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USGS1965

Hydrology of melt-water channels in southwestern Minnesota

Melt-water channel deposits are among the most important aquifers in southwestern Minnesota, but permeable zones within the deposits are difficult to locate. Interpretation of the depositional history of proglacial channel deposits from aerial photographs and test-hole samples indicates the position of the permeable zones. Generally, the coarse-grained deposits are in headwater areas, near the confluence of two channels, in bends, or at the junction of sluiceways. Locally, these deposits yield as much as 1,000 gallons per minute to wells.

Minnesota↗
USGS1965

Delaware River water quality Bristol to Marcus Hook, Pennsylvania, August 1949 to December 1963

During the 14-year period from August 1949 to July 1963, the U.S. Geological Survey, in cooperation with the city of Philadelphia, collected samples of river water once each month in the 43-mile reach of the Delaware River from Bristol to Marcus Hook, Pa., and daily at Trenton, 10 miles upstream from Bristol. This part of the Delaware is an estuary into which salt water is brought by tides; fresh water flows into the estuary at Trenton, NJ, and farther downstream from the Schuylkill River and other tributaries of the Delaware. In March, April, and May, when fresh-water flow is high, the average concentration of dissolved solids in the water at Bristol was 76 ppm (parts per million), and at Marcus Hook 112 PPM In August and September, streamflow is lower, and the average concentration of dissolved solids increased to 117 PPM at Bristol and 804 PPM at Marcus Hook. Major salinity invasions of the Delaware River occurred in 1949, 1953, 1954, 1957, and 1963. In each of these years the fresh-water flow into the tidal river at Trenton was low during the period from July to October. The greatest dissolved-solids concentrations in these monthly samples were 160 PPM at Bristol and 4,000 PPM at Marcus Hook. At times the dissolved-oxygen concentration of the river water has become dangerously low, especially in that reach of the river between Wharton Street and League Island. At the Benjamin Franklin Bridge, one-third of the samples of river water were less than 30 percent saturated with oxygen; however, no trend, either for better or for worse, was apparent during the 14-year period. It is useful now to summarize these monthly analyses for the period 1949-63 even though a much more detailed description of water quality in this reach of the estuary will soon become available through the use of recording instrumental conditions. This compendium of water-quality data is useful as an explicit statement of water quality during the 14-year study period and is valuable for directing attention to water-quality problems for selecting instrument sites, and for making comparative studies with the more detailed information which is already being obtained with the aid of recording instruments.

Water Supply Paper↗
USGS1965

Water-supply potential from an asphalt-lined catchment near Holualoa Kona, Hawaii

The Jenkins-Whitesburg area includes approximately 250 square miles In Letcher and Pike Counties in the southeastern part of the Eastern Coal Field. In this area ground water is the principal source of water for nearly all rural families, most public supplies, several coal mines and coal processing plants, and one bottling plant. The major aquifers in the Jenkins-Whitesburg area are the Breathitt and Lee Formations of Pennsylvanian age. Other aquifers range in age from Devonian to Quaternary but are not important in this area because they occur at great depth or yield little or no water. The Breathitt Formation occurs throughout the area except along the crest and slopes of Pine Mountain and where it is covered by unconsolidated material of Quaternary age. The Breathitt Formation consists of shale, sandstone, and lesser amounts of coal and associated underclay. The yield of wells penetrating the Breathitt Formation ranges from less than 1 to 330 gallons per minute. Well yield is controlled by the type and depth of well, character of the aquifer, and topography of the well site. Generally, deep wells drilled in valleys of perennial streams offer the best potential for high yields. Although enough water for a minimum domestic supply (more than 100 gallons per day) may be obtained from shale, all high-yielding wells probably obtain water from vertical joints and from bedding planes which are best developed in sandstone. About 13 percent of the wells inventoried in the Breathitt Formation failed to supply enough water for a minimum domestic supply. Most of these are shallow dug wells or drilled wells on hillsides or hilltops. Abandoned coal mines are utilized as large infiltration galleries and furnish part of the water for several public supplies. The chemical quality of water from the Breathitt Formation varies considerably from place to place, but the water generally is acceptable for most domestic and industrial uses. Most water is a calcium magnesium bicarbonate or sodium bicarbonate type, and nearly all sampled water contained enough iron to stain cooking and laundry utensils. The water ranged from soft to very hard, and only one well in the Breathitt Formation produced salty water. The absence of salty water may be due to abundant fractures which are associated with the Pine Mountain fault and which have allowed fresh water to enter the formation. The Lee Formation underlies the Cumberland Mountain section and is exposed along the crest and southeast slope of Pine Mountain. The Lee Formation consists of massive sandstone and conglomerate with thin beds of shale and a few thin coal seams. Although the Lee Formation is tapped by only a few wells in this area, it is potentially an important aquifer. Wells penetrating the Lee Formation in the Cumberland Mountain section would probably yield water under artesian pressure. Unlike most water from the Lee Formation in other part.3 of eastern Kentucky, all water from the Lee Formation in the Jenkins-Whitesburg area is fresh. All water from the Lee Formation contained more than 0.3 parts per million of iron and ranged from soft to moderately hard.

Water Supply Paper↗
USGS1965

Suitability of irrigation water and changes in ground-water quality in the Lompoc subarea of the Santa Ynez River Basin, Santa Barbara County, California

Analyses of water samples collected since 1934 from some of the irrigation wells in the Lompoc subarea of the Santa Ynes River valley have shown a gradual deterioration in the chemical quality of the water. Most of the ground water pumped in the subarea has a dissolved-solids contents ranging from about 700 to about 2,000 parts per million, of which sulfate and chloride are the predominant constituents. Suitability of the water for irrigation is variable and is dependent principally on "potential salinity" of the water, soil permeability, and type of crop. Changes in water quality are not consistent throughout the subarea. No doubt the chloride concentration increases as a result of both the recycling irrigation water and inflow of high-chloride low-sulfate connate water from the consolidated Tertiary rocks. The influence of recycled irrigation water is indicated by increase concentrations of chloride and sulfate in a ratio of 1:2. Inflow of high-chloride low-sulfate connate water is indicated by increased chloride concentration correlated with little or no change in sulfate concentration. Peak chloride concentrations in three local areas are probably the result of the inflow of connate water. Furthermore, ground-water gradients in each of the local areas are favorable for inflow from the consolidated rocks.

Water Supply Paper↗
USGS1966

Reconnaissance of the geology and ground-water resources in the Aurora area, St. Louis county, Minnesota

The Aurora area is a glaciated upland of drift-mantled slopes, channels, swamps, and glacial-lake plains. It covers about 24 square miles of the eastern part of the Mesabi Iron Range in northeastern Minnesota. A deep narrow channel along the Embarrass River, the principal outlet of a former large glacial lake north of the Embarrass Mountains, lies partly within the area. The deposits in the report area consist of bedrock and unconsolidated glacial drift. The 'bedrock belongs to the Animikie Group of late Preeambrian age and consists of taconite (an iron-rich silicate rock) in the northern part and slightly metamorphosed argillite in the middle and southern parts. Bedrock is exposed only in the open-pit iron mines. Large quantities of ground water are pumped from porous and permeable ore zones in the St. James Mine. Small quantities of ground water are obtainable from openings along bedding planes and fractures in the argillite. Unconsolidated deposits consisting of till and water-laid glacial and alluvial materials mantle the bedrock to depths ranging from about 20 feet in the north-central part of the Aurora area to more than 300 feet near the Embarrass River. Thick deposits of sand and gravel in the Embarrass channel are capable of yielding large quantites of water. At places along the Partridge River glaeiofluvial deposits (glacial sediments deposited in running water) could yield moderate to large quantities of water. Sandy to bouldery till yields small quantities of water to domestic wells. Well yields in the Aurora area range from less than 5 gpm (gallons per minute) to about 250 gpm from a well tapping an ore body. The specific capacity of wells penetrating ore zones ranges from about 7 gpm per foot of drawdown to 25 gpm per foot of drawdown. Although no attempt has been made to develop a high-yield well in the sand and gravel deposits of the Embarrass channel, more than 5,000 gpm is pumped from sumps which collect water from these deposits in the Embarrass mine. Most domestic wells yield about 5 gpm and are drilled and finished in sand or gravel in either the bouldery till or glaciofluvial deposits. Ground water from the unconsolidated deposits is hard and commonly contains large, undesirable amounts of iron and manganese. Water from the 'bedrock aquifers contains less iron and manganese than does water from the unconsolidated deposits.

Minnesota↗
USGS1965

Summary of floods in the United States during 1961

This report describes the most outstanding floods in the United States during 1961. The most damaging floods during the year were those caused by snowmelt in March and April in the upper Mississippi River basin and those accompanying Hurricane Carla in September. Hurricane Carla traveled northward along the east edge of Texas and then northeastward through southeastern Oklahoma, northwestern Arkansas, southeastern Missouri, and central Illinois. Heavy rains and floods occurred east of the hurricane's path in Texas and west of its path for the remainder of its journey. Mississippi, Alabama, and Georgia had moderate to severe floods in February and March from a series of large-area rainstorms. Many maximum peak discharges occurred, and streams remained at high stages for periods longer than any known before. Property damage was high and four lives were lost. Extensive flooding took place in May from southeastern Kansas and northeastern Oklahoma through northern Arkansas, southern Missouri, northern Kentucky, and the southern parts of Illinois, Indiana, and Ohio. Maximum discharges occurred at many sites throughout the area. Heavy flooding was experienced on Kootenai River at Bonners Ferry, Idaho, in May and June. These floods were noteworthy for their duration. The most tragic flood of the year was in July in Charleston, W. Va. A small area cloudburst flood caused 22 deaths and damage of more than \$1 million. Severe flooding occurred in December in the Tombigbee River, Pearl River, and Pascagoula River basins in Mississippi, Louisiana, and Alabama. Much damage resulted, and from two to three thousand persons were evacuated from large flooded areas. In addition to the floods mentioned above, 19 others of lesser magnitude are considered important enough to be included in this annual summary.

Water Supply Paper↗
USGS1965

Hydrology of the Little Plover River basin, Portage County, Wisconsin, and the effects of water resource development

The Little Plover River basin is in the sand-plain area of central Wisconsin. The basin and the surrounding sand-plain area provide a good fish and wildlife habitat and is a popular locale for sport fishing. Good yields may be obtained in the area from irrigated crops, and the irrigated acreage has been increasing rapidly in recent years. Sportsmen and conservationists are concerned about the effects of increased development of the water resources on the streams as trout habitat. In the past, many political and legal conflicts among water users have arisen from erroneous opinions as to the behavior of water. Many of these conflicts would be diminished or eliminated if the participants were cognizant of fundamental hydrologic principles. This study was made to demonstrate the extent and nature of the interrelation of ground water and surface water and the fundamental hydrologic principles governing water movement. The study was also made to determine the hydrologic changes that might occur following development, to provide information that might be used as a basis for planning water development, and for drafting legislation that recognizes the relation between ground water and surface water. Water has been developed in the Little Plover River basin for industry, for domestic and stock supplies, and for irrigation. Irrigated acreage is increasing in the area, and the use of water for irrigation may alter the hydrology of the basin somewhat. About 4,000-4,500 acres of land within the basin, or 50-60 percent of the basin area, is suitable for irrigated farming, but probably no more than 2,500 acres will be under irrigation in any one year, unless present crop-rotation practices are changed. Most of the Little Plover River basin is underlain by from 40 to 100 feet of glacial outwash consisting of highly permeable sand and gravel. The glacial outwash is the main aquifer in the area and is capable of yielding large quantities of water to wells. An aquifer test in the area indicated that the coefficient of transmissibility of the glacial outwash is about 140,000 gallons per day per foot. The specific yield of the outwash is about 20 percent, as determined from water-level and streamfiow data. Morainal deposits occur locally with the glacial outwash. These deposits transmit water readily and do not form barriers to ground water in the outwash. Relatively impermeable crystalline rocks underlie the glacial deposits, and a sandstone ridge of low permeability impedes the movement of ground water from the basin by underflow. The glacial outwash and morainal deposits are recharged by infiltration of 9-10 inches of the 31 inches of precipitation that falls on the area in an average year. If it is not withdrawn by wells for consumptive use or by phreatophytes, water that infiltrates the sand and gravel discharges later into the Little Plover River. This ground-water discharge constitutes 90-95 percent of the total flow of the Little Plover River. Annual evapotranspiration varies considerably, but generally ranges from 2 to 8 inches less than the potential evapotranspiration of 24 inches. Consumptive use of irrigation water averages about 4 inches per year. Most of the water pumped from wells otherwise would be discharged to the stream, and consumptive use of irrigation water will deplete streamflow by the amount of evapotranspiration. Pumping wells have little effect on the water level in the highly permeable sand and gravel. Significant interference between wells would occur only if large capacity wells were within a few tens of feet of each other. Ground water and surface water are closely interrelated in the sand-plain area and ground-water withdrawals near the Little Plover River may cause a measurable streamflow depletion. In a test, a well that was pumping about 1,120 gpm (gallons per minute) and that was 300 feet from the stream derived about 30 percent of its flow from the stream after 3 days of pumping. For this study, the effects of increased ground-water development were evaluated from a hypothetical development schedule, for which it was assumed that 500 acres were irrigated the first year and that an additional 50 acres were irrigated in each succeeding year for 10 years. It also was assumed that the average annual consumptive-use requirement for irrigation water would be one- third of an acre-foot per acre. Calculations indicate that the maximum monthly rate of depletion due to the consumptive use of 4 inches of ground water per year on 500 acres would be about 0.4 cfs (cubic feet per second) the first year and 0.5 cfs after 10 years of pumping. Other computations indicate that the maximum monthly rate of depletion due to irrigating 500 acres the first year and 50 additional acres each year for 10 years would be about 0.8 cfs. Maximum depletion would occur during the summer months, concurrent with the irrigation withdrawals. Because of the close interrelation between ground and surface water, surface- water withdrawals will cause an increased inflow of ground water to the stream and a decline in ground-water levels near the stream. These effects were demonstrated by pumping from the stream. After 29 hours of pumping, a depletion of 1,120 gpm at a site 7,000 feet downstream was about 200 gpm less than the diversion at the pump. Most of the 200 gpm was supplied from the stream-banks, and ground-water levels near the stream declined as much as 0.3 foot. Computations indicated that ground-water inflow, following a streamflow diver- sion that lowered the stage 0.15 foot, would be 0.14 cfs after 5 days and 0.06 cfs after 30 days. The demonstration of the quantitative relation between ground water and surface water, as given by this study, should provide a sound basis for planning water development to minimize conflicts of interest. The demonstrations also should provide a basis for drafting legislation that recognizes the interrelation of ground water and surface water. Because the geology and the hydrology are relatively uniform throughout the sand plains, many of the methods and hydrologic values determined for this detailed study of the Little Plover River basin may be applied to other basins in the sand-plain area.

Wisconsin↗
USGS1964

Public water supplies of the 100 largest cities of the United States, 1962

The public water supplies of the 100 largest cities in the United States (1960 U.S. Census) serve 9,650 million gallons of water per day (mgd) to 60 million people, which is 34 percent of the Nation's total population and 48 percent of the Nation's urban population. The amount of water used to satisfy the domestic needs as well as the needs of commerce and industry ranges from 13 mgd, which serves a population of 124,000, to 1,200 mgd, which serves a city of 8 million people. The water for the public supplies of these largest cities comes fro^n ground water wells and infiltration galleries and from surface water streams, reservoirs, and lakes. Twenty of the cities use ground water exclusively for public supplies, and 14 use a combination of ground and surface waters. Sixty-six cities use surface water solely; of these cities 37 depend solely upon reservoir water, and 20 depend solely upon natural streamflow. Water from the Great Lakes furnishes part or all of the water supply for 10 of these largest cities. Hardness of water, measured in parts per million (ppm), is an important factor in the usability of water supplies. Twenty-seven cities, serving a population of 8 million, have a raw-water hardness exceeding 180 ppm ("very hard"), but only 13 cities, serving a population of 3.7 million, have a "very hard" treated-water supply; and although 22 cities, serving about 10 million people, have a raw-water hardness ranging from 121 to 180 ppm ("hard"), only 16 cities, serving a population of 11 million, have a "hard" treated-water supply. Only 16 cities, serving a population of 16 million people, have a raw-water hardness ranging from 61 to 120 ppm ("moderately hard"), whereas 41 cities, serving a population of 22 million, have a treated-water supply having a hardness within this desirable range. A few cities that have a "soft" raw water add lime to control corrosion and consequently increase their water hardness to more than 61 ppm. Thirty cities, serving a population of about 23 million, have a treated-water supply with a hardness of less than 61 ppm. The dissolved-solids content in raw-water supplies of 27 cities, which serve a total population of slightly more than 21 million people, is 100 ppr^ or less. Thirty-eight cities serving a total population of 23 million people have raw-water supplies with a dissolved-solids content between 101 and 250 ppm, whereas 48 cities, serving a population of 28 million about half the population of these 1 2 PUBLIC WATER SUPPLIES, 1962 cities furnish water having this range of dissolved solids. Twentv-nine cities serving a total population of 11 million people have raw-water supplies that contain between 251 to 500 ppm of dissolved solids. Because some o* these cities treat their water supply, 22 cities serving 8 million people furnish water having a dissolved-solids content between 251 and 500 ppm. Only six cities, serving a population of about iy2 million people, have raw-water supplies containing more than 500 ppm of dissolved solids; four of these cities soften the water and consequently reduce the dissolved-solids content. Thus, about 1 million people in three cities receive water containing more than 500 ppm of dissolved solids. Chemical analyses of treated-water supplies indicate that more than 90 percent of the supplies contain less than (a) 500 ppm of dissolved solids, (b) 100 ppm of sulfate, (c) 50 ppm each of calcium, sodium, and chloride, (d) 30 ppm of silica, (e) 20 ppm of magnesium, (f) 5 ppm each of potassium and nitrate, and (g) 1 ppm of fluoride. Spectrographic analyses, reported in micrograms per liter (/*g per 1), show that 87 percent of the treated-water supplies contain less than 500 /*g per 1 of aluminum and more than 90 percent of the supplies contain less than (a) 500 /*g per 1 of strontium, (b) 150 /*g per 1 of iron, (c) 50 ^g per 1 of lithium, (d) 10 /ug per 1 each of molybdenum, nickel, lead, and vanadium, and (e) 5 /*g per 1 each cf chromium, rubidium, and titanium. Radiochemical analyses of treated-water supplies reveal that the maximum beta activity of these supplies is 130 picocuries per liter (pc per 1) and the maximum activity due to radium content is 2.5 pe per 1, both of which are well under the recommended maximum limits for drinking water. The report is divided into two sections. The first describes the uses of water in large cities, the raw-water supplies available for public supplies, tl-<; major and minor constituents and the properties of water, the methods of analyses, the treatment of water, the effects of chemical treatment on constituents and properties of water, and the costs of water treatment. The second is a city-by-city inventory that gives (a) the population of the city, (b) the adjacent communities supplied by the city water system, (c) the total population served, (d) the sources of water supply (including auxiliary and emergency supplies), (e) the average amount of water used daily, (f) the lowest 30-day mean discharge of streams used for public supply during recent years, (g) the treatment of water, (h) the rated capacity of each water-treatment plant, and (i) the storage capacity for raw and finished water. For 58 of the cities, the sources of water, the location of water-treatment plants, and the areas served by the city system are shown on maps. Chemical, spectrographic, and radiochemical analyses of treated water and chemical and spectrographic analyses for many of the raw-water supplies are presented in tabular form.

Water Supply Paper↗
USGS1966

Water in the Humboldt River Valley near Winnemucca, Nevada

Most of the work of the interagency Humboldt River Research Project in the Winnemucca reach of the Humboldt River valley has been completed. More than a dozen State and Federal agencies and several private organizations and individuals participated in the study. The major objective of the project, which began in 1959, is to evaluate the water resources of the entire Humboldt River basin. However, because of the large size of the basin, most of the work during the first 5 years of the project was done in the Winnemucca area. The purpose of this report is to summarize briefly and simply the information regarding the water resources of the Winnemucca area-especially the quantitative aspects of the flow system-given in previous reports of the project. The Winnemucca reach of the Humboldt River valley, which is in north-central Nevada, is about 200 miles downstream from the headwaters of the Humboldt River and includes that part of the valley between the Comus and Rose Creek gaging stations. Average annual inflow to the storage area (the valley lowlands) in the Winnemucca reach in water years 1949-62 was about 250,000 acre-feet. Of this amount, about 68 percent was Humboldt River streamflow, as measured at the Comus gaging station, 23 percent was precipitation directly on the storage area, 6 percent was ground-water inflow, and about 3 percent was tributary streamflow. Average annual streamflow at the Rose Creek gaging station during the same period was about 155,000 acre-feet, or about 17,000 acre-feet less than that at the Comus gaging station. Nearly all the streamflow lost was consumed by evapotranspiration in the project area. Total average annual evapotranspiration loss during the period was about 115,000 acre-feet, or about 42 percent of the total average annual outflow. The most abundant ions in the ground and surface water in the area are commonly sodium and bicarbonate. Much of the water has a dissolved-solids content that ranges from 500 to 750 parts per million; however, locally, the dissolved-solids content of the ground water is more than 5,000 parts per million. The chemical quality of the Humboldt River, especially during periods of low flow, reflects the chemical quality of ground-water inflow from tributary areas that discharges into the river. Almost all water in the project area is moderately hard to very hard; otherwise, it is generally suitable for most uses. Increased ground-water development, the conjunctive use of ground and surface water, and increased irrigation efficiency would probably conserve much of the water presently consumed by nonbeneficial evapotranspiration. Intensive ground-water development, especially from the highly permeable medial gravel subunit, will, however, decrease the flow of the Humboldt River to the extent that some pumpage may not be offset by a corresponding decrease in natural evapotranspiration losses. Such streamflow depletions will therefore infringe upon downstream surface-water rights. The results of this study indicate that the Humboldt River and ground water in the unconsolidated deposits beneath and adjacent to the river in the Winnemucca area are closely related. Somewhat similar conditions probably exist elsewhere in the Humboldt River valley. Additional detailed studies are needed-both upstream and downstream from the Winnemucca area-to adequately define the flow system and the interrelations among the components of the system in the remainder of the valley. Before proceeding with additional detailed studies, however, a 1-year overall appraisal of the water resources of the basin should be considered. A major objective of this study would be to provide information that would help select the next subarea of the valley to be studied in detail and to decide which of the methods of study used in the Winnemucca area could be most effectively used in the future studies.

Water Supply Paper↗
USGS1965

Identification and measurement of chlorinated organic pesticides in water by electron-capture gas chromatography

Pesticides, in minute quantities, may affect the regimen of streams, and because they may concentrate in sediments, aquatic organisms, and edible aquatic foods, their detection and their measurement in the parts-per-trillion range are considered essential. In 1964 the U.S. Geological Survey at Menlo Park, Calif., began research on methods for monitoring pesticides in water. Two systems were selected--electron-capture gas chromatography and microcoulometric-titration gas chromatography. Studies on these systems are now in progress. This report provides current information on the development and application of an electron-capture gas chromatographic procedure. This method is a convenient and extremely sensitive procedure for the detection and measurement of organic pesticides having high electron affinities, notably the chlorinated organic pesticides. The electron-affinity detector is extremely sensitive to these substances but it is not as sensitive to many other compounds. By this method, the chlorinated organic pesticide may be determined on a sample of convenient size in concentrations as low as the parts-per-trillion range. To insure greater accuracy in the identifications, the pesticides reported were separated and identified by their retention times on two different types of gas chromatographic columns.

Water Supply Paper↗
USGS1967

Determination of phenoxy acid herbicides in water by electron-capture and microcoulometric gas chromatography

A sensitive gas chromatographic method using microcoulometric titration and electron-capture detection for the analysis of 2,4-D, silvex, 2,4,5-T, and other phenoxy acid herbicides in water is described. The herbicides are extracted from unfiltered water samples (800-1,000 ml) by use of ethyl ether ; then the herbicides are concentrated and esterilied. To allow the analyst a choice, two esterilication procedures--using either boron trifluoride-methanol or diazomethane--are evaluated. Microcoulometric gas chromatography is specific for the detection of halogenated compounds such as the phenoxy acid herbicides whereas it does not respond to nonhalogenated components. Microcoulometric gas chromatography requires care and patience. It is not convenient for rapid screening of l-liter samples that contain less than 1 microgram of the herbicide. Although electroncapture gas chromatography is less selective and more critically affected by interfering substances, it is, nevertheless, convenient and more sensitive than microcoulometric gas chromatography. Two different liquid phases are used in the gas chromatographic columns--DC-200 silicone in one column and QF-1 silicone in the other. The performance of both columns is improved by the addition of Carbowax 20M. The Gas Chrom Q support is coated with the liquid phases by the 'frontal-analysis' technique. The practical lower limits for measurement of the phenoxy acid herbicides in water primarily depend upon the sample size, interferences present, anal instrumentation used. With l-liter samples of water, the practical lower limits of measurement are 10 ppt (parts per trillion) for 2,4-D and 2 ppt for silvex and 2,4,5-T when electron-capture detection is used, and approximately 20 ppt for each herbicide when analyzed by microcoulometric-titration gas chromatography. Recoveries of the herbicides immediately after addition to unfiltered water samples averaged 92 percent for 2,4-D, 90 percent for silvex, and 98 percent for 2,4,5-T. Studies on the stability of herbicides added to water samples showed that 2,4-D may be rapidly degraded, especially if the samples are obtained from areas which have been repeatedly sprayed with 2,4-D. When degradation was observed, added 2,4-D rapidly decomposed within 10 days. At concentrations of about 200 ppt, however, the degradation rate was diminished. In 20 days the concentration of 2,4-D was reduced to 160-180 ppt.

Water Supply Paper↗
USGS1976

Organic carbon and nitrogen concentrations and annual organic carbon load of six selected rivers of the United States

The organic carbon load during 1969-70 of each of the six rivers in this study is substantial. The 3.4-billion-kilogram (3.7-million-ton) and 47-million-kilogram (52-thousandton) annual organic carbon loads of the Mississippi River and the Brazos River (Tex.), respectively, were approximately equally distributed between dissolved and suspended phases, whereas the 725-million-kilogram (79.8-million-ton) organic load of the Missouri River was primarily in the suspended phase. The major portion of the 6.4-million-kilogram (7.3 thousand-ton) and the 19-million-kilogram (21-thousand-ton) organic carbon loads of the Sopchoppy River (Fla.) and the Neuse River (N.C.), respectively, was in the dissolved phase. DOC (dissolved organic carbon) concentrations in most rivers were usually less than 8 milligrams per litre. SOC (suspended organic carbon) concentrations fluctuated markedly with discharge, ranging between 1 and 14 percent, by weight, in sediment of most rivers. DOC concentrations were found to be independent of discharge, whereas SOC and SIC (suspended inorganic carbon) concentrations were positively correlated with discharge. Seasonal fluctuations in DOC and SOC were exhibited by the Missouri, Neuse, Ohio, and Brazos Rivers, but both SOC and DOC concentrations were relatively constant throughout the year in the Mississippi and Sopchoppy Rivers. The carbon-nitrogen ratio in the sediment phase of all river waters averaged less than 8 1 as compared with 12:1 or greater for most soils. This high nitrogen content shows a nitrogen enrichment of the stream sediment over that in adjacent soils, which suggests that different decomposition and humification processes are operating in streams than in the soils. The abundance of organic material in the dissolved and suspended phase of all river waters in this study indicate a large capacity factor for various types of organic reactivity within all streams and the quantitative importance of organic constituents in relation to the water quality of rivers and streams.

Water Supply Paper↗