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Water in the Delaware River at Trenton, N.J., is a mixture of several types water from the mountainous headwater region, water from the coal-mining regions, and water from the limestone valleys. The quantities of these types of water, in relation to the total quantity of water at Trenton, vary with changes in season and reservoir releases. The chemical quality of the water during the 17-year period 1945-61 was excellent, and the water was suitable for most uses after little or no treatment. The average concentration of dissolved solids was 86 ppm (parts per million), and 90 percent of the time it ranged from 57 to 126 ppm. Usually the pH of the water was close to 7.0 (considered to be a neutral point neither acid nor alkaline) . The hardness was less than 86 ppm 95 percent of the time. The general composition of the dissolved-solids content, in terms of equivalents, is 28 percent calcium, 14 percent magnesium, 8 percent sodium plus potassium, 43 percent bicarbonate plus sulfate, 5 percent chloride, and 2 percent nitrate. Concentrations of minerals in the river water are lowest during March, April and May (median concentration of dissolved solids, 66 ppm) and are highest during August and September (median, 107 ppm). Each year an average of 880,000 tons of dissolved solids and 932,000 tons of suspended solids are carried past Trenton by the Delaware River. The greatest monthly loads of dissolved solids are in March and April, and the smallest are from July to October. Suspended-solids loads are greater when the streamflow is high but small the rest of the time. Concentration of suspended solids exceeds 100 ppm only 5 percent of the time. The headwaters in the Delaware River basin are the source of water of excellent quality. Much of this water is stored in reservoirs, and when released during August and September, it improves the quality of the water at Trenton. These releases to augment low flow have the effect of narrowing the range of concentrations of dissolved constitutents. In 1952 and 1962, 6 and 19 percent, respectively, of the drainage area above Trenton was regulated by reservoirs. After proposed construction, 60 percent will be regulated by 1975. Thus, it may be that the high concentrations of dissolved constituents observed in the 1945-61 period will not occur again. XI X2 CONTRIBUTIONS TO THE HYDROLOGY OF THE UNITED STATES It is probable that the water quality observed during the period 1945-61 (dissolved solids 57-126 ppm 90 percent of the time, pH close to 7.0, hardness less than 86 ppm 95 percent of the time) is representative of what can be expected in the future, for a variety of hydrologic conditions were experienced in the 17-year period. INTRODUCTION The Delaware Eiver is important to 23 million people in four States, for the economy of the area depends in part on the water potential of the river. Although the quantity is significant, the quality of the water determines its value for domestic and industrial uses. Therefore, any comprehensive plan for management of the basin's water must be concerned with the quality as well as the quantity. The purpose of this report is to describe the chemical quality of the Delaware Eiver water at Trenton; to identify the hydrologic, geologic, and cultural factors that are responsible for variations in the quality; and to speculate on possible future changes in the water quality. Trenton is the farthest downstream point at which the water of the Delaware Eiver has continuously been gaged. Below Trenton the river is tidal, and the fresh water mixes with salty ocean water. Analyses of water at Trenton reflect changes in water quality in the upstream part of the basin. These analyses also characterize the inflow of water and its principal constituents, including sediment as well as dissolved minerals, into the tidal estuary. Tidal mixing, upstream as well as downstream velocities, numerous effluents from municipalities and industries along both banks, and other factors make analysis of water quality in the tidal estuary very complex. The U.S. Geological Survey has measured streamflow at Trenton continuously since October 1912 and has collected and analyzed water samples since October 1944. During the IT years from October 1944; through September 1961, over 6,200 daily samples have been collected, of which 534: composites have been analyzed. In this report the results of these analyses are summarized, and both the typical water quality and the extent of variation from the typical are described. The environment which causes these changes is also discussed, and the effects on water quality that are caused by drought, flood, reservoir operation, streamflow regulation, and population increase are indicated. Plans have been initiated to develop the water resources of the basin more fully through the construction of reservoirs. The facts given in this report will be helpful to the orderly management of the basin's water resources. PRIOR STUDIES Several comprehensive studies of the Delaware Kiver basin have been made, but, in general, they have reported little on water quality QUALITY, DELAWARE EWER WATER, TRENTON, N.J. X3 in the fresh-water part of the basin. In 1933 the U.S. Army Corps of Engineers completed the so-called 308 report. This report dealt with navigation, hydroelectric power, flood control, irrigation, and water supply; but it gave no recommendations for the development of the water resources. The Committee on Public Works of the U.S. Senate directed in April 1950 that the 308 report be reviewed by the Corps of Engineers to determine the extent to which updating was necessary. Subsequently, two hydrologic events occurred in the Delaware River basin that gave impetus to the review of this report. In August 1955 a disastrous flood caused a loss of more than 100 lives and caused property damage in excess of $100 million. In 1957 an intense 6-month drought affected the quality of water in the tidal part of the river, and the salinity front moved upstream to Philadelphia. These events emphasized the need for a more comprehensive study of the water resources of the Delaware basin. To help them carry out the Congressional directive, the Corps of Engineers established the Delaware River Basin Survey Coordinating Committee, which included representatives from Federal agencies and from the States of New York, Pennsylvania, New Jersey, and Delaware, as well as the cities of New York and Philadelphia. Specific assignments were delegated to various Federal, State, and city agencies for certain studies to be included in the corps' comprehensive report. The coordinating committee periodically reviewed the progress of the agencies' studies and worked in close cooperation with the corps' Valley Report Group, which was responsible for reviewing, preparing, editing, and publishing the finished report. The results of the investigation were published in 1960 in the "Report on the Comprehensive Survey of the Water Resources of the Delaware River Basin," hereinafter referred to as the "comprehensive report." Volume 1 of that report summarizes the significant features of the survey and presents a long-range plan for the development of the water resources of the Delaware River basin. In 25 appendixes, the corps and the cooperating agencies discuss in detail flood control, navigation, geology, hydroelectric power, recreation, fish and wildlife, water supply, and present and estimated future demands on the water resources of the basin to the year 2010. Much information about the flow and water quality at Trenton is given in the report and appendixes. ACKNOWLEDGMENTS The quality-of-water investigations of the Delaware River basin above Trenton have principally been centered around the main stem Delaware River and its tributaries in Pennsylvania. Cooperative funds for the project were furnished by the Pennsylvania Department of Commerce from October 1944 to September 1954 and from October X4 CONTRIBUTIONS TO THE HYDROLOGY OF THE UNITED STATES 1956 to September 1958; by the Pennsylvania Department of Forests and Waters from October 1958 to 1963; and, for the chemical-quality sampling station at Trenton, by the Philadelphia Water Department since October 1954. Since October 1961, cooperative funds for investigating the chemical quality of New Jersey tributaries have been furnished by four agencies of the State of New Jersey. Chemical-quality investigations were conducted under the general supervision of W. F. White, Jr., district chemist 1944-52, and N. H. Beamer, district chemist 1952-64, Water Eesources Division, U.S. Geological Survey. The results for 1944^51 were published by the Pennsylvania Department of Commerce State Planning Board, and the Pennsylvania Department of Forests and Waters (1947, 1951,1953). Some of the data on water quality at Trenton were discussed by Durf or and Keighton (1954) and by Durf or and Anderson (1963). Parker and others (1964) dealt comprehensively with the geology and hydrology of the basin, the chemical quality of the ground water and surface water, and the water-supply problems of the basin. The Delaware Eiver Master has provided records of streamflow regulation and reservoir operation, and has assisted in the collection of water samples in the upper basin since 1954. |
