommendations for the shallow-flow
groundwater contributing area, including clustering, limits on new sewage
treatment plant surface water discharges, and the required use of Best
Management Practices related to lawn areas, fertilizer use and pesticide
applications should be implemented.
The Plan should provide for overall future development densities in
the Peconic River groundwatershed consistent with BTCAMP recommendations
by preserving extensive land areas and allowing increased densities in
other limited, designated receiving areas.
8.2.3 Sewage treatment
To further reduce existing and future impacts on surface and groundwater
quality within the Central Pine Barrens, all new and expanded sewage treatment
plants (STPs) should be required to utilize Best Available Technology for
nitrogen removal, with effluent discharge outside the Central Pine Barrens,
where technically and economically feasible. Adequate financial assurances
for proper long-term operation and maintenance should also be required.
In addition, an evaluation should be made of the cost-effectiveness
of sewering areas developed at densities exceeding Suffolk County Sanitary
Code Article 6 requirements to improve groundwater quality.
8.2.4 Suffolk County Sanitary Code adherence
To protect groundwater quality within the Compatible Growth Area from
potential pollution associated with future development, the relevant provisions
of Suffolk County Sanitary Code Articles 6, 7, and 12 should be strictly
applied, except as modified elsewhere in this document.
8.2.5 Transfer of development rights
To further reduce future impacts on surface and groundwater quality
within the Core Preservation Area, unsewered residential subdivisions based
on lots averaging as little as 20,000 square feet may be allowed within
the Compatible Growth Area where increased densities result from the transfer
of development rights from the Core Preservation Area, and the overall
number of dwelling units in the Core Preservation Area and Compatible Growth
Area combined will not be greater than that presently allowed under Suffolk
County Sanitary Code Article 6 requirements.
8.2.6 Clustering of residential development
To protect the water quality of existing public and private wells,
clustering of residential development on large parcels within the Compatible
Growth Area should be limited to building lots of no less than 20,000 square
feet where downgradient areas are served by private wells or where existing
public water supply wells may be significantly impacted.
8.2.7 Core Preservation Area wetlands water quality management
To protect and improve water quality, and maintain adequate water levels
within Core Preservation Area wetlands, the following actions are recommended:
1. Structural and non-structural mitigation measures should be designed
and implemented where practical and feasible for all existing direct stormwater
discharges to Core Preservation Area wetlands.
2. Surface drainage from future development should be prohibited from
being discharged directly to, or otherwise impacting, these systems.
3. New public water supply wells should be located at a sufficient
depth and distance from Core Preservation Area wetlands to avoid sustained,
permanent drawdowns at these wetlands which would significantly alter the
character of these wetlands.
8.2.8 Public supply and agricultural well screening guidance
To preserve the deeper portions of the aquifer system for future generations,
public water supply wells in the Central Pine Barrens should be screened
in the Upper Glacial or shallow Magothy Aquifers where distances to sensitive
surface water bodies and ambient water quality conditions (e.g., natural
iron content) allow. Similarly, agricultural wells should be kept as shallow
as possible to prevent the drawdown (i.e., accelerated vertical migration)
of nutrient and pesticide residues, and to recapture and recycle these
8.2.9 Establishment of a central hydrological data repository
To continue to provide the strongest possible technical basis for long-term
management decisions, ongoing hydrologic data collection efforts should
be expanded, and a central data repository should be established. Additional
information sources, such as the National Weather Service's NEXRAD radar
(Next Generation Radar; one installation is located at Brookhaven National
Laboratory) rainfall monitoring system, should be added to the database.
8.3 Intermediate term management recommendations
The following efforts should be commenced at Plan adoption and will
take a few years to provide useful management information:
8.3.1 Water level and chemical modeling of significant wetlands
To further refine our understanding of natural water level fluctuations
in Core Preservation Area wetlands, and the relative roles of groundwater
and runoff inputs, hydrologic studies that include water quantity and chemical
budgets should be conducted at significant wetland systems. Such studies
would be most appropriate for the least-impacted coastal plain ponds known
to be supporting rare and endangered species.
8.3.2 Fate of pollutant modeling and wetland restoration
To further refine our understanding of the fate of chemical pollutants
within Central Pine Barrens wetland systems, fine-scale wetland hydrologic
and water quality models should be developed. These models should then
be applied to impacted, but ecologically significant, wetland systems where
future restoration efforts will be made.
8.4 Long term management recommendations
The following efforts should be undertaken, as funding allows, to further
enhance the capability to manage the lands and resources to be preserved
and protected in the Central Pine Barrens:
8.4.1 Sensitivity analysis of Core Preservation Area wetlands
To refine our understanding of how controllable and uncontrollable
(e.g., rainfall) inputs to Core Preservation Area wetlands may affect efforts
to preserve and protect rare and endangered species, the sensitivity of
these specific aquatic flora and fauna to changes in physical and chemical
conditions should be determined. Emphasis should be placed on the biota
of those wetland systems that are presently least impacted.
8.4.2 Monitoring of water resource impacts of management programs
To provide a long-term evaluation of management programs related to
such activities as new agricultural crops (e.g., vineyards), fire management,
and camping, the impacts on water quality of these activities should be
monitored and evaluated on an on-going basis.
8.4.3 Delineation of the Carmans and Forge Rivers' contributing
To improve management programs for the Carmans and Forge Rivers, detailed
delineations of the shallow groundwater contributing areas of these systems
should be made.
8.4.4 Regional deep flow groundwater modeling
To better define deep flow through the aquifer system and the influence
such flow may have on coastal surface water bodies, regional groundwater
models should be refined and expanded.