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 Brown 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 the following:
8.2.1 Mitigation of impacts of stormwater discharges to surface waters
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 chemicals.
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 areas
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.