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Summary of Annual Hydrologic Conditions - 2003
Volume 3: Water-Quality
Yearly Trend of Precipitation, Stream Discharge, and Physical Water-Quality Characteristics Monitored at Several Index Stations
The drought New Jersey has been experiencing for more than four water years has diminished. The State received a total of 59.09 inches of precipitation during the 2003 water year (October 2002 to September 2003), making it the fifth wettest water year since 1896. This was quite a reversal from the third driest water year experienced in 2002. Precipitation was above the 1895-2002 mean for 8 months during the 2003 water year (fig. 1) (Statewide Monthly Precipitation 1895-2003, Climate Data, N.J. State Climatologist, Rutgers University; accessed at http://climate.rutgers.edu/stateclim/data/index.html). The monthly total for June (8.61 inches) was the highest for any June since 1896. During 4 additional months, surpluses greater than 1.5 inches occurred. January, April, May, and July had below average precipitation; however, no deficit greater than 0.65 inches occurred. Overall, precipitation was 14.35 inches (32 percent) above average during the 2003 water year. Streamflow was near or above normal throughout much of the year. Monthly mean discharge values for June and September set new maximum monthly mean values for the period of record at index stations Folsom and Trenton, respectively (fig. 2). All three index stations recorded above normal streamflow during the last one-third of the water year.
The precipitation and streamflow surpluses during water year 2003 and their diluting effects on solute concentrations are evident in the plot of monthly mean values of specific conductance (SC) at the continuous waterquality monitoring station on the Delaware River at Trenton (fig. 3). Monthly mean SC values, an indicator of solute concentrations, were below long-term (1968-2002) monthly mean values during 5 months. The correlation between streamflow and SC is less significant than that between precipitation and SC during winter months because even small precipitation events can carry salt used to deice roads, sidewalks, and parking lots into streams and result in higher solute concentrations. Therefore, when monthly mean SC values are expected to be low during high flow in winter months, the opposite is observed. During water year 2003, no long-term extremes for the period of record were exceeded.
Water year 2003 was the 29th coldest year since 1896 with an average ambient temperature of 51.5 oF (28.6 oC), 0.6 oF (0.3 oC) below the long-term (1968-2002) mean for the State (Statewide Monthly Precipitation 1895-2003, Climate Data). Monthly mean ambient temperatures during 8 months were at or below the long-term mean. Monthly mean water temperature values measured at the Delaware River at Trenton were below the long-term mean monthly values every month during water year 2003 (fig. 4). The monthly mean value for June established a new minimum for the period of record of 17.7 oC, 1.1 oC lower than the previous June minimum.
Dissolved oxygen (DO) concentrations generally exhibit an inverse relation to water temperature. As water temperature decreases, oxygen concentration increases; as water temperature increases, oxygen concentration decreases. DO, therefore, varies seasonally; yearly maximums occur in winter, and yearly minimums occur in summer. As expected, the highest monthly median of daily maximum DO concentrations, 16.0 milligrams per liter (mg/L), occurred in February when the monthly mean water temperature was at its lowest, 1.0 oC (fig. 5). The lowest monthly median of daily minimum DO concentrations, 7.4 mg/L, and the highest monthly mean water temperature, 24.6 o C, occurred in July. During water year 2003, no monthly medians of DO minimums and maximums exceeded long-term extremes for the period of record.
Ambient Stream Monitoring Network
The United States Geological Survey (USGS), in cooperation with the New Jersey Department of Environmental Protection (NJDEP), operates the cooperative Ambient Stream Monitoring Network (ASMN), which is designed to determine statewide water-quality status and trends, measure water quality near the downstream end of each NJDEP Watershed Management Area (WMA), define background water quality in each of the four physiographic provinces of New Jersey, and measure nonpoint source contributions from major land-use areas and atmospheric deposition. The ASMN consists of 116 stations located throughout the 20 WMAs. Four stations are located on the Delaware River main stem—the border between New Jersey and Pennsylvania—and are excluded from the following statistical plots of the ASMN data. The remaining 112 stations are segregated into 4 distinct types that together are used to define the surface-water quality in the State. Six background stations are located on reaches of streams that remain relatively unaffected by human activity, in order to develop a baseline water-quality database. Twenty-three Watershed Integrator (WI) stations are located near the farthest downstream point, not affected by tide, in one of the large drainage basins in each WMA, except 5, 9, and 16. The WI stations provide information on large drainange areas that integrate the effects of different types of land use and point and nonpoint contributions to surface-water quality within each WMA. Land Use Indicator (LUI) stations are used to monitor the effects of the dominant land use in each WMA and provide data on nonpoint source loading of contaminants to streams. Of the 43 LUI stations, 15 are designated undeveloped, 9 agriculture, 13 urban, and 6 mixed. Forty-two statewide status (SS) stations, at least two in each WMA, are chosen randomly to obtain a statistical basis that can be used to estimate values of water-quality indicators statewide. Individual tables of chemical constituents are located in the Surface-Water-Quality Station Records section of this report. In water year 2003, two of the SS stations were co-located at existing WI or LUI stations. Water-column samples were collected at each station to assess water-quality constituents that can be used as environmental indicators statewide. In addition to the regularly scheduled samples, a Watershed Reconnaissance study is devised annually according to specific project needs. The purpose of the Watershed Reconnaissance study in water year 2003 was to assess 3-day diurnal physical measurements and constituent concentrations at 12 network stations. This is discussed further in “Ambient Stream Monitoring Network Reconnaissance Study” in this summary.
Distribution of Selected Constituents in Filtered and Unfiltered Surface Water from Stations in the ASMN
Physical characteristics and concentrations of total and filtered nutrients, filtered common ions, filtered organic carbon, and biochemical oxygen demand were determined in samples from 112 stations in the ASMN. Samples were collected at each station four times a year during the periods November to December, February to March, May to June, and August to September. The analyzing laboratory used two different methods and reporting conventions for establishing the minimum concentration above which a quantitative measurement could be made. These reporting conventions were laboratory reporting level (LRL) and minimum reporting level (MRL). LRL was computed as twice the long-term method detection level (LT-MDL). Values reported less than the LRL or MRL were included in each distribution as a value equal to the LT-MDL or one-half the MRL, respectively. Values reported as “E”—estimated to be greater than the LT-MDL but less than the LRL—were included in the plots. Refer to the Definition of Terms section of this report for further explanation of these reporting conventions.
The plots in figure 6 (6a) illustrate the relation between land use and water quality. Streams that drain urban and agricultural areas seem to be negatively affected by wastewater discharges and overland runoff, respectively. In contrast, streams that drain background areas have the highest DO concentrations and streams that drain background and undeveloepd areas have the lowest concentrations of most other constituents, except DOC. The lowest median DO concentration, 74 percent of saturation; the highest median total dissolved solids (TDS) concentration, 234 mg/L; the highest median ammonia concentration, 0.10 mg/L; and the highest median chlorophyll a concentration, 0.5 ìg/L, occurred at urban LUI stations. In contrast, the highest median DO concentration, 95.8 percent of saturation; the lowest median TDS concentration, 61 mg/L; the lowest median ammonia concentration, 0.015 mg/L; and the lowest median chlorophyll a concentration, 0.5 ìg/L, occurred at background stations. The highest median BOD concentration, 1.3 mg/L; the highest median turbidity, 8.1 NTU; and the highest median nitrite plus nitrate concentration, 1.49 mg/L, occurred at agriculture LUI stations. In contrast, the lowest median BOD concentration, 0.50 mg/L, and the lowest nitrite plus nitrate concentration, 0.065 mg/L, occurred at undeveloped stations; the lowest turbidity, 0.75 NTU, occurred at background stations. Dissolved organic carbon (DOC) is a heterogeneous mixture of many organic materials, mostly high molecular weight organic acids that result from the oxidation of organic matter. Organic matter can originate from anthropogenic or natural sources. Streams in urban areas have been found to have high levels of organic carbon caused by nutrient enrichment. Streams in undeveloped areas have been found to have high levels caused by naturally occurring organic matter. The highest median concentration of DOC, 9.2 mg/L, occurred at undeveloped stations; the lowest median concentration occurred at agriculture LUI stations.
Distribution, Detection Frequency, and Concentration of Recoverable Trace Elements in Whole Water and Bed Sediment, Nutrients and Organic Compounds in Bed Sediment, Volatile Organic Compounds in Whole Water, and Pesticides in Filtered Samples from Selected Stations in the ASMN
Water samples for analysis of trace elements, volatile organic compounds (VOCs), and pesticides were collected during the period when the constituents were most likely to have been detected, during August and September, February and March, and May and June, respectively. Samples of bed sediment were collected in low-water conditions during August and September. For ease of discussion, only those constituents detected in one or more samples are shown in the figures or tables on pages 12 through 16. A detected constituent is one whose value is reported to be greater than or equal to the laboratory LRL or MRL. Values reported by the analyzing laboratory as “<”—less than the LRL or MRL—were considered to be not detected and were excluded from the plots. Values reported as “E”—estimated below the LRL or MRL—were included in the plots. Refer to the Definition of Terms section of this report for more information about MRLs and LRLs.
Samples for the analysis of whole-water-recoverable trace elements were collected at 6 background stations to develop a baseline with which to compare the water quality at other stations and at 42 SS stations to provide a general overview of water quality statewide and of the aerial distribution of these compounds. All 15 trace elements analyzed in samples at the USGS National Water Quality Laboratory were detected in one or more samples and, therefore, were included in figure 7. Barium, boron, iron, lead, manganese, and nickel were detected in 100 percent of the samples, and copper, selenium, and zinc were detected in all but one of the samples. Chromium, mercury, and silver had the lowest percentages of detection, 33, 27, and 2, respectively. Arsenic, chromium, mercury, and silver were not detected at any background station. In general, median concentrations were smaller in samples from background stations, which are located on reaches of streams that remain relatively unaffected by human activity.
Bed-sediment samples for the analysis of nutrients, trace elements, polycyclic aromatic hydrocarbons (PAHs), and total polychlorinated biphenyls (PCBs) were collected at 2 background and 20 SS stations. Two of the six background stations are sampled for bed sediment each year and are resampled every third year. In water year 2003, 20 of the 46 SS stations were selected for sampling on the basis of the availability of bed sediment. Ammonia plus organic nitrogen, phosphorus, and total carbon were detected in all samples (fig. 8). Selenium was the only element in the laboratory schedule not detected in any sample. Cadmium, cobalt, iron, lead, and nickel were detected in 100 percent of the samples (fig. 9). Arsenic and mercury had the lowest percentages of detection, 23 and 9, respectively. Mercury, the only element not detected at either of the background stations, was detected at only two of the SS stations. Of the 30 PAHs and PCBs in the laboratory schedule, only those compounds with surface-water-quality standards are presented in the figure and table. Pyrene was the most frequently detected compound at 91 percent of the stations (fig. 10). Dibenz(a,h)anthracene was the least detected compound at 45 percent of the stations. Four compounds were not detected at either of the background stations, and seven compounds were detected at only one of the background stations. PCBs were detected at estimated concentrations at nine of the SS stations and at none of the background stations (table 1).
Samples from 6 background and 42 SS stations were analyzed for 34 VOCs. Seven compounds were detected in more than one sample (fig. 11), and four compounds were detected only once (table 2). The most frequently detected VOCs in 48 samples were methyl tertiary butyl ether (MTBE), in 54 percent of samples; chloroform, in 21 percent; and tetrachloroethylene, in 17 percent. Chloroform and toluene were the only two compounds detected in samples from background stations.
Filtered samples from 6 background and 42 SS stations were analyzed for 52 pesticides by use of laboratory schedule 2001. Only compounds detected in one or more samples are included in figure 12 and tables 3 and 4. Refer to “Laboratory Measurements” in the Explanation of Water-Quality Records section of this report for the complete list of compounds and the LRL for each compound. Twenty-four pesticides were detected in low concentrations and were widely distributed throughout the State. All 24 compounds were detected at one or more SS stations, but only five compounds were detected at background stations. Seven of the detected compounds were insecticides— Azinphos-methyl, Carbaryl, Carbofuran, Diazinon, Dieldrin, Malathion, and cis-Permathrin. The remaining compounds were herbicides. The most frequently detected pesticides in 48 samples were Metolachlor, in 67 percent of samples; Atrazine, in 65 percent; and Prometon, in 58 percent. The five compounds detected at background stations are commonly used herbicides.
Ambient Stream Monitoring Network Reconnaissance Study
The water year 2003 reconnaissance study continuously monitored water temperature, DO concentration, DO percent of saturation, specific conductance, and pH at 12 network stations during summer baseflow conditions. Insitu multi-constituent sensors, or monitors, recorded the occurrence and magnitude of diurnal variations that could not be observed when instantaneous samples were collected during quarterly station visits. Instantaneous values generally were collected between the hours of 8 a.m. and 2 p.m. The monitors were deployed for a 3-day period at each station during July, August, or September. Statistical summaries for the periods of record for all stations are shown in figure 13; graphs of hourly values for each of the stations are included in the Surface-Water-Quality Station Records section of this report (figs. 25-26, 32-39, and 43-44).
Reconnaissance stations were selected on the basis of previous occurrences of DO supersaturation (greater than 120 percent of saturation) or DO undersaturation (less than 60 percent of saturation). Three stations—01398000, 0140500, and 01403300— recorded maximum dissolved oxygen above 120 percent of saturation—201, 150, and 130, respectively. Three stations—01367770, 01398000, and 01443250—recorded minimum values below 60 percent of saturation—47, 53, and 10, respectively. The greatest diurnal variance of water temperature, dissolved oxygen, and pH occurred at stations 01398000 and 01400500.
Ambient Ground-Water-Quality Network
The USGS, in cooperation with the NJDEP, operates the cooperative Ambient Ground-Water-Quality Network (AGWQN), which is designed to assess the status of ground-water quality by examining the concentrations of various constituents that can be used as environmental indicators, assess long-term water-quality trends, determine the effects of land use on shallow ground-water quality, identify threats from nonpoint sources of contamination, and identify emerging or new environmental issues of concern to the public. The network consists of 150 shallow ground-water wells distributed throughout New Jersey within three land-use types. Sixty wells are located in agricultural areas, 60 in urban/suburban areas, and 30 in undeveloped areas within New Jersey’s five watershed management regions (WMRs)–the Passaic, the Raritan, the Upper Delaware, the Lower Delaware, and the Atlantic Coastal. These five WMRs are further divided into 20 watershed-management areas (WMAs).
Thirty-five shallow wells were sampled in water year 2003. Four wells are located in the Passaic WMR in WMAs 3 and 6. Twenty-one are located in the Raritan WMR in WMAs 7-10. Nine are located in the Upper Delaware WMR in WMAs 1 and 11. One is located in the Lower Delaware WMR in WMA 20. The wells have 2-inch polyvinylchloride casings; range in depth from 17 to 208 feet; and represent 3 land-use types, 6 water-chemistry types, and 10 hydrogeologic units (table 5). Samples from the wells were analyzed for physical characteristics, major ions, nutrients, trace elements, organic constituents, and gross alpha and beta radioactivity. A summary of the water chemistry of the 35 wells is listed in table 5. Individual tables of chemical constituents are located in the Ground-Water-Quality Site Records section of this report.
Distribution, Detection Frequency, and Concentration of Selected Constituents in Filtered Samples from 35 Sites in the AGWQN
Field measurements were made of physical and chemical characteristics of water samples from 35 wells in the AGWQN. Analyses then were conducted to determine concentrations of major ions, filtered nutrients, organic carbon, trace elements, VOCs, and pesticides. The effect of land use on the proportions of the major ions in water samples from the wells can be observed in the data presented in the trilinear (Piper) diagrams (figs. 14, 15, 16). The diagrams depict major cations (calcium, sodium, magnesium, potassium) and anions (bicarbonate, chloride, sulfate, fluoride, nitrate) as percentages of milliequivalents in the two base triangles. The total cations and anions in milliequivalents are set to equal 100 percent. The individual points then are projected to the quadrilateral along parallel lines following the magnesium and sulfate axes. The relative proportions of major ions in an individual sample can be inferred by the position of the well symbol in the diagram. Similarity or dissimilarity between samples can be inferred from the clustering or scattering of symbols in the diagram.
Concentrations and frequencies of detection are summarized in scatter plots and tables on pages 23-25. Values reported by the analyzing laboratory as “<“—less than the LRL—were considered to be not detected and were excluded from the plots. Values reported as “E”—estimated below the LRL—were included in the plots. Refer to the Definition of Terms section of this report for further explanation of these reporting conventions. Samples from wells in undeveloped areas have the lowest median concentrations of hardness, TDS, nitrite plus nitrate, barium, and boron and the highest median concentrations of DOC and zinc (figs. 17-18). Samples from wells in urban areas have the highest median concentrations of boron, cadmium, chromium, iron, nickel, and selenium. Samples from wells in agriculture areas have the highest median concentrations of nitrite plus nitrate, and aluminum. Barium, boron, copper, manganese, nickel, and zinc were detected in 100 percent of the samples. Mercury and antimony were the least frequently detected trace elements, 3 and 6 percent, respectively, and both were detected only in samples from wells in urban areas.
Concentration and Detection Frequency of Selected Organic Constituents in Filtered Samples from 35 Sites in the AGWQN
Samples from 35 wells were analyzed for 34 VOCs. Only those detected in one or more samples are listed in table 6. Samples from wells in urban areas had the most detections; samples from undeveloped areas had the fewest. The most frequently detected VOCs in samples from wells located in all land-use areas were Methyl tert-butyl ether, 26 percent; trichloromethane, 14; and trichloroethene, 9.
Filtered samples from 35 wells were analyzed for 52 pesticides by use of USGS National Water Quality