Groundwater quality may be affected by natural and human factors (Johnston, 1988). Although the vulnerability of groundwater to contamination from the land surface is influenced by many factors, the degree of aquifer confinement, the depth of the well, and the surrounding land use are primary key factors that influence shallow groundwater quality.
Unconfined aquifers generally are much more vulnerable to contamination than confined aquifers. For a well in a confined aquifer, the farther the well is from the unconfined area, the less vulnerable it is to contamination. Generally, the deeper the well, the less vulnerable it is to contamination. Finally, because human activities greatly affect the quality of water that recharges an aquifer, the amount and type of land use in the area that contributes water to the well is a key factor in determining aquifer vulnerability to contamination (Clawges and others, 1999).
Two of the factors that have the greatest effect on groundwater quality are the land-use practices in the recharge area above the aquifer(s) and the groundwater-flow patterns within the aquifer(s) (Haefner, 1992).
Groundwater quality data on Long Island has been collected for many years by the USGS and other Federal, State and local agencies. A recent map of contamination sites that have the potential to impact groundwater across Long Island is shown in Figure 28. This map was created by the U.S. Environmental Protection Agency, using information maintained by the New York State Department of Environmental Conservation.
Water Quality Data
The USGS collects and analyzes chemical, physical, and biological properties of water, sediment and tissue samples from across the Nation. The Water Data for the Nation discrete sample database is a compilation of over 4.4 million historical water quality analyses in the USGS district databases through September 2005. The discrete sample data is a large and complex set of data that has been collected by a variety of projects ranging from national programs to studies in small watersheds.
At selected surface-water and groundwater sites, the USGS maintains instruments that continuously record physical and chemical characteristics of the water including pH, specific conductance, temperature, dissolved oxygen, and percent dissolved-oxygen saturation. Supporting data such as air temperature and barometric pressure are also available at some sites. At sites where this information is transmitted automatically, data are available from the current data system.
There are over 4,200 sites on Long Island that had a water quality sample measurement taken since the early 1900's. The largest sample collections occurred between 1970-1990, where over 2,100 sites were sampled. Currently, for the period 2010-2014, only 117 sites have a water quality sample. Real time water quality data map service is available for several field parameters like water temperature.
- Groundwater
Groundwater will normally look clear because the ground naturally filters out particulate matter. However, both natural and anthropogenic compounds can be found in groundwater. As groundwater flows through the ground, metals such as iron and manganese are dissolved and may later be found in high concentrations in the water. Industrial discharges, urban activities, agriculture, groundwater pumpage, and disposal of waste all can affect groundwater quality.
Contaminants can be human-induced, as from leaking fuel tanks or toxic chemical spills. Pesticides and fertilizers applied to lawns and crops can accumulate and migrate to the water table. Leakage from septic tanks and/or waste-disposal sites also can introduce bacteria to the water, and pesticides and fertilizers that seep into farmland can eventually end up in water drawn from a well. In some instances, a well might have been drilled in proximity to land that was once used for a landfill or chemical dump site. In any case, if you use your own well to supply drinking water to your home, it is wise to have your well water tested for chemicals and contaminates.
- Surface Water
As watersheds are urbanized, much of the vegetation is replaced by impervious surfaces, thus reducing the area where infiltration to groundwater can occur. Thus, more stormwater runoff occurs — runoff that must be collected by extensive drainage systems that combine curbs, storm sewers, and ditches to carry stormwater runoff directly to streams. More simply, in a developed watershed, much more water arrives into a stream much more quickly, resulting in an increased likelihood of more frequent and more severe flooding.
As it flows over the land surface, stormwater picks up potential pollutants that may include sediment, nutrients (from lawn fertilizers), bacteria (from animal and human waste), pesticides (from lawn and garden chemicals), metals (from rooftops and roadways), and petroleum by-products (from leaking vehicles). Pollution originating over a large land area without a single point of origin and generally carried by stormwater is considered non-point source pollution.
_______________________________
Table of Contents
State of the Aquifer, Long Island, New York - Introduction
- Precipitation
- NWIS - the USGS Data Archive
- Surface Water - Streamflow
- Groundwater Levels
- Water Table and Surface Maps
- Water Use
- Groundwater Budget
- Inflow to the Groundwater System
- Outflow from the Groundwater System
Below are other science projects associated with this project.
Long Island Water Availability
Long Island Precipitation
NWIS - the USGS Data Archive
Long Island Surface Water - Streamflow
Long Island Groundwater Levels
Long Island Water Table and Surface Maps
Long Island Water Use
Long Island Groundwater Budget
Long Island Inflow to the Groundwater System
Long Island Outflow from the Groundwater System
Long Island Water Suitability Case Studies
Long Island Groundwater System Potential Hazards
- Overview
Groundwater quality may be affected by natural and human factors (Johnston, 1988). Although the vulnerability of groundwater to contamination from the land surface is influenced by many factors, the degree of aquifer confinement, the depth of the well, and the surrounding land use are primary key factors that influence shallow groundwater quality.
Unconfined aquifers generally are much more vulnerable to contamination than confined aquifers. For a well in a confined aquifer, the farther the well is from the unconfined area, the less vulnerable it is to contamination. Generally, the deeper the well, the less vulnerable it is to contamination. Finally, because human activities greatly affect the quality of water that recharges an aquifer, the amount and type of land use in the area that contributes water to the well is a key factor in determining aquifer vulnerability to contamination (Clawges and others, 1999).
Two of the factors that have the greatest effect on groundwater quality are the land-use practices in the recharge area above the aquifer(s) and the groundwater-flow patterns within the aquifer(s) (Haefner, 1992).
Figure 28. Generalized locations of contamination sites that have the potential to impact groundwater quality, in Nassau and Suffolk Counties, N.Y.(Source: U.S. Environmental Protection Agency).(Public domain.) Groundwater quality data on Long Island has been collected for many years by the USGS and other Federal, State and local agencies. A recent map of contamination sites that have the potential to impact groundwater across Long Island is shown in Figure 28. This map was created by the U.S. Environmental Protection Agency, using information maintained by the New York State Department of Environmental Conservation.
Water Quality Data
The USGS collects and analyzes chemical, physical, and biological properties of water, sediment and tissue samples from across the Nation. The Water Data for the Nation discrete sample database is a compilation of over 4.4 million historical water quality analyses in the USGS district databases through September 2005. The discrete sample data is a large and complex set of data that has been collected by a variety of projects ranging from national programs to studies in small watersheds.
At selected surface-water and groundwater sites, the USGS maintains instruments that continuously record physical and chemical characteristics of the water including pH, specific conductance, temperature, dissolved oxygen, and percent dissolved-oxygen saturation. Supporting data such as air temperature and barometric pressure are also available at some sites. At sites where this information is transmitted automatically, data are available from the current data system.
There are over 4,200 sites on Long Island that had a water quality sample measurement taken since the early 1900's. The largest sample collections occurred between 1970-1990, where over 2,100 sites were sampled. Currently, for the period 2010-2014, only 117 sites have a water quality sample. Real time water quality data map service is available for several field parameters like water temperature.
- Groundwater
Groundwater will normally look clear because the ground naturally filters out particulate matter. However, both natural and anthropogenic compounds can be found in groundwater. As groundwater flows through the ground, metals such as iron and manganese are dissolved and may later be found in high concentrations in the water. Industrial discharges, urban activities, agriculture, groundwater pumpage, and disposal of waste all can affect groundwater quality.
Contaminants can be human-induced, as from leaking fuel tanks or toxic chemical spills. Pesticides and fertilizers applied to lawns and crops can accumulate and migrate to the water table. Leakage from septic tanks and/or waste-disposal sites also can introduce bacteria to the water, and pesticides and fertilizers that seep into farmland can eventually end up in water drawn from a well. In some instances, a well might have been drilled in proximity to land that was once used for a landfill or chemical dump site. In any case, if you use your own well to supply drinking water to your home, it is wise to have your well water tested for chemicals and contaminates.
- Surface Water
As watersheds are urbanized, much of the vegetation is replaced by impervious surfaces, thus reducing the area where infiltration to groundwater can occur. Thus, more stormwater runoff occurs — runoff that must be collected by extensive drainage systems that combine curbs, storm sewers, and ditches to carry stormwater runoff directly to streams. More simply, in a developed watershed, much more water arrives into a stream much more quickly, resulting in an increased likelihood of more frequent and more severe flooding.
As it flows over the land surface, stormwater picks up potential pollutants that may include sediment, nutrients (from lawn fertilizers), bacteria (from animal and human waste), pesticides (from lawn and garden chemicals), metals (from rooftops and roadways), and petroleum by-products (from leaking vehicles). Pollution originating over a large land area without a single point of origin and generally carried by stormwater is considered non-point source pollution.
_______________________________
Table of Contents
State of the Aquifer, Long Island, New York - Introduction
- Precipitation
- NWIS - the USGS Data Archive
- Surface Water - Streamflow
- Groundwater Levels
- Water Table and Surface Maps
- Water Use
- Groundwater Budget
- Inflow to the Groundwater System
- Outflow from the Groundwater System
- Science
Below are other science projects associated with this project.
Long Island Water Availability
The foundation of any groundwater analysis, including those analyses whose objective is to propose and evaluate alternative management strategies, is the availability of high-quality data. Some, such as precipitation data, are generally available and relatively easy to obtain at the time of a hydrologic analysis. Other data and information, such as geologic and hydrogeologic maps, can require...Long Island Precipitation
The National Oceanic and Atmospheric Administration (NOAA) National Climatic Data Center (NCDC) offers several types of climate information generated from examination of the data in the archives. These types of information include record temperatures, record precipitation and snowfall, climate extreme statistics, and other derived climate products. A collection of statistical weather and climate...NWIS - the USGS Data Archive
As part of the U.S. Geological Survey's (USGS) program for disseminating water data within USGS, to USGS cooperators, and to the general public, the USGS maintains a distributed network of computers and fileservers for the acquisition, processing, review, and long-term storage of water data. This water data is collected at over 1.5 million sites around the country and at some border and...Long Island Surface Water - Streamflow
Surface water current conditions are based on the most recent data from on-site automated recording equipment. Measurements are commonly recorded at a fixed interval of 15 to 60 minutes and transmitted by satallite uplink or telephone telemetry to the USGS every hour. Values may include "Approved" (quality-assured data that may be published) and/or more recent "Provisional" data (of unverified...Long Island Groundwater Levels
Water-level measurements from observation wells are the principal source of information about the hydrologic stresses acting on aquifers and how these stresses affect groundwater recharge, storage, and discharge (Taylor and Alley, 2001). Water-level measurements are made by many Federal, State, and local agencies.Long Island Water Table and Surface Maps
The depth to the water table can be determined by installing wells that penetrate the top of the saturated zone just far enough to respond to water table fluctuations. Preparation of a water-table map requires that only wells that have their well screens installed near the water table be used. If the depth to water is measured at a number of such wells throughout an area of study, and if those...Long Island Water Use
The U.S. Geological Survey's National Water-Use Information Program (NWUIP) is responsible for compiling and disseminating the nation's water-use data. The USGS works in cooperation with local, State, and Federal environmental agencies to collect water-use information. USGS compiles these data to produce water-use information aggregated at the county, state, and national levels. Every five years...Long Island Groundwater Budget
A groundwater system consists of a mass of water flowing through the pores or cracks below the Earth's surface. This mass of water is in constant motion. Water is constantly added to the system by recharge from precipitation, and water is constantly leaving the system as discharge to surface water and as evapotranspiration. Each groundwater system is unique in that the source and amount of water...Long Island Inflow to the Groundwater System
Precipitation that infiltrates and percolates to the water table is Long Island's only natural source of freshwater because the groundwater system is bounded on the bottom by relatively impermeable bedrock and on the sides by saline ground water or saline bays and the ocean. About one-half the precipitation becomes recharge to the groundwater system; the rest flows as surface runoff to streams or...Long Island Outflow from the Groundwater System
The flow of water leaving, or discharging, the groundwater system of Long Island occurs naturally through streams, as base flow, at the coastline as shoreline discharge and sub-sea discharge, and through pumping wells as withdrawals. Estimates of each component of outflow from the groundwater system is presented and summarized in this section using streamflow measurements, and a compilation of...Long Island Water Suitability Case Studies
A collection of studies that focused on the quality of groundwater and surface water, are presented in this section. The reports associated with these areas of water quality concerns are linked as an online source for further reading.Long Island Groundwater System Potential Hazards
Hazards which may impact the ground water system adversely are presented in this web page. The impacts of these hazards are only shown here as a topic for further discussion and may need to be investigated with further details.