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Summary of Annual Hydrologic Conditions - 2004
Volume 3: Water-Quality
Yearly Trend of Precipitation, Stream Discharge, and Physical Water-Quality Characteristics Monitored at Several Index Stations
New Jersey received a statewide average of 53.25 inches of precipitation during the 2004 water year (October 2003 to September 2004), making it the 15th wettest water year since 1895. Monthly precipitation was above long-term means for 7 months of the 2004 water year (fig. 1) (Statewide Monthly Precipitation 1895-2004, Climate Data, N.J. State Climatologist, Rutgers University; accessed at http://climate.rutgers.edu/stateclim_v1/data/index.html). January, February, March, May, and June had below-average precipitation; however, no deficit greater than 1.34 inches occurred. Overall, precipitation was 8.72 inches (20 percent) above average during the 2004 water year.
Water year 2004 was the 17th warmest year since 1895 with a statewide average ambient temperature of 53.3 oF (11.8oC), 1.2 oF above the long-term (1895-2003) mean for the State (Statewide Monthly Mean Temperatures 1895-2004, Climate Data). Monthly ambient air temperatures were above long-term means for 9 months of the 2004 water year (fig. 2).
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 (01411000) and Trenton (01463500), respectively (fig. 3). All three index stations recorded above normal streamflow during the first and last quarters of the water year.
The precipitation and streamflow surpluses during six months of water year 2004 and their diluting 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. 4). Monthly mean SC values, an indicator of solute concentrations, were below long-term (1968-2003) monthly mean values during October to January and August and September. In contrast, monthly mean SC values were above long-term (1968-2003) monthly mean values during periods of lower-than-normal streamflow, February to June. February’s monthly mean SC value of 252 μS/cm (microsiemens per centimeter) exceeded the previous highest February mean of 232 μS/cm and occurred during a month of below-average streamflow when runoff containing road salt was likely to be entering the river. August’s monthly mean value of 155 μS/cm was lower than the previous lowest August mean of 168 μS/cm and occurred during a month of above-average streamflow.
Monthly mean water temperature values measured at the Delaware River at Trenton were above the long-term mean monthly values during March to June in water year 2004 (fig. 5). Mean ambient air temperatures were above normal during this same period. Monthly mean values for October and August were lower than the previous lowest monthly means by 0.2 and 0.3 oC, respectively.
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 lowest monthly median of daily minimum DO concentrations, 7.2 mg/L (milligrams per liter, occurred in July when the monthly mean water temperature was at its highest, 25.7oC (fig. 6). The highest monthly median of daily maximum DO concentrations for the year, 16.2 mg/L, occurred in March. This is the highest median recorded in March for the period of record.
Ambient Stream Monitoring Network
The U. S. 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 118 stations located throughout the 20 WMAs. Four stations are located on the Delaware River main stem. 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 drainage 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 are chosen randomly to obtain a statistical basis that can be used to estimate values of water-quality indicators statewide. In water year 2004, two of the SS stations were co-located at existing WI or LUI stations reducing the number of total stations sampled to 116. Analytical results from water-column samples collected at each station and bed-sediment samples collected at a subset of stations were tabulated by station number and are located in the Surface-Water-Quality Station Records section of this report. In addition to the regularly scheduled samples, a reconnaissance study was initiated in water year 2004 to assess concentrations of volatile organic compounds (VOCs) at 10 current and 8 additional stations. This is discussed further in “Ambient Stream Monitoring Network Reconnaissance Study” in this summary.
Distribution and Concentration 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 116 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. Data from the stations on the Delaware river main stem - the border between New Jersey and Pennsylvania - are excluded from the plots.
The plots in figure 7 (7a) illustrate the relation between land use and water quality. Streams that drain urban and agricultural areas seem to have been negatively affected by wastewater discharges and overland runoff, respectively. They exhibited higher concentrations of most constituents. In contrast, streams that drained background and undeveloped areas exhibited lower concentrations of most constituents, except DOC. The highest median value of turbidity and the lowest median concentration of DO during the growing season occurred at urban-LUI stations. The highest median concentrations of total dissolved solids (TDS), ammonia plus organic nitrogen, ammonia, nitrite plus nitrate, and phosphorus were present in samples from agriculture-LUI or urban-LUI stations. The lowest median values of turbidity and the highest median concentration of DO during the growing season occurred at background or undeveloped-LUI stations. The lowest median concentrations of TDS, ammonia plus organic nitrogen, ammonia, nitrite plus nitrate, and phosphorus were present in samples from background or undeveloped-LUI 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 concentrations of DOC were present in samples from undeveloped-LUI and urban-LUI stations.
Distribution, Concentration, and Detection Frequency of Recoverable Trace Elements in Unfiltered Water and Bed Sediment, Nutrients and Organic Compounds in Bed Sediment, Volatile Organic Compounds in Unfiltered Water, and Pesticides in Filtered Water from Selected Stations in the ASMN
Water samples for the analysis of trace elements, VOCs, and pesticides were collected when the constituents were most likely to have been detected. Samples for trace elements were collected during February to March and August to September; VOCs during February to March; and pesticides during May to June. Samples of bed sediment were collected in low-water conditions during August to September. For ease of discussion, only those constituents detected in one or more samples are shown in the figures or tables on pages 10 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 areal distribution of these compounds. Every trace element analyzed for was detected in one or more samples and, therefore, was included in figure 8. Barium, iron, manganese, and nickel were detected in 100 percent of the samples; boron, copper, and zinc were detected in all but a few. Chromium, arsenic, mercury, and silver had the lowest percentages of detection in samples from both background and SS stations- 36, 32, 15, and 1 percent, respectively. Mercury and silver were not detected in any sample from background stations. In general, median detected concentrations were lower 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, 12 SS, 7 WI, and 1 Delaware River main stem stations. Two of the six background stations are sampled for bed sediment each year and are resampled every third year. In water year 2004, 12 of the 42 SS stations were selected for sampling on the basis of the availability of bed sediment at each station. Seven stations were chosen from among the 23 WI stations. Data from the single Delaware River station was not included in this discussion. Ammonia plus organic nitrogen, phosphorus, and total carbon were detected in all samples; the lowest median concentrations were present in samples from background stations (fig. 9). Cobalt, iron, lead, manganese, and nickel were detected in 100 percent of the samples (fig. 10). Selenium had the lowest percentage of detection. Analytical results for mercury in bed sediment were pending approval at the time of publication. Of the 30 PAHs in the laboratory schedule, only those compounds with surface-water-quality standards are shown in figure 11. Pyrene and fluoranthene were detected in all samples. Dibenz(a,h)anthracene and phenanthrene were the least frequently detected compounds at 43 and 29 percent, respectively. Six compounds were not detected in samples from either of the background stations.
Filtered samples from 6 background and 42 SS stations were analyzed for 66 pesticides by use of laboratory schedule 2060. Only compounds detected in one or more samples are included in table 1. 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-nine pesticides were detected in low concentrations and were widely distributed throughout the State. All 29 compounds were detected in samples from one or more SS stations, but only two compounds, Atrazine and Imazethapyr, were detected in samples from background stations. Six of the detected compounds are insecticides—Caffeine, Carbaryl, Carbofuran, Imadacloprid, Methiocarb, and Oxamyl. The remaining compounds are herbicides or fungicides. Atrazine, 2,4-D, and Carbaryl were the most frequently detected pesticides at 52, 46, and 38 percent, respectively. The two compounds detected at background stations are commonly used herbicides.
Ambient Stream Monitoring Network Reconnaissance Study
The focus of the reconnaissance study during the 2004 water year was VOC sampling at 18 current or historic SS stations in the ASMN. Samples were collected at eight historic SS stations that had previous exceedances of in-stream VOC standards. Samples also were collected at 10 current-year SS stations within the same WMAs as the 8 sites with previous exceedances. Samples from previous years were analyzed for the presence of 34 compounds; samples from this year’s targeted study were analyzed for the presence of 61 compounds. Only 8 of the 61 were detected in more than one sample (fig. 12), and 2 were detected only once (table 2). The most frequently detected VOC in 18 samples was Methyl tert-butyl ether (MTBE), at 78 percent.
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).
Fifty-two observation wells were sampled in water year 2004. Four wells are located in the Passaic WMR in WMAs 3-6. Four are located in the Raritan WMR in WMAs 7, 9, and 10. Four are located in the Upper Delaware WMR in WMAs 1, 2, and 11. Twenty-eight are located in the Lower Delaware WMR in WMAs 17-20. Two are located in the Atlantic Coastal WMR in WMAs 15 and 16. The wells have 2-inch polyvinyl chloride casings; range in depth from 7.6 to 97.1 feet; and represent 3 land-use types, 10 water-chemistry types, and 11 hydrogeologic units (table 3). Samples from the wells were analyzed for physical characteristics, major ions, nutrients, organic carbon, trace elements, VOCs, pesticides, and gross alpha and beta radioactivity. A summary of the water chemistry of the 52 wells is listed in table 3. Analytical records were tabulated by WMR and site number, and are located in the Ground-Water-Quality Site Records section of this report.
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 box plot as a value equal to the LT-MDL or one-half the MRL, respectively, but were excluded from the scatter plots. Values reported as “E”—estimated to be greater than the LT-MDL but less than the LRL—were included in both types of plots. Refer to the Definition of Terms section of this report for further explanation of these reporting conventions.
Distribution, Concentration, and Detection Frequency of Physical Measurements, Ions, and Nutrients in Filtered and Unfiltered Water from 52 Sites in the AGWQN
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. 13, 14, 15). 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.
The median concentrations of hardness and TDS were lowest in samples from wells in undeveloped areas and highest in samples from wells in urban areas (fig. 16). The lowest concentrations of nutrients were found in samples from wells in undeveloped areas (fig. 17). The highest concentrations and median values of nitrite plus nitrate and orthophosphorus were found in samples from wells in agricultural areas.
Distribution, Concentration, and Detection Frequency of Trace Elements in Filtered Water from 52 Sites in the AGWQN
The least frequently detected trace elements in samples from wells in all land-use areas were mercury, detected in 15 percent of samples, and antimony, detected in 12 percent (fig. 18). Antimony, mercury, and thallium were not detected in any sample from wells in undeveloped areas. The trace elements shown in figure 19 were detected in all 52 samples. The highest median concentrations of aluminum and cadmium were present in samples from wells in agricultural areas. The highest median concentrations of barium, boron, and manganese were present in samples from wells in urban areas.
Concentration and Detection Frequency of Pesticides in Filtered Water and VOCs in Unfiltered Water from 52 Sites in the AGWQN
Filtered samples from 52 wells were analyzed for 52 pesticides by use of USGS National Water Quality Laboratory schedule 2001. Only pesticides detected in one or more samples are included in the figure or table. Refer to “Laboratory Measurements” in the Explanation of Water-Quality Records section of this report for the complete list of those pesticides and the LRL for each compound. Nineteen pesticide compounds were detected in samples from the 52 wells. Those compounds detected only once are listed in Table 4. In general, there were more detections in samples from wells in agricultural areas than other land-use areas; there were no detections in samples from wells in undeveloped areas (fig. 20). The most frequently detected herbicides in samples from wells in agricultural and urban areas were Atrazine, 2-Chloro-4-isopropylamino-6-amino-s-triazine (CIAT)—a degradation product of Atrazine—, and Metolachlor at 35, 27, and 23 percent, respectively. Insecticides Dieldrin, Fipronil, and Carbaryl were detected infrequently.
Samples from 52 wells were analyzed for 34 VOCs. Only VOCs detected in one or more samples are included in the figure or table. Those compounds detected only once are listed in table 5. Samples from wells in urban areas had the most detections; samples from wells in undeveloped areas had a single detection (fig. 21). The most frequently detected VOCs in samples from wells located in all land-use areas were MTBE, detected in 35 percent of samples, and Chloroform, detected in 19 percent.