EVALUATION OF STREAMFLOW, WATER QUALITY, AND PERMITTED AND NONPERMITTED LOADS AND YIELDS IN THE RARITAN RIVER BASIN, NEW JERSEY, WATER YEARS 1991-98 By Robert G. Reiser ________________________________________________________________________ U.S. Geological Survey Water-Resources Investigations Report 03-4207 In cooperation with the NEW JERSEY WATER SUPPLY AUTHORITY West Trenton, New Jersey 2004 U.S. DEPARTMENT OF THE INTERIOR GALE A. NORTON, Secretary U.S. GEOLOGICAL SURVEY Charles G. Groat, Director The use of brand, trade, or firm names in this report is for identification purposes only, and does not constitute endorsement by the U.S. Government. For additional information Copies of this report can be write to: purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Mountain View Office Park Branch of Information Services 810 Bear Tavern Road Box 25286 West Trenton, NJ 08628 Denver, CO 80225-0286 CONTENTS Page Abstract..........................................................................................................................................................1 Introduction....................................................................................................................................................2 Purpose and scope ............................................................................................................................3 Description of study area..................................................................................................................5 Basin characteristics .........................................................................................................................7 Previous studies ................................................................................................................................9 Acknowledgments ..........................................................................................................................11 Methods of study .........................................................................................................................................11 Water-quality data...........................................................................................................................11 Selection of constituents....................................................................................................12 Quality assurance of data...................................................................................................16 Statistical methods..........................................................................................................................17 Computation of instream loads and yields .....................................................................................19 Permitted load....................................................................................................................20 Nonpermitted load.............................................................................................................20 Estimation of time of travel ............................................................................................................20 Estimation of velocities ..................................................................................................................21 Selection of regression methods .....................................................................................................22 Correlation analysis and multiple regression analysis....................................................................24 Evaluation of streamflow.............................................................................................................................26 Streamflow characteristics..............................................................................................................28 Comparison of recent streamflow data to historical streamflow and precipitation data ................29 Evaluation of water quality..........................................................................................................................30 Major ions, nutrients, and field characteristics...............................................................................30 Water-quality standards .....................................................................................................30 Phosphorus ...........................................................................................................31 Fecal coliform bacteria.........................................................................................32 Hardness ...............................................................................................................32 Water temperature ................................................................................................32 pH .........................................................................................................................33 Total suspended solids..........................................................................................33 Dissolved oxygen .................................................................................................33 Sodium..................................................................................................................33 Un-ionized ammonia ............................................................................................34 Other constituents.................................................................................................34 Exceedance of reference levels..........................................................................................34 Trends in water-quality characteristics..............................................................................34 Relation of constituent values to season and flow.............................................................39 Alkalinity..............................................................................................................39 Ammonia plus organic nitrogen (TKN) ...............................................................42 Biochemical oxygen demand ...............................................................................42 Chloride................................................................................................................42 Dissolved oxygen .................................................................................................48 Dissolved solids, total...........................................................................................52 Fecal coliform bacteria.........................................................................................52 Hardness ...............................................................................................................57 Nitrate plus nitrite.................................................................................................57 iii CONTENTS--Continued Page Organic carbon, total ............................................................................................62 pH .........................................................................................................................62 Phosphorus ...........................................................................................................66 Sodium..................................................................................................................70 Sulfate...................................................................................................................70 Total suspended solids..........................................................................................75 Un-ionized ammonia ............................................................................................75 Water temperature ................................................................................................79 Water-quality rating...........................................................................................................83 Relation of total suspended solids to other constituents....................................................83 Comparison of ground-water-quality data to surface-water-quality data.......................................83 Constituent concentrations in ground water and surface water......................................................85 Relation of land use and population density to water quality.........................................................88 Pesticides ........................................................................................................................................92 Relation to season, flow, and water-quality and drinking-water standards .......................92 Relation to land use ...........................................................................................................95 Volatile organic compounds ...........................................................................................................96 Relation to season..............................................................................................................96 Relation to land use ...........................................................................................................96 Relation to flow and land use in the Bound Brook subbasin.............................................97 Evaluation of total loads and yields.............................................................................................................97