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Summary of Annual Hydrologic Conditions - 2002

Volume 3: Water-Quality

Surface Water Quality Yearly Trend of Precipitation, Stream Discharge, and Physical Water-Quality Characteristics Monitored at Several Index Stations

New Jersey has been experiencing ongoing drought conditions for more than four years. The 2002
water year (October 2001 to September 2002) with a total of 33.99 inches of precipitation was the third driest water year since 1896. Precipitation was below average for 7 months during the 2002 water year (fig. 1) (Statewide Monthly Precipitation 1895-2002, Climate Data, N.J. State Climatologist, Rutgers University; accessed at http://climate.rutgers.edu/stateclim/ data/index.html). During four of the seven months, deficits of precipitation greater than 2.3 inches occurred, and during two months, deficits greater than 1.2 inches occurred. March, April, May, June, and September had above average precipitation; June had the greatest surplus,1.2 inches. September 2001 to February 2002 was the driest consecutive 6 months of any 6-month interval on record (Statewide Monthly Precipitation 1895-2002, Climate Data). Overall, precipitation was 10.73 inches (76 percent) below normal during the 2002 water year. Streamflow was below normal throughout much of the year. Monthly mean discharge values for November, February, and March set new minimum monthly mean values for the period of record at index stations High Bridge and Folsom (fig.2). Trenton was the only index station that recorded above normal streamflow at any time during the water year; it occurred during the months of May and June.

Figure 1. Monthly mean precipitation for water year 2002 and mean-monthly precipitation for 1895-2001.

Figure 2. Monthly mean discharge at index gaging stations, water year 2002.

Figure 1 Figure 2

The substantial yearlong precipitation and streamflow deficits, and their resultant effects on solute concentrations, are evident in the plot of monthly mean values of specific conductance (SC) at the continuous water-quality monitoring station on the Delaware River at Trenton (fig. 3). Ten of the 12 monthly mean values of SC for the 2002 water year were above long-term (1968-2001) mean-monthly values. During May and June, the months of above normal statewide precipitation and streamflow at Trenton, monthly mean SC values were below the long-term mean-monthly values. During November and January, two of the months with the lowest mean discharge values for the water year, SC values exceeded the highest monthly mean values for the period of record.

Water year 2002 was the warmest water year on record with an average ambient temperature of 55.9oF (13.3oC), 3.8oF (2.1oC) above normal for the State. The long-term (1895-2001) mean-monthly ambient temperature values were exceeded every month, except May (Statewide Monthly Precipitation 1895-2002, Climate Data). Monthly mean water temperature values measured at the Delaware River at Trenton followed a similar trend. Long-term mean-monthly values were exceeded every month, except May and June (fig. 4). Additionally, the December monthly mean value exceeded the maximum for the period of record by 0.6oC. The monthly means for February, April, and August also were high but did not exceed their respective monthly maximums.

Figure 3. Monthly mean specific conductance at Delaware River at Trenton, New Jersey, water year 2002.

Figure 4. Monthly mean water temperature at Delaware River at Trenton, New Jersey, water year 2002.

Figure 3 Figure 4


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, 15.1 milligrams per liter (mg/L), occurred in January when the monthly mean water temperature was at its lowest, 2.6oC (fig. 5). The lowest monthly median of daily minimum DO concentrations, 8.8 mg/L, and the highest monthly mean water temperature, 27.0oC, occurred in July. No monthly medians of DO minimums and maximums during water year 2002 exceeded longterm extremes for the period of record.

Figure 5. Monthly medians of daily maximum and minimum dissolved oxygen concentrations at Delaware River at Trenton, New Jersey, water year 2002

Figure 5


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 112 stations located throughout the 20 WMAs. Five 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 107 stations are segregated into 5 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 waterquality database. Twenty-three Watershed-Integrator (WI) stations are located at the farthest downstream point, not affected by tide, in one of the large drainage basins in each WMA except two, WMA 9 and 16. The WI stations provide information on the sum of point and nonpoint source 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 statewide-status (SS) stations, two in each WMA, are chosen randomly to obtain a statistical basis that can be used to estimate values of water-quality indicators statewide. In water year 2002, five of the SS stations were co-located at existing WI or LUI stations; the data from the co-located stations are included in the statistical plots for the WI and LUI station categories. 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 2002 was to assess week-long diurnal physical measurements and constituent concentrations at three network stations located in the Passaic River basin. This is discussed further in Ambient Stream Monitoring Network Reconnaissance Study.

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; however, two stations were not sampled during the August to September period as a result of drought conditions and construction. 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 minimum reporting level (MRL) and laboratory reporting level (LRL). LRL was computed as twice the long-term method detection level (LT-MDL). Values reported by the analyzing laboratory as less than the MRL or LRL were included in each distribution but were reported as a value equal to one-half the MRL or the LT-MDL, respectively. Estimated values, which were determined to be greater than the LT-MDL but less than the LRL, were included. The estimated values are marked with an “E” in the water-quality tables. Refer to “Definition of Terms” in the “Introduction” for further explanation of these reporting conventions.

The record average ambient temperature for water year 2002 did not significantly affect median water temperatures when compared to those of previous water years. The median water temperatures for all the station types were within 3.25oC of each other (fig. 6). The remaining plots in figure 6 illustrate the relation between land use and water quality. Streams that drain urban areas seem to be negatively affected by wastewater discharges. In contrast, streams that drain background and undeveloped areas seemingly are not affected. The amount of dissolved and suspended organic matter in streams affect the concentrations of dissolved oxygen (DO), biochemical oxygen demand (BOD), and turbidity. Available DO is consumed during the biodegradation of organic matter; BOD is a measurement of this consumption. The lowest median DO concentration, 64.5 percent of saturation, the highest median BOD, 1.45 mg/L, and the highest median turbidity, 6.5 NTU, occurred at urban LUI stations. The highest median DO concentration, 95.5 percent of saturation, the lowest median BOD, 0.75 mg/L, and the lowest median turbidity, 1.1 NTU, occurred at background, undeveloped LUI, and background stations, respectively. Streams that are affected by wastewater discharges also are likely to have high levels of total dissolved solids (TDS); samples from urban LUI, WI, and agriculture LUI stations had the highest median concentrations of TDS, 278 mg/L, 196 mg/L, and 157 mg/L, respectively. The minimum median TDS concentrations occurred at background stations with 30 mg/L, followed by undeveloped LUI stations with 51 mg/L. Stream concentrations of TDS also are affected by streamflow. Concentrations of TDS greater than 500 mg/L occurred only at statewide status stations during November 2001 and February 2002, the severest part of the drought. The high levels of TDS at those particular stations were likely the result of solute concentration from extremely low streamflow.

Nutrients in streams are generally from anthropogenic sources. Nutrients are likely the result of runoff that contains chemical fertilizer and animal waste, and of discharge of municipal sewage. Nutrient enrichment subsequently causes an increase in phytoplankton, free floating algae, in streams. The presence of chlorophyll a, contained in phytoplankton, is therefore an indicator of nutrient enrichment. As expected, median concentrations of ammonia, nitrite plus nitrate, phosphorus, and chlorophyll a are higher in samples from mixed LUI, urban LUI, agriculture LUI, and integrator station types (fig. 6a). In contrast, median concentrations are lower in samples from background and undeveloped LUI station types. 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. Eutrophic urban streams have been found to have high levels of organic carbon caused by nutrient enrichment. The highest single value and median concentration of organic carbon occurred in samples from urban LUI stations. The highest single value was determined in a sample from a small urban stream that was stagnant until runoff from rainfall occurred the night prior to sampling. The water, both filtered and unfiltered, was reported as black in color. The lowest median concentration of DOC occurred in samples from background stations. Undeveloped LUI stations might be expected to have a low median concentration, but in fact, it is fairly high. Some undeveloped LUI stations were located on streams drain low relief cedar wetlands in the Coastal Plain physiographic province where the water has sufficient residence time to extract organic carbon compounds from decaying plant material.


Figure 6. Distribution of physical characteristics of, and constituent concentrations in, samples from 112 stations in the Ambient Stream Monitoring Network, water year 2002.

Figure 6 Figure 6a


Distribution, Detection Frequency, and Concentration of Selected Whole-Water Recoverable Trace Elements, Volatile Organic Compounds, and Filtered Pesticides in Samples from 46 Stations in the ASMN

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. For ease of discussion, only those constituents detected in one or more samples are shown in the figures or tables on pages 10 through 13. A detected constituent is one whose value is reported to be greater than or equal to the laboratory MRL or LRL. Values reported by the analyzing laboratory as “<” (less than the MRL or 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 “Definition of Terms” in the “Introduction” for more information about MRLs and LRLs.

Samples for the analysis of trace elements were collected at two background stations to develop a baseline with which to compare the water quality at other stations. Forty-four samples were collected from a random selection of long-term fixed station types. Every trace element in the USGS National Water Quality Laboratory schedule was detected in more than one sample and, therefore, was included in figure 7. Estimated values, concentrations below the LRL line in each plot, also were included. Barium, iron, manganese, and zinc were detected in 100 percent of the samples. Chromium and silver had the lowest percentages of detection, 16.7 and 18.7, respectively. In general, trace elements were detected more often in samples from mixed LUI and statewide status stations. They were detected less often and in smaller concentrations in samples from undeveloped LUI and background stations, which were located on reaches of streams that remain relatively unaffected by human activity.

Figure 7. Concentration and detection frequency of whole-water-recoverable trace elements detected in samples from 46 stations in the Ambient Stream Monitoring Network, water year 2002.

Figure 7

Concentrations of VOCs and pesticides in samples from background stations were determined to develop a baseline and from SS stations to provide a general overview of the water quality statewide and of the aerial distribution of these compounds. Samples from 6 background and 40 SS stations were analyzed for 34 VOCs. Ten compounds were detected in more than one sample and are presented in figure 8. Ten compounds were detected only once and are presented in table 1. Refer to individual station records for tables that list all the compounds. The most frequently detected VOCs in 46 samples were Methyl tert-butyl ether (MTBE), in 48 percent of samples; chloroform, in 24 percent; and tetrachloroethylene, in 11 percent. Chloroform and MTBE were the only two compounds detected in samples from background stations. Chloroform is a by-product of the disinfection of drinking water and wastewater by chlorination; MTBE is a gasoline additive.

Figure 8. Concentration and detection frequency of volatile organic compounds detected in samples from 46 stations in the Ambient Stream Monitoring Network, water year 2002.

Table 1. Concentration of volatile organic compounds detected only once in samples from 46 stations in the Ambient Stream Monitoring Network, water year 2002.

Figure 8 Table 1


Filtered samples from 6 background and 40 SS stations were analyzed for 47 pesticides by use of laboratory schedule 2001. Only compounds detected in one or more samples are included in figure 9 and tables 2 and 3. Refer to “Laboratory Measurements” in the “Introduction” for the complete list of those pesticides and the LRL for each compound. Estimated values, concentrations to the left of the LRL line in each plot in figure 9, also are included. Pesticides, in low concentrations, were widely distributed throughout the State; twenty-four compounds were detected at one or more SS stations. Six compounds also were detected at background stations, indicating that atmospheric deposition is a possible source. Four of the detected compounds are insecticides—Carbaryl, Chlorpyrifos, Diazinon, and Malathion. The remaining compounds are herbicides. The most frequently detected pesticides in 46 samples were Metolachlor, in 83 percent of samples; Atrazine, in 80 percent; Deethylatrazine (a degradation product of Atrazine), in 74 percent; and Prometon, in 50 percent. The six compounds detected at background stations are commonly used herbicides, with the exception of carbaryl, which is an insecticide.

Table 2. Detection frequency of selected pesticides in filtered samples from 46 stations in the Ambient Stream Monitoring Network, water year 2002.

Table 3. Concentration of pesticides detected only once in filtered samples from 46 stations in the Ambient Stream Monitoring Network, water year 2002.

Table 2 Table 3


Figure 9. Concentration and detection frequency of pesticides detected in filtered samples from 46 stations in the Ambient Stream Monitoring Network, water year 2002.

figure 9


Ambient Stream Monitoring Network Reconnaissance Study

The water year 2002 reconnaissance study documented the occurrence of base-flow extremes of continuously monitored water temperature, dissolved oxygen (DO) concentration, percent of dissolved oxygen saturation, specific conductance, and pH at three network stations in the Passaic River basin. In situ multi-constituent sensors, or monitors, recorded the occurrence and magnitude of diurnal variations that could not be observed during normal station visits, which generally took place between the hours of 8 a.m. and 2 p.m. The monitors were deployed for five 1-week periods during the summer months. Graphs of hourly values are included in the individual station records for Pompton River at Pompton Plains (01388500), Passaic River at Little Falls (01389500), and Saddle River at Lodi (01391500) (figs. 19-23, 27-31, and 32-36, respectively).

The Reconnaissance stations were placed in the Passaic River basin, the most intensely used river basin in the State, to better characterize fluctuations of the characteristics and the relation of the characteristics
to surface-water quality during a State-declared Drought Emergency with modified allowable passing flows in the basin (William Honachefsky, New Jersey Department of Environmental Protection, written commun., April 2003). Diurnal variation of DO during days of base flow and suppression of variation during days of higher flow were recorded at the three stations. About 1 inch of rain fell throughout the period June 10 to 14; subsequently, the monitors recorded relatively stable DO values (+/- 1 mg/L from the daily mean) during the period. Stable, low base-flow conditions were recorded during the first few days of two periods, June 24 to July 1 and July 16 to 23; subsequently, the monitors recorded wide variations (+/- 4 mg/L from the daily mean) during those times. Significant rainfall in the middle of the periods resulted in immediate suppression of diurnal fluctuation, which gradually resumed as flow returned to near base flow. The causes of diurnal DO fluctuation are photosynthesis and aerobic respiration. The process of photosynthesis is driven by sunlight and produces free oxygen, which causes an increase in DO levels during the day. The process of algal respiration consumes free oxygen and causes a decrease in DO levels during the night. High streamflow, which carries an increased load of suspended material, increases turbidity that effectively blocks sunlight, and interrupts the photosynthetic process.

Ground Water Quality

The USGS, in cooperation with the NJDEP, operates the Ambient Ground-Water-Quality Network
(AGWQN), which was designed to monitor the quality of ground water at or near the water table throughout the State. Shallow ground water is generally the first and most significantly affected part of the ground-water system, and the quality of this water is directly related to human activities at the land surface. The AGWQN is a long-term monitoring network with goals to assess the status of ground-water quality by examining the concentrations of various constituents that can be used as environmental indicators, assess water-quality trends by examining data collected on a 5-year cycle, determine the effects of land use on shallow groundwater quality, identify threats from nonpoint sources of contamination, and identify emerging or new environmental issues of concern to the public.

The network will consist of 150 shallow groundwater wells distributed throughout New Jersey within three land-use types. Sixty wells are, or will be 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). Every year approximately 30 sites are sampled in one or several of the five WMRs. The cycle of sampling all 150 wells will be completed every 5 years. Water year 2002 was the fourth year of operation of the first 5-year cycle of the AGWQN.

Because of the difficulty of locating suitable sites north of the fall line, only three wells were installed and sampled during water year 2002 (fig. 10). The first 5-year cycle, however, will most likely be finished by the end of water year 2003. Because few samples were collected, statistical analyses are not presented in this volume. Selected location, construction, and analytical data for the three wells are summarized in table 4. Samples from the wells were analyzed for physical characteristics, major ions, nutrients, trace elements, organic constituents, and gross alpha and beta radioactivity. The records of chemical constituents are in the section, “Water-Quality at Miscellaneous Ground-Water Sites.”

Figure 10. Location of sites in the Ambient Ground-Water-Quality Network, water year 2002.

Table 4. Hydrogeologic unit and land use at three wells sampled as part of U.S. Geological Survey-N.J. Department of Environmental Protection (cooperative) Ambient Ground-Water-Quality Network, water year 2002.
Figure 10 Table 4


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