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| Publications— Water Resources Investigations Report |
By R. Edward Hickman and Thomas H. Barringer
View the report in Portable Document Format (PDF) WRIR 98-4204 (10.4 MB)
Trend tests were conducted on values of 24 water-quality characteristics measured at 83 surface-water-quality stations on streams in New Jersey during water years 1986-95. Characteristics tested include physical properties and concentrations of nutrients, bacteria, and major dissolved constituents. Seasonal Kendall uncensored tests and tobit regression were used to determine whether unadjusted values of water quality or flow-adjusted values of water quality increased or decreased during this period.
Results of tests on instantaneous streamflow measured at the time of water-quality measurements indicate that streamflow decreased during the period of study; 20 of the 81 stations tested showed decreasing values of instantaneous streamflow. No station showed increasing values of instantaneous streamflow. Because the locations of stations with decreasing streamflow are widespread, it is likely that these trends are due to changes in weather patterns rather than to changes in the amount of water withdrawals.
Results of tests on nutrients are consistent with the expected effects of upgrades to sewage-treatment plants, which occurred in the State of New Jersey during the period of study. For all nutrients tested other than total nitrate plus nitrite, more stations showed decreasing unadjusted and flow-adjusted values than showed increasing unadjusted and flow-adjusted values.
Results for eight major dissolved constituents--specific conductance, total hardness, and dissolved concentrations of solids, sodium, potassium, calcium, magnesium, and chloride--of the nine tested showed more stations with increasing values than stations with decreasing values. Only dissolved sulfate did not show more increases than decreases.
Abstract
Introduction
Purpose and scope
Previous investigations
Description of the study area
Methods of analysis
Data selection and preparation
Preparation of unadjusted values of water-quality characteristics
Preparation of flow-adjusted values of water-quality characteristics
Trend analysis
Unadjusted values of water-quality characteristics
Uncensored data sets
Censored data sets
Flow-adjusted values of water-quality characteristics
Trends in water-quality characteristics of New Jersey streams
Summary and conclusions
References cited
Appendix 1. Methods used to estimate missing unadjusted values for selected water-quality characteristics
Appendixes 2-25. Summary statistics and results of trend tests for water-quality characteristics of selected surface-water-quality stations in New
Jersey, water years 1986-95
Instantaneous streamflow
Temperature
Dissolved oxygen
Dissolved oxygen (percent)
5-day biochemical-oxygen demand
pH
Total alkalinity
Total nitrogen
Total ammonia
Total organic nitrogen
Total nitrate plus nitrite
Total phosphorus
Total organic carbon
Fecal coliform (MPN)
Fecal coliform (COL)
Specific conductance
Dissolved solids
Dissolved sodium
Dissolved potassium
Total hardness
Dissolved calcium
Dissolved magnesium
Dissolved chloride
Dissolved sulfate
Suggested citation:
Hickman, R.E., and Barringer, T.H., 1999, Trends in water quality of New Jersey streams, water years 1986-95: U.S. Geological Survey
Water Resources Investigations Report 98-4204, 174 p.
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View the report in Portable Document Format (PDF) WRIR 98-4204 (10.4 MB)
For more information about USGS activities in New Jersey contact:
Director
USGS New Jersey Water Science Center
Mountain View Office Park
810 Bear Tavern Road, Suite 206
West Trenton, New Jersey 08628
Telephone: (609) 771-3900
Fax: (609) 771-3915
or access the USGS New Jersey Water Science Center home page at:
http://nj.usgs.gov/.
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