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Summary of Annual Hydrologic Conditions - 2001
Volume 3: Water-Quality
Yearly Trend of Precipitation, Stream Discharge, and Physical Water-Quality Characteristics Monitored at Several Index Stations
New Jersey received 39.12 inches of precipitation during water year 2001 (October 2000 to September 2001); precipitation was calculated from a spatially weighted average at several dozen stations throughout the State. This is a 5.68-inch (13 percent) deficit when compared to the long-term (1895-2000) mean-yearly value of 44.80 inches (Statewide Monthly Precipitation 1895-2001, Climate Data, N.J. State Climatologist, Rutgers University; accessed at http://climate.rutgers.edu/stateclim/data/index.html). Monthly mean values for March and June were above long-term (1895-2000) mean-monthly values; October, January, February, April, May, and July to September were below long-term means, whereas November and December were near normal (fig. 1). Streamflow was above average during March and June at the High Bridge and Folsom index stations and during December, April, and June at the Trenton index station (fig. 2). Below-average streamflow was recorded during November, January, May, and July to September at all three index stations.
One effect of the yearlong precipitation deficit can be seen in the plot of monthly mean values of specific conductance (SC) at the continuous-monitoring station on the Delaware River at Trenton (fig. 3). All monthly mean values of SC for the 2001 water year were above long-term (1968-2000) mean-monthly values. The values for May and July exceeded the highest monthly mean values for the period of record; values for February, March, and August were within 3 µS/cm (microsiemens per centimeter at 25 degrees Celsius) of period-of-record maximum values. Near-average monthly mean SC values recorded during April and June correspond to above average streamflow during these months. SC is generally inversely related to stream discharge and is often used as an indicator of dissolved solids concentration.
The spatially weighted average ambient temperature for New Jersey for the 2001 water year was 52.5°F (11.4°C); the long-term (1895-2000) mean-yearly temperature was 52.1°F (11.2°C) (Statewide Monthly Mean Temperatures 1895-2001, Climate Data, N.J. State Climatologist, Rutgers University; accessed at http://climate.rutgers.edu/stateclim/data/index.html). Most water temperatures measured throughout the year at stations in the Ambient Stream Monitoring Network (described later in this section) were within previously measured maximums and minimums. Monthly mean water temperature values for water year 2001 measured at Delaware River at Trenton, New Jersey, closely matched long-term (1895-2000) mean-monthly values and did not exceed period-of-record minimums or maximums (fig. 4).
Dissolved oxygen (DO) concentration generally exhibits 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 the daily maximum DO concentrations, 15.4 mg/L (milligrams per liter), occurred in February when the mean water temperature was 2.7°C (fig. 5). The lowest monthly median of the daily-minimum DO concentrations, 7.4 mg/L, and the highest monthly mean water temperature, 26.9°C, occurred in August. No monthly medians of daily maximum or minimum values for water year 2001 exceeded previously established highest or lowest monthly median values 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 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 descriptive statistics 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 water-quality 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 areas 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 2001, five of the SS stations were co-located at existing WI or LUI stations; data from both station types were included in the statistics of both station types. 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 2001 was to assess 3 to 6 day diurnal physical measurements and constituent concentrations at a subset of the network sites. 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
Measurements were made of physical characteristics of, and analyses were conducted to determine concentrations of total and filtered nutrients, filtered common ions, filtered organic carbon, and biochemical oxygen demand (BOD) in, water 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 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 LT-MDL. Estimated values, which were determined to be greater than the LT-MDL but less than the LRL, also were included, and they are marked with an "E" in the water-quality tables. Refer to "Laboratory Measurements" in the "Introduction" for additional information on reporting limits and estimated concentrations.
The highest median water temperature and lowest median percent of dissolved oxygen saturation during the growing season (April-October) occurred at urban LUI stations (fig. 6a and fig. 6b). Streams affected by wastewater and road salt runoff 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-252, 174, and 152 mg/L, respectively. In contrast, samples from undeveloped LUI and background stations had the lowest median concentrations, 49 and 73 mg/L, respectively. Samples from SS stations had the most outliers greater than 400 mg/L of TDS. The two highest values, 1,700 and 4,190 mg/L, were from samples collected the day after a snowfall and the subsequent application of road salt. The lowest median concentration of BOD, 0.5 mg/L, was present in samples from background stations and is lower than the minimum reporting level of 1.0 mg/L.
Runoff containing chemical fertilizer or animal waste, and discharge of municipal sewage, are likely contributors of nutrients to streams. The highest median concentrations of ammonia, as nitrogen, were present in samples from urban and agriculture LUI stations, 0.095 and 0.060 mg/L, respectively. The highest median concentrations of nitrite plus nitrate, as nitrogen, were present in samples from agriculture LUI and WI stations, 1.50 and 1.25 mg/L, respectively. The highest median concentrations of ammonia plus organic nitrogen were present in sample from urban and agriculture LUI stations, 0.52 and 0.42 mg/L, respectively. The highest median concentrations of phosphorous were present in samples from urban LUI and WI stations, 0.070 and 0.066 mg/L, respectively. Samples from background and undeveloped LUI stations contained the lowest median concentrations of the four nutrient species.
The median concentration of filtered organic carbon in samples from network stations of all types for water years 1998-2000 is 3.7 mg/L. Median values measured in samples during water year 2001 ranged from 2.0 at background stations to 4.8 mg/L at undeveloped LUI stations. Some undeveloped LUI stations were located on streams that drained 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. Predictably, samples from undeveloped LUI stations had the largest range of filtered organic carbon concentrations, 1.4 to 19.0 mg/L, and the highest median concentration, 4.8 mg/L.
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
Concentrations of trace elements, volatile organic compounds (VOCs), and pesticides in samples from background stations were determined to develop a baseline with which to compare the water quality at other stations and at SS stations to provide a general overview of water quality statewide and of the aerial distribution of these compounds. Samples for analysis of trace elements, VOCs, and pesticides were collected during the period when the constituents were most likely to be 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. A detected constituent was one whose value is reported to be greater than or equal to the laboratory MRL or LRL. Data on selected whole-water-recoverable trace elements with a high percentage of detection in samples (greater than 75 percent) are summarized in box plots; data on constituents with a lower percentage of detection in samples are summarized in scatter plots. Values reported by the analyzing laboratory as less than the MRL or LRL were included in the box plots but were reported as a value equal to one-half the MRL or LT-MDL; they were excluded from the scatter plots. Estimated values were included in both types of plots.
Abundant minor elements, iron and manganese, and less abundant trace elements that might affect human health, and plant nutrition and toxicity (Hem, 1985), were detected less often and in smaller concentrations in samples from background stations than in samples from SS stations (figs. 7 and 8). Arsenic, chromium, mercury, and silver were not detected in any sample from background stations; lead, nickel, and selenium were detected once each. Median concentrations of minor elements and detection frequencies of trace elements were greatest in samples from SS stations.
Samples from 6 background and 40 SS stations were analyzed for 34 VOCs. Only those detected in one or more samples are included in figure 9 and table 1. (See individual station records for tables listing all the compounds.) Five compounds were detected once, and eight were detected multiple times. The most frequently detected VOCs in 46 samples were Methyl tert-butyl ether (MTBE), in 35 percent of samples and chloroform, in 28 percent. Chloroform was the only compound detected in samples from background stations. Chloroform and Bromodicholoromethane are by-products of the chlorination of drinking water. Benzene and Toluene are components of gasoline; MTBE is a gasoline additive.
Filtered samples from 6 background and 40 SS stations were analyzed for 47 pesticides by use of USGS National Water Quality Laboratory schedule 2001. Only compounds detected in one or more samples are included in figure 10 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 lines in figure 10, also are included. Twenty-nine pesticides were detected at one or more SS stations; six of these also were detected at background stations. Seven of the detected compounds are insecticides-Chlorpyrifos, Diazinon, Malathion, Carbaryl, Carbofuran, Dieldrin, and Lindane. The remaining compounds are herbicides. The most frequently detected pesticides in 46 samples were Atrazine, in 76 percent of samples; Metolachlor, in 74 percent; Prometon, in 54 percent; Deethylatrazine (a degradation product of Atrazine), in 52 percent; Carbaryl, in 43 percent; and Diazinon and Simazine, in 39 percent each. The six compounds detected at background stations are commonly used herbicides. The two most frequently detected at background stations were Metolachlor, in 50 percent of samples with a median concentration 0.002 µg/L (micrograms per liter) and Atrazine, in 33 percent with a median concentration of 0.006 µg/L. The median concentrations of Metolachlor and Atrazine in samples from SS stations were 0.006 and 0.009 µg/L, respectively.
Ambient Stream Monitoring Network Reconnaissance Study
For the reconnaissance study done in water year 2001, base-flow extremes of continuously monitored water temperature, dissolved oxygen concentration, percent of dissolved oxygen saturation, specific conductance, and pH were measured during periods of less than 1 week. 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., were documented. The continuous measurements were made by insitu multi-constituent sensors, or monitors, deployed from 3 to 6 days at 24 network stations during the summer months. Values were recorded hourly. Statistical summaries for the periods of record for all stations are shown in figure 11a and 11b; graphs of hourly values are included in the individual station records.
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). One background station was included as a control for comparison with other stations and to demonstrate constituent variations in pristine watersheds. Other station types represented are undeveloped LUI (two), agriculture LUI (four), urban LUI (five), WI (eight), and SS (four).
Mean values for percent-of-DO-saturation above 100 percent, for the periods of record, occurred at undeveloped LUI station 01440000 (Flat Brook at Flatbrookville) and WI stations 01398102 (South Branch Raritan River at South Branch) and 01457400 (Musconetcong River at Riegelsville). Additionally, maximum values for percent-of-DO-saturation above 120 percent, for the periods of record, occurred at WI stations 01391500 (Saddle River at Lodi) and 01399780 (Lamington River at Burnt Mills). Mean values for percent-of-DO-saturation below 60 percent, for the periods of record, occurred at urban-LUI stations 01403385 (Bound Brook at Middlesex) and 01463850 (Miry Run at Mercerville), WI station 01402000 (Millstone River at Blackwells Mill), and SS station 01482530 (Major Run at Sharptown). Additionally, minimum percent-of-DO-saturation below 60 percent, for the periods of record, occurred at undeveloped, urban, and agriculture LUI stations 01411400 (Fishing Creek at Rio Grande), 01467359 (North Branch Big Timber Creek at Glendora), and 01482500 (Salem River at Woodstown); WI station 01391500; and SS station 01391550 (Saddle River at Garfield).
SC and pH measurements at some stations exhibited diurnal variation. When respiring, plants and algae release carbon dioxide; it is quickly converted to bicarbonate, affecting SC and pH levels. Diurnal variation and high values of pH occurred at WI stations 01391500, 01398102, and 01399780; and undeveloped LUI station 01440000. Diurnal variation of SC occurred at WI stations 01391500 and 01398102. Non-diurnal, period-long fluctuations of SC caused by specific events or conditions like rainfall, poor mixing, or diminishing stream discharge occurred at WI stations 01395000 (Rahway River at Rahway) and 01399780 and urban LUI stations 01394500 (Rahway River at Springfield) and 01463850.
The United States Geological Survey (USGS) in cooperation with the New Jersey Department of Environmental Protection (NJDEP), operates the Ambient Ground-Water-Quality Network (AGWQN), which is 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 ground-water 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 ground-water 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 2001 was the third year of operation of the first 5-year cycle of the AGWQN.
Thirty shallow wells were sampled in water year 2001. Fifteen wells are located in the Upper Delaware WMR, in WMAs 1, 2, and 11 (fig. 12). Four are located in the Raritan WMR, in WMAs 9 and 10. Eleven are located in the Atlantic Coastal WMR, in WMAs 12-14. The wells have 2-inch polyvinyl-chloride casings, range in depth from 10 to 58 feet, and represent 3 land-use types, 8 water-chemistry types, and 13 hydrogeologic units (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."
Distribution, Detection Frequency, and Concentration of Selected Constituents in Filtered Samples from 30 Sites in the AGWQN
Measurements were made of physical characteristics of, and analyses were conducted to determine concentrations of filtered nutrients, common ions, trace elements, and organic carbon in, water samples from 30 wells in the AGWQN. Data on nutrients and trace elements with a high percentage of detection in samples (greater than 75 percent) are summarized in box plots; data on constituents with a lower percentage of detection in samples are summarized in scatter plots. Values reported by the analyzing laboratory as less than the MRL or LRL were included in the box plots but were reported as a value equal to one-half the MRL or LT-MDL; they were excluded from the scatter plots. Estimated values were included in both types of plots.
Similarity in ground-water chemistry among wells located in areas with agriculture, undeveloped, and urban land-use designations is suggested by the data summarized in figures 13 and 14. The median values of most constituents were present in similar concentrations in samples from wells in different areas, with some exceptions. The lowest median concentrations of nitrite plus nitrate and manganese, and the highest median concentration of filtered organic carbon were present in samples from wells in undeveloped areas. The highest median concentrations of aluminum and nickel were present in samples from urban areas. As a result of agricultural practices, the highest median concentrations of hardness and nitrite plus nitrate were present in samples from agriculture areas. Orthophosphorus was detected in only 20 percent of the 30 samples (fig. 18); this frequency was the lowest for the nutrients that were analyzed for.
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 or Piper diagrams (figs. 15 to 17). These diagrams and the "Water Type" column (column 5) in table 4 are grouped by land-use type and the major ion chemistry of the water from similar land-use areas is summarized.
Silver is not included in figure 19 because this trace element was not detected in any of the 30 samples. Mercury was detected in one sample (urban). Lead and zinc were detected in 70 percent of the samples; the same number of detections of lead and zinc occurred in samples from each land-use type.
Concentration and Detection Frequency of Selected Organic Constituents in Filtered Samples from 30 Sites in the AGWQN
Samples from 30 wells were analyzed for 34 VOCs. Only those detected in one or more samples are listed in table 5. (See individual station records for tables listing all the compounds.) Estimated values are included. The most frequently detected VOCs in samples from wells located in all land-use areas were Chloroform and Methyl tert-butyl ether (20 percent each). They were most often detected in samples from urban areas (5 of 12). Cis-1, 2-dichloroethene was detected twice. The remaining compounds in table 5 were detected once. The highest total number of VOC detections (15 detections in 12 samples) occurred in samples from wells in urban areas, followed by undeveloped (5 in 9), and agriculture (2 in 9).
Filtered samples from 30 wells were analyzed for 47 pesticides by use of USGS National Water Quality Laboratory schedule 2001. Only pesticides detected in one or more samples are included in figure 20 or tables 6 and 7. (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 lines in figure 20, are included. Only 10 pesticide compounds were detected in samples from the 30 wells. The most frequently detected pesticides in samples from wells located in all land-use areas were the herbicides Metolachlor, in 27 percent of samples; Atrazine and Deethylatrazine, in 23 percent each; and Prometon, in 13 percent. Chlorpyrifos and Dieldrin were the only insecticides detected, only once each. Samples from wells in agriculture land-use areas had the highest total number of pesticide detections, 17 in 9 samples. Pesticides were detected 10 times in 12 samples from urban land-use areas, and 5 times in 9 samples from undeveloped areas.