Michael E. Serfes, Hydrogeologist

New Jersey Geological Survey

New Jersey is a hydrogeologically diverse, densely populated and highly industrialized state. Successful management of the State’s ground-water and surface-water resources requires an effective monitoring program. The Ambient Ground Water Quality Network : a cooperative New Jersey Geological Survey and United States Geological Survey project, was started in 1982. Since that time 364 regional network wells, currently 22 wells yearly, have been sampled for: field parameters, major ions, nutrients, trace elements, radioactivity, and volatile organic compounds. Goals for the network (established in 1986) are to: 1. Determine the chemical concentration ranges of ground-water constituents within and between rock types, 2. Determine the geochemical reasons for any differences, and 3. Determine long term trends in ambient quality by resampling using an 8- to 20- year cycle.

The first two goals were accomplished by 1995 mainly by sampling wells unaffected by known point sources. During 1996 and 1997, a pilot watershed network design guided sampling to address the third goal. In 1997, it was decided to redesign New Jersey’s surface and ground-water quality networks to address current information needs.

Goals of the new ground-water network are: 1. To assess the water-quality status, 2. To assess water-quality trends, 3. To evaluate transfer relations, 4. To identify emerging issues. To accommodate these goals the network will consist of 150 water-table wells, located using a stratified-random site selection approach. Statewide distribution of the 150 wells will be: 60 in agricultural areas, 60 in urban/suburban areas, and 30 in undeveloped land use areas.

New Jersey is the fifth smallest state in the nation yet is one of the most hydrogeologically diverse (figure 1). Approximately 8 million people live within New Jersey’s 7,836 square miles making it the most densely populated state in the nation. Highly concentrated urban and industrial centers, shrinking agricultural and undeveloped areas, expanding suburban areas and protected and unprotected undeveloped areas generally characterize the State’s land use (figure 2). Because of the high population and variable land uses, the State’s streams, lakes, ponds, bays, ocean and ground water are impacted to varying degrees by point and non-point sources of pollution. To understand and properly manage the quality of water in the state it is necessary to establish effective monitoring programs. One such program is New Jersey’s Ambient Ground Water Quality Network (AGWQN).

New Jersey’s AGWQN is a cooperative program between the New Jersey Department of Environmental Protection (NJDEP) and United States Geological Survey (USGS) and is funded under section 106 of the Federal Clean Water Act, the NJDEP and a USGS fund match. It is part of the NJDEP/USGS cooperative Water Quality Surveillance Network that originally only involved monitoring surface-water quality and ground-water levels. The ground-water quality network was started in 1982 in response to the growing need for adequate ambient ground-water-quality data by regulators. From 1982 to 1997, 364 regional network wells have been sampled (Figure 3). A list of the current physical and chemical parameters analyzed are given in table 1. These include:

1. Field parameters
2. Major ions
3. Nutrients
4. Trace elements
5. Radioactivity
6. Volatile Organic Compounds

The field sampling and analytical procedures and protocols follow the QA/QC guidelines used by the USGS.

During the first few years an intensive ground-water-quality assessment was conducted in the Ramapo and Rockaway glacial valleys in northern New Jersey at the same time regional sampling was conducted in the Coastal Plain of southern New Jersey. In 1986 a lack of data in the northern bedrock portion of the state was acknowledged and became the focus of subsequent sampling. Finalized goals for the network were also established during that time. Those goals were to determine:

1. The chemical ranges of ground-water constituents within and between rock types.
2. The geochemical reasons for the differences observed
3. Long term trends in ambient quality by resampling using an 8 to 20 year cycle.

From 1987 to 1995, 210 wells were sampled in northern New Jersey. Of those, 165 were in fractured bedrock and 45 were in glacial and other unconsolidated surficial materials (Serfes, 1994 & 1998). Data from the bedrock portion of the Newark Basin can be found at http://www.state.nj.us.dep.njgs.

In meeting the first two goals above, wells were selected so that they would not be influenced by known point sources of pollution. Wells down gradient from pollution sites were avoided. Thus the sampling is biased toward natural ground-water quality. Determining the exact recharge area for deep wells in fractured bedrock and stratified glacial deposits is very complex and beyond the scope of the network. Therefore, non-point source pollution from various land uses was not considered in the well selection process. Some samples did however contain nitrate concentrations above background (<1mg/L) indicating land use impacts.

In 1996 a network design was devised to complement the NJDEP watershed process and address the third goal above. The main objective was to determine how up-gradient land use affects the quality of ground water discharging to streams throughout the state. Wells were to be sampled on a periodic basis so that trends could be evaluated. During 1996 and 1997, 44 shallow wells near streams were sampled in the Barnegat Bay and Rancocas Creek watersheds. In 1997 the NJDEP and USGS decided to review and redesign the surface and ground-water quality networks to address current information needs and take us into the 21st century. The results of the ground-water network redesign are given below.

A committee consisting of NJDEP and USGS staff have established the goals and a preliminary redesign of the network. The goals of the network are:

1. To assess the ground-water quality status.
2. To assess the ground-water quality trends.
3. To evaluate transfer relations (ex: correlate water quality to land use).
4. To identify emerging issues (ex: mercury in ground water).

The committee also agreed on several objectives. These are:

1. To evaluate land use impacts to ground water.
2. To accommodate watershed assessments at the Watershed Management Region level.
3. To fulfill a National Performance Partnership System (NEPPS) commitment to evaluate ambient ground-water quality at the water table in New Jersey.

New Jersey’s watershed management areas and regions are shown in figure 3. The proposed network addresses the new network goals and objectives, and is designated the Ambient Water Table Quality Monitoring Network.

The quality of ground water at the water table is generally the first and most significantly impacted portion of the ground-water system. Because the hydraulic connection with the land surface is generally vertical, land use activities should directly correlate with ground-water quality at the wells. Determining the exact recharge areas and time of travel for deeper wells is generally much more difficult.

The proposed Ambient Water Table Quality Monitoring Network consists of 150 water-table wells randomly distributed throughout the state within 3 broad land use stratification’s (figure 4). The stratified-random site selection process was conducted using a method outlined in Scott (1990). The 150 wells will be in agricultural lands (60), urban/suburban lands (60) and undeveloped lands (30). This network will also serve as an early warning system for identifying emerging threats to ground water quality.

Preliminary work by the USGS has shown that a random statewide site selection process based on 1986 land use, yields an approximately equal area weighting of sites for the 3 land uses within each of the State’s 5 Watershed Management Regions (figure 4).

Shallow wells will be installed unless suitable ones exist at the random sites selected. Approximately 30 shallow wells will be sampled each year in one of the five Watershed Management Regions. Therefore, the network will be completely sampled every 5 years.

The current list of physical and chemical parameters analyzed for the network samples will be reviewed and revised as appropriate. Also, the field criteria for siting wells, such as the acceptable percent of the target land use, site access concerns, and monitor well construction, need to be determined.

The status of the water-table ground-water quality in New Jersey will be determined using various indicators (for example, nitrate concentration). Nonparametric statistical measures such as the median and other percentiles, will be determined using the indicator concentration data. Confidence intervals for these percentile values will be determined using the method outlined in Spruill and Candela (1990).

One of the 5 Watershed Management Regions will be sampled each year. Therefore, the entire network, and individual WMRs, will be sampled on a 5 year cycle. After at least two cycles, water quality trends can start to be developed.

The ability to determine a cause and effect for water-quality concerns is very important. By sampling wells screened just below the water table, a direct hydraulic connection to the overlying land surface can usually be made. Activities at the land surface can be assessed for causal effects.

The quality of ground water at the water table is generally the first and most significantly impacted portion of the ground-water system. New threats to ground-water quality from non point sources of pollution should be detectable there first. It is also a good place to start looking for compounds that are newly identified or are of recent concern in the environment. Examples are the controversial endocrine disrupting compounds and MTBE.

Appreciation is extended to the USEPA for funding, and all persons from the NJDEP and USGS that were involved in establishing and maintaining, the Ambient Ground Water Quality Network. Special thanks go to those from NJDEP and USGS currently involved in the redesign process, particularly USGS staff: Mark Ayers and Eric Vowinkel for their technical advice and Paul Stackelberg for that and producing the stratified random well-site maps .

Field Alkalinity (mg/L as CaCO₃) Solids, dissolved (mg/L)Hardness,(mg/L as CaCO₃) Specific Conductance (uS/cm)Oxygen, dissolved (mg/L) TemperaturepH (standard units) Major and Minor

Dissolved Constituents (mg/L)

Calcium Potassium

Chloride Silica Fluoride SodiumMagnesium SulfateNutrients, Dissolved (mg/L)

Nitrogen, NH₃, (as N) Nitrogen, NO₂, (as N)

Nitrogen, NH₃ + Organic, (as N) Nitrogen, NO₂+NO₃, (as N)

Nitrate, [NO₂+NO₃] - [NO₂] Phosphorous ortho, (as P)

Aluminum LeadArsenic ManganeseBarium MercuryCadmium Selenium Chromium SilverCopper ZincIron Organic ConstituentsDOC- Dissolved Organic Carbon, (mg/L as C)

VOC- Volatile Organic Compounds