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New Jersey Water Science Center
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Summary of Annual Hydrologic Conditions - 2005
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 39.38 inches of precipitation during the 2005 water year (October 2004 to September 2005), making it the 25th driest water year since 1895. Monthly mean precipitation was below average for 7 months of the 2005 water year (fig. 1) (Monthly Precipitation in New Jersey, Office of the State Climatologist, Rutgers University; accessed at http://climate.rutgers.edu/stateclim_v1/data/ njhistprecip.html). Mean values for November and January were 1.37 and 0.86 inches above average, but values for October, May, August, and September were 1.09, 0.91, 2.89, and 2.52 inches below average, respectively. Overall, precipitation was 5.33 inches (12 percent) below average during the 2005 water year.
Water year 2005 was the 9th warmest year since 1895 with a statewide average ambient temperature of 12.1 oC, 0.9 oC above the long-term (1895-2004) mean for the State (Monthly Mean Temperatures in New Jersey, Office of the State Climatologist, Rutgers University; accessed at http://climate.rutgers.edu/stateclim_v1/data/ njhisttemp.html). Monthly ambient air temperatures were above long-term means for 8 months of the 2005 water year (fig. 2).
Monthly mean streamflow was near or above normal throughout the first half of the year (October through April) at three index gaging stations (fig. 3). Streamflow was below normal throughout the second half of the year (May through September) except at Folsom during July. No historic extremes were exceeded during the water year.
Streamflow had an inverse effect on specific conductance (SC), an indicator of solute concentration, which was measured at the continuous water-quality monitoring station on the Delaware River at Trenton. Monthly mean SC values were below long-term (1968-2004) monthly mean values during October, December, and January when streamflow was above normal (fig. 4). Similarly, monthly mean SC values were above long-term means during June through September when streamflow was below normal. Historic maximum values were tied in July and exceeded in June and August. SC values were not recorded on a daily basis during most of April and May because severe flooding affected the river intake at the monitoring location. Therefore, monthly mean SC values could not be computed for April and May.
Monthly mean water temperature values measured at the Delaware River at Trenton were above long-term mean monthly values during January, June, July, August, and September in water year 2005 (fig. 5). The historic maximum monthly mean value was exceeded in August. Mean ambient air temperatures were above normal during June through September.
Dissolved oxygen (DO) concentrations generally exhibit an inverse relation to water temperature. DO, therefore, varies seasonally. Yearly maximums occur in winter, and yearly minimums occur in summer. Daily variation of DO, affected by aquatic plant life and sunlight, sometimes overrides the yearly pattern. As expected, the lowest monthly median of daily minimum DO concentrations, 6.8 milligrams per liter (mg/L), occurred in July when the monthly mean water temperature was at its highest, 27.5 oC (fig. 6). The highest monthly median of daily maximum DO concentrations, 15.8 mg/L, occurred in March when warming water temperatures may have stimulated algal growth.
Ambient Surface-Water-Quality Monitoring Network
The U. S. Geological Survey (USGS), in cooperation with the New Jersey Department of Environmental Protection (NJDEP), operates the cooperative Ambient Surface-Water-Quality Monitoring Network (ASWQMN), 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 ASWQMN consists of as many as 119 stations located throughout the 20 WMAs. Four stations are located on the Delaware River main stem. Seven 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 2005, five of the SS stations were co-located at existing WI or LUI stations, reducing the number of total stations sampled to 114. 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 “Surface-Water-Quality Station Records” in this report. In addition to the regularly scheduled samples, a reconnaissance study was initiated in water year 2005 to document the 24-hour variability of various physical properties of water at six stations in the network. This is discussed further in “Ambient Surface-Water-Quality Monitoring Network Reconnaissance Study” in this summary.
Distribution and Concentration of Selected Constituents in Filtered and Unfiltered Surface Water from Stations in the ASWQMN
Physical characteristics and concentrations of filtered and unfiltered nutrients, filtered organic carbon, total dissolved solids (TDS, parameter code 70300, residue upon evaporation), and biochemical oxygen demand (BOD) were determined in samples from 110 stations in the ASWQMN. 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—also were included. Refer to “Definition of Terms” in 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 - were excluded.
Samples from agriculture-LUI, urban-LUI, or integrator stations had the lowest median level of DO in the growing season (May – October); the highest median levels of temperature, BOD, and turbidity; and the highest median concentrations of total dissolved solids (TDS), ammonia, ammonia-plus-organic nitrogen, nitrite-plus-nitrate, and phosphorus (fig. 7). In contrast, samples from background and undeveloped-LUI stations had the lowest median levels of temperature, BOD, and turbidity, and the lowest median concentrations of TDS, ammonia, ammonia-plus-organic nitrogen, nitrite-plus-nitrate, and phosphorus. [Concentrations of filtered ammonia were determined by two laboratories; values reported less than their respective LRL were censored to equal one-half the higher of the two LRLs.]
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 during 2005 were found in samples from undeveloped-LUI stations.
Distribution, Concentration, and Detection Frequency of Recoverable Trace Elements in Unfiltered Water and Bed Sediment, Nutrients and Organic Compounds in Bed Sediment, and Pesticides in Filtered Water from Selected Stations in the ASWQMN
Unfiltered samples for the analysis of recoverable trace elements (TE) were collected during February to March and August to September at 7 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. Filtered samples for the analysis of dissolved arsenic also were collected. TE detected in at least 75 percent of samples are presented in figure 8 (values reported less than the LRL were included in each distribution as a value equal to the LT-MDL; values reported as “E”— estimated to be greater than the LT-MDL but less than the LRL—also were included). In general, median concentrations were lower in samples from background stations, which are located on reaches of streams that remain relatively unaffected by human activity. TE detected in fewer than 75 percent of samples are presented in figure 9 (values reported by the analyzing laboratory as “<”—less than the LRL—were considered to be not detected and were excluded from these plots; values reported as “E”—estimated below the LRL—were included). Samples from background stations had the lowest frequencies of detection. Silver was not found in any sample from background stations, and mercury in just one.
Bed-sediment samples for the analysis of nutrients, trace elements, polycyclic aromatic hydrocarbons (PAHs), and total polychlorinated biphenyls (PCBs) were collected at low-flow conditions during August and September at 2 background and 20 SS stations. Two of the seven background stations are sampled for bed sediment each year and are resampled every third year. Twenty of the 42 SS stations were selected for sampling on the basis of the availability of bed sediment at each station. Ammonia-plus-organic nitrogen, phosphorus, and total carbon were detected in all samples; the lowest median concentrations were present in samples from SS stations (fig. 10). Arsenic, cadmium, chromium, cobalt, iron, lead, manganese, and nickel were detected in 100 percent of the samples (fig. 11). Selenium was detected the least. Of the 30 PAH compounds in the laboratory schedule, only those with surface-water-quality standards are shown in figure 12. Fluoranthene was the most frequently detected compound. Total PCBs and dibenz(a,h)anthracene were the least frequently detected compounds at 18 and 59 percent, respectively. PCBs were not detected in samples from either of the background stations.
Filtered samples for the analysis of pesticides (laboratory schedule 2001) were collected during May and June at 7 background and 41 SS stations. Only compounds detected in one or more samples are discussed here. Refer to “Laboratory Measurements” in “Explanation of Water-Quality Records” in this report for the complete list of compounds in the schedule and the LRL for each compound. Twenty-eight pesticides were detected in low concentrations and were widely distributed throughout the State; all 28 compounds were detected in samples from one or more SS stations (table 1). Five of the detected compounds are insecticides—Carbaryl, Carbofuran, Chlorpyrifos, Diazinon, and Dieldrin. The remaining compounds are herbicides or fungicides. Atrazine, Metolachlor, and 2-chloro-4-isopropylamino-6-amino-s-triazine (CIAT, a degradation product of atrazine) were the most frequently detected pesticides at 77, 58, and 58 percent, respectively. Only four compounds, all commonly used herbicides, were detected in samples from background stations.
Ambient Surface-Water-Quality Monitoring Network Reconnaissance Study
The 2005 reconnaissance study documented the 24-hour variability of continuously monitored DO concentration, DO percent of saturation, specific conductance, water temperature, and pH at six network stations during autumnal base-flow conditions. The stations are 01379580, Passaic River near Hanover Neck; 01382000, Passaic River at Two Bridges; 01393960, West Branch Rahway River at Northfield Ave. at West Orange; 01396800, Spruce Run at Clinton; 01408710, Jakes Branch at South Toms River; and 01464020, Assunpink Creek at Memorial Drive (Peace St) at Trenton. In-situ 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 – generally between the hours of 8 a.m. and 2 p.m. The monitors were deployed for 7-day periods during September and early October; readings were recorded hourly. Graphs of hourly values recorded at each station are included in “Surface-Water-Quality Station Records” in this report (figs. 28, 29, 34-36, and 39). The selection of reconnaissance stations was based on previous occurrences of DO super-saturation (greater than 120 percent of saturation), DO under-saturation (less than 60 percent of saturation), or exceedances of New Jersey surface-water-quality standards. Three stations exhibited diminished DO levels. At Passaic River near Hanover Neck, the minimum DO recorded during the period was 2.1 mg/L on Sept. 17 at 1800 hours. At WB Rahway River, the minimum recorded was 5.1 mg/L on Sept. 3 at 1200. At Jakes Branch, the minimum recorded was 6.6 mg/L on Oct. 7 at 0100 and 1000. The result of increased streamflow from precipitation can be seen in the data from Assunpink Creek at Trenton. DO, pH, and SC decreased and water temperature increased as daily mean discharge increased from 17 cubic feet per second (ft3/s) on Sept. 13, to 165 ft3/s on Sept.14.
Ambient Ground-Water-Quality Monitoring Network
The USGS, in cooperation with the NJDEP, operates the cooperative Ambient Ground-Water-Quality Monitoring Network (AGWQMN), 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 observation wells were sampled in water year 2005. Fourteen wells are located in the Lower Delaware WMR throughout WMAs 17-20, and 16 are located in the Atlantic Coastal WMR throughout WMAs 13-16. The wells have 2-inch polyvinyl chloride casings; range in depth from 8.0 to 49.0 feet; and represent three land-use types, nine water-chemistry types, and seven hydrogeologic units (table 2). Samples from the wells were analyzed for physical characteristics, major ions, nutrients, organic carbon, trace elements, volatile organic compounds, pesticides, and gross alpha and beta radioactivity. A summary of the water chemistry of the 30 wells is listed in table 2. Analytical records were tabulated by WMA and station number, and are located in “Ground-Water-Quality Station Records” in this report.
Distribution, Concentration, and Detection Frequency of Physical Measurements, Ions, and Nutrients in Filtered and Unfiltered Water from 30 Sites in the AGWQMN
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 of total cations or total anions in the two base triangles. 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.
Samples from wells in undeveloped areas had the lowest median temperature and concentrations of hardness and TDS, those in agricultural areas had the highest median temperature and concentration of hardness, and those in urban areas had the lowest median DO and highest median concentration of TDS (fig. 16). Medians and ranges of DOC concentrations were similar among the three land-use types – undeveloped, agriculture, and urban. The outlier value of 29.5 is associated with a well (395417074143401, 291402-DoubleTroubleMW60) located in a bog, 0.2 miles from Cedar Creek, in Double Trouble State Forest. The driller’s log notes a six-foot surface layer of organic matter. Concentrations, medians, and frequencies of detection of nutrients detected in filtered samples are presented in figure 17 (values reported as less than the LRL were excluded; values reported as estimated were included). Ammonia and orthophosphorus were detected infrequently. The highest median concentration of nitrite-plus-nitrate was present in samples from wells in agricultural areas.
Distribution, Concentration, and Detection Frequency of Trace Elements in Filtered Water from 30 Sites in the AGWQMN
The least frequently detected TEs in samples from wells in all land-use areas were silver, detected in no sample; antimony, detected in 3 percent of samples; and mercury, detected in 13 percent (fig. 18; silver not included). Antimony and mercury were not detected in any sample from wells in undeveloped areas. Each TE shown in figure 19 was detected in at least 85 percent of the samples (values reported as less than the LRL were included in each distribution as a value equal to the LT-MDL; values reported as estimated were included). Samples from wells in undeveloped areas had the lowest median concentrations of barium, boron, cadmium, copper, lead, manganese and nickel. Those in agricultural areas had the highest median concentration of copper as well as the highest concentrations (outliers) of aluminum, barium, beryllium, and lead. Those outliers represent a well located in a narrow wood line surrounded by cultivated fields. Samples from wells in urban areas had the highest concentrations of boron, cadmium, copper, manganese, nickel, and zinc. Several of those outliers represent a well located in a narrow grass strip surrounded by commercial properties and a highway.
Concentration and Detection Frequency of Pesticides in Filtered Water and VOCs in Unfiltered Water from 30 Sites in the AGWQMN
Filtered samples from 30 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 “Explanation of Water-Quality Records” in this report for the complete list of those pesticides and the LRL for each compound. Four pesticide compounds – all herbicides – were detected in more than one sample, and all but one detection were in samples from wells in agricultural areas (fig. 20). Atrazine was most frequently detected; it was present in 17 percent of the samples. Two herbicides were detected only once (table 3).
Samples from 30 wells were analyzed for 34 volatile organic compounds (VOCs). Only VOCs detected in one or more samples are included in the figure or table. Three compounds were detected in more than one sample (fig. 21). Chloroform (trichloromethane) was the most frequently detected VOC; it was present in 40 percent of the samples. Four VOCs were detected only once (table 4).
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