USGS Science⌕ Search

SEARCH · USGS Science

Results for “Water Supply Paper”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,207 records · Page 67Linked to original sources
USGS1973

Water resources and geology of Mount Rushmore National Memorial, South Dakota

Ground water suitable for public supply can be obtained from fractured metamorphic and igneous rooks at Mount Rushmore National Memorial, S. Dak. The memorial comprises three main drainage basins: Starling basin, Lafferty Gulch basin, and East Boundary basin. Ground water is most prevalent in Lafferty Gulch basin but Starling basin contributes the most surface water. The total water supply was obtained from springs until 1967 when increasing numbers of visitors required development of additional sources. As a result of this investigation, wells 3 and 4 were drilled in Lafferty Gulch basin and East Boundary basin. Well 3 is 200 feet deep in mica schist and granite. It produced 7.3 million gallons of water in 1968 and 7.7 million gallons of water in 1969, the total supply for the memorial. Well 4 is 500 feet deep, also in mica schist and granite. It is not used at the present time (1970) but will be used in the future when more water is needed. Water from both wells is potable, but the quality of water from well 3 is superior to that from well 4. Mica schist is the most abundant rock in the memorial. The more prominent hills and mountains, however, are in large, northerly striking granite sills, some of which are several hundred feet thick. Pegmatite sills and dikes are also numerous. The western boundary of the memorial is at the east edge of the Harney Peak Granite batholith. The dip of schistosity and bedding in schist adjacent to the batholith is about 30 ? E. but increases across the memorial to about 65 ? E. in the northeast corner. At some locations in the memorial, granite or pegmatite sills act as ground-water dams preventing the movement of ground water down gradient. A pegmatite or granite sill is probably the cause of the accumulation of water in the vicinity of well 3. The well flows when it is not being pumped. The occurrence of ground water is dependent upon the presence of joints and fractures in the schist and granite bedrock. The rocks themselves are relatively impermeable and would yield little or no water in their unaltered state. Mica schist that has been intruded by granite and (or) pegmatite is more fractured and yields more ground water in the memorial than mica schist alone. This condition may be due to jointing and to the greater fracturability of the intruded rocks in the vicinity of granitic intrusions. Ground water is also available from alluvium in major valleys such as Starling basin and the valleys of Grizzly Bear Creek and Battle Creek. Evapotranspiration is the greatest use-item in the water budget. An approximation of evapotranspiration based upon an average annual precipitation of 19 inches is 1,600 acre-feet, or 80 percent of the annual precipitation. Several locations in the memorial have potential as future, sources of ground-water supplies. The most promising areas are near spring 6 in the southeast corner and alluvium in the valleys of Battle and Grizzly Bear Creeks. Developed and potential water resources in the memorial probably are sufficient to meet demands beyond the year 2000.

South Dakota↗
USGS1969

Sediment transport by streams in the Walla Walla River basin, Washington and Oregon, July 1962 - June 1965

The Walla Walla River basin covers about 1,760 square miles in southeastern Washington and northeastern Oregon. From the 6,000-foot crest of the Blue Mountains on the east to the 340-foot altitude of Lake Wallula (Columbia River) on the west, the basin is drained by the Touchet River and Dry Creek, entirely within Washington, and by Mill Creek, North and South Forks Walla Walla River, and Pine Creek-Dry Creek, which all head in Oregon. The central lowland of the basin is bordered on the north by Eureka Flat, Touchet slope, and Skyrocket Hills, on the east by the Blue Mountains, and on the south by the Horse Heaven Hills. The basin is underlain by basalt of the Columbia River Group, which .is the only consolidated rock to crop out in the region. Various unconsolidated fluviatile, lacustrine, and eolian sediments cover the basalt. In the western part of the basin the basalt is overlain by lacustrine deposits of silt and sand which in places are mantled by varying thicknesses of loessal deposits. In the northern and central parts of the basin the loess is at least 100 feet thick. The mountainous eastern part of the basin is underlain at shallow depth by basalt which has a residual soil mantle weathered from the rock. The slopes of the mountains are characterized by alluvial fans and deeply cut stream valleys ,filled with alluvium of sand, gravel, and cobbles. Average annual precipitation in the basin ranges from less than 10 inches in the desert-like areas of the west to more than 45 inches in the timbered mountains of the east; 65 percent of the precipitation occurs from October through March. The average runoff from the basin is about 4.8 inches per year. Most of the runoff occurs during late winter and early spring. Exceptionally high runoff generally results from rainfall and rapid melting of snow on partially frozen ground. During the study period, July 1964-June 1965, average annual sediment yields in the basin ranged from 420 tons per square mile in the mountainous area to more than 4,000 tons per square mile in the extensively cultivated northern and central parts of the basin, which are drained by the Touchet River and Dry Creek. The Touchet River and Dry Creek transported approximately 80 percent of the total sediment load discharged from the Walla Walla River basin. The highest concentrations were contributed by the loessal deposits in the Dry Creek drainage. Two runoff events resulting from rain and snowmelt on partially frozen ground produced 76 percent of the suspended sediment discharged from the basin during the study period. The maximum concentration measured, 316,000 milligrams per liter, was recorded for Dry Creek at Lowden on December 23. 1964. Daily suspended-sediment concentrations for the Walla Walla River near Touchet exceeded 700 milligrams per liter about 10 percent of the time, and 14,000 milligrams per liter about 1 percent of the time. The discharge-weighted mean concentration for the 3-year period of study was 7,000 milligrams per liter. Silt predominates in the suspended sediment transported by all streams in the basin. On the average, sediment from streams draining the Blue Mountains was composed of 20 percent sand, 60 percent silt, and 20 percent clay ; for streams draining the Blue Mountains slope-Horse Heaven Hills area, the percentages are 9, 65, and 26, respectively ; and for those draining the Skyrocket Hills-Touchet slope, the percentages are 5, 75, and 20, respectively. The bedload in the mountain and upland streams was estimated to be about 5-12 percent as much as the suspended load. For the Walla Walla River and its tributaries in the lower basin area, the bedload was estimated to be only about 2-8 percent as much as the suspended load.

Oregon, Washington↗
USGS1967

Definition of stage-discharge relation in natural channels by step-backwater analysis

The step-backwater method was investigated as a technique for defining the upper part of stage-discharge relation in a natural channel. State-discharge relations at 28 sites were computed by using this technique and compared with corresponding stage-discharge relations defined by current-meter measurements. In general, the agreement is remarkably good, and the step-backwater method should prove useful at many sites where current-meter measurements are not obtained.

Water Supply Paper↗
USGS1966

Effect of vertical motion on current meters

The effect of vertical motion on the performance of current meters at various stream velocities was evaluated to determine whether accurate discharge measurements can be made from a bobbing boat. Three types of current meters--Ott, Price, and vane types--were tested under conditions simulating a bobbing boat. A known frequency and amplitude of vertical motion were imparted to the current meter, and the related effect on the measured stream velocity was determined. One test of the Price meter was made under actual conditions, using a boat and standard measuring gear. The results of the test under actual conditions verified those obtained by simulating the vertical movements of a boat. The tests show that for stream velocities below 2.5 feet per second the accuracy of all three meters is significantly affected when the meters are subjected to certain conditions of vertical motion that can occur during actual field operations. Both the rate of vertical motion and the frequency of vertical oscillation affect the registration of the meter. The results of these tests, presented in the form of graphs and tables, can be used as a guide to determine whether wind and stream flow are within an acceptable range for a reliable discharge measurement from a boat.

Water Supply Paper↗
USGS1968

Determination of discharge during pulsating flow

Pulsating flow in an open channel is a manifestation of unstable-flow conditions in which a series of translatory waves of perceptible magnitude develops and moves rapidly downstream. Pulsating flow is a matter of concern in the design and operation of steep-gradient channels. If it should occur at high stages in a channel designed for stable flow, the capacity of the channel may be inadequate at a discharge that is much smaller than that for which the channel was designed. If the overriding translatory wave carries an appreciable part of the total flow, conventional stream-gaging procedures cannot be used to determine the discharge; neither the conventional instrumentation nor conventional methodology is adequate. A method of determining the discharge during pulsating flow was tested in the Santa Anita Wash flood control channel in Arcadia, Calif., April 16, 1965. Observations of the dimensions and velocities of translatory waves were made during a period of controlled reservoir releases of about 100, 200, and 300 cfs (cubic feet per second). The method of computing discharge was based on (1) computation of the discharge in the overriding waves and (2) computation of the discharge in the shallow-depth, or overrun, part of the flow. Satisfactory results were obtained by this method. However, the procedure used-separating the flow into two components and then treating the shallow-depth component as though it were steady--has no theoretical basis. It is simply an expedient for use until laboratory investigation can provide a satisfactory analytical solution to the problem of computing discharge during pulsating flow. Sixteen months prior to the test in Santa Anita Wash, a robot camera had been designed .and programmed to obtain the data needed to compute discharge by the method described above. The photographic equipment had been installed in Haines Creek flood control channel in Los Angeles, Calif., but it had not been completely tested because of the infrequency of flow in that channel. Because the Santa Anita Wash tests afforded excellent data for analysis, further development of the photographic ,technique at Haines Creek was discontinued. Three methods for obtaining the data needed to compute discharge during pulsating flow are proposed. In two of the methods--the photographic method and the depth-recorder method--the dimensions and velocities of translatory waves are recorded, and discharge is then computed by the procedure developed in this report. The third method?the constant-rate-dye-dilution method--yields the discharge more directly. The discharge is computed from the dye-injection rate and the ratio of the concentration of dye in the injected solution to the concentration of dye in the water sampled at a site downstream. The three methods should be developed and tested in ,the Santa Anita Wash flood control channel under controlled conditions similar to those in the test of April 1965.

Water Supply Paper↗
USGS1971

Analysis of current-meter data at Columbia River gaging stations, Washington and Oregon

The U.S. Geological Survey developed equipment to measure stream velocity simultaneously with 10 current meters arranged in a vertical and to measure velocity closer to the streambed than attainable with conventional equipment. With the 10 current meters, synchronous velocities were recorded for a period of 66 minutes at 10 different depths in one vertical of one gaging-station cross section. In addition, with a current meter installed on a special bracket to allow measurements to 0.5 foot above streambed, data were obtained at two to four verticals in four gaging-station cross sections. The mean velocity determined for the 66-minute period of record was 3.30 fps (feet per second). The graphic record of velocity was analyzed on a minute-by-minute basis. It was noted that the shape of the vertical velocity curves (plot of horizontal flow velocities measured in a vertical) changed from one minute to the next, but the change seemed to be random. Velocities obtained at different depths in the, profile fluctuated significantly, with the 1-minute velocities obtained at 0.05 depth (5 percent of total depths measured from the surface at indicated vertical) showing the smallest range--0.66 fps--and those at 0.55 depth the largest range--l.22 fps. The standard deviation, expressed in feet per second, of the velocity at each point in the vertical tended to increase with depth--from 0.16 fps at 0.05 depth to a maximum of 0.24 fps at 0.75 depth. The standard deviation, expressed as a percentage of the mean velocity, ranged from about 4 percent near the surface to 11 percent at 0.95 depth. In spite of the fluctuation in mean velocity that occurred during the 66 minutes and observation period of 4 minutes yields a mean velocity that differs from the 66-minute mean by less than one-half of a percent. Determining the mean velocity by averaging the 10-point observations of the 66minute run proved to be as accurate as by plotting the vertical velocity curvy (from the averaged 10 points) and then integrating the depth-velocity profile. In comparing the velocity obtained by integrating the depth-velocity profile with the 10-point mean velocity for other field data, collected beyond that obtained during the 66-minute run, the difference ranged from -1.3 to +1.7 percent and averaged -0.2 percent. Extension of the curve below the 0.95 depth by use of a power function proved to be fairly accurate (when compared with actual measurements within this reach made with the special current-meter bracket). However, the extension did not improve significantly the accuracy of the integrated-curve mean velocity. Both the one- and two-point methods were found to agree with the 10-point velocity. In computing mean river velocity, values determined by the two-point method ranged from -1.4 to +1.6 percent when compared with the base integrated-curve mean river velocity. The one-point method yielded results that ranged from -1.9 to +4.4 percent and averaged 40.1 percent. In determining river flow by use of the midsection and mean-section methods, the mean-section method uniformly yields lower flows for the same dart.. The range in difference is from -0.2 percent to -1.6 percent, with an average difference of -0.6 percent.

Water Supply Paper↗
USGS1971

Techniques and equipment required for precise stream gaging in tide-affected fresh-water reaches of the Sacramento River, California

Current-meter measurements of high accuracy will be required for calibration of an acoustic flow-metering system proposed for installation in the Sacramento River at Chipps Island in California. This report presents an analysis of the problem of making continuous accurate current-meter measurements in this channel where the flow regime is changing constantly in response to tidal action. Gaging-system requirements are delineated, and a brief description is given of the several applicable techniques that have been developed by others. None of these techniques provides the accuracies required for the flowmeter calibration. A new system is described--one which has been assembled and tested in prototype and which will provide the matrix of data needed for accurate continuous current-meter measurements. Analysis of a large quantity of data on the velocity distribution in the channel of the Sacramento River at Chipps Island shows that adequate definition of the velocity can be made during the dominant flow periods--that is, at times other than slack-water periods--by use of current meters suspended at elevations 0.2 and 0.8 of the depth below the water surface. However, additional velocity surveys will be necessary to determine whether or not small systematic corrections need be applied during periods of rapidly changing flow. In the proposed system all gaged parameters, including velocities, depths, position in the stream, and related times, are monitored continuously as a boat moves across the river on the selected cross section. Data are recorded photographically and transferred later onto punchcards for computer processing. Computer programs have been written to permit computation of instantaneous discharges at any selected time interval throughout the period of the current meter measurement program. It is anticipated that current-meter traverses will be made at intervals of about one-half hour over periods of several days. Capability of performance for protracted periods was, consequently, one of the important elements in system design. Analysis of error sources in the proposed system indicates that errors in individual computed discharges can be kept smaller than 1.5 percent if the expected precision in all measured parameters is maintained.

Water Supply Paper↗
USGS1970

Floods of December 1966 in southwestern Utah

Severe floods occurred in parts of southwestern Utah on December 5-6, 1966, as a result of precipitation of about 1 inch to more than 12 inches during December 3-6. The flood on the Virgin River was the greatest since the first settlers arrived in 1860. The peak discharge of the Virgin River at Virgin, Utah, was 22,830 cubic feet per second on December 6; this exceeded the previous maximum discharge of 13,500 cubic feet per second on March 3, 1938, and September 17, 1961, and probably has a recurrence interval of 100 years. At eight other gage sites in the flood area, the peak discharge in December 1966 was the highest of record; the recurrence intervals of some of the peak discharges may be 100 years. The flood peaks were generally of short duration and most streams receded to near base flow within 24 hours. The dissolved-solids content was significantly lower in the Virgin River at Virgin than at St. George, about 25 miles downstream; the water was of the calcium sulfate type at both sites. Data for the Santa Clara River above Winsor Dam and the Santa Clara River near Santa Clara show a significant increase in dissolved solids between the two sites. The water above Winsor Dam was of the calcium bicarbonate type, and the water near Santa Clara was of the calcium bicarbonate sulfate type. The suspended-sediment discharge, during the period December 5-8, 1966, at Santa Clara River above Winsor Dam, near Santa Clara was about foyer times greater than all the suspended-sediment discharge during the preceding 3 years ; the suspended-sediment discharge of the Virgin River at Virgin was greater during the 4-day period than during any one of the preceding 3 years. Nearly all the flood damage in the area occurred in the Virgin River basin. According to the Soil Conservation Service, total damage in the Dixie Soil Conservation District in Washington County was about $835,000; 60 percent of the damage was caused by floodwater and 40 percent by deposited sediment.

Utah↗
USGS1969

Floods of April 28, 1966 in the northern part of Dallas, Texas

The floods of April 28, 1966, in the northern part of Dallas, Tex., caused heavy damage to a relatively small area. Flood damage was estimated at $2,500,000; and of this amount, $1,330,000 damage was along Bachman Branch, which has a drainage area of 12.3 square miles. At least seven persons died as a direct result of the floodwaters. The flood was caused by a 5-hour storm in the early hours of April 28. Antecedent rainfall had so saturated the area that the intense, but relatively low, total rainfall (less than a 50-year return period) caused historical floods to be exceeded at many points. A peak runoff rate of 3,160 cubic feet per second per square mile occurred on a 1.5 square-mile area within the watershed.

Water Supply Paper↗
USGS1971

Floods of December 1966 in the Kern-Kaweah area, Kern and Tulare Counties, California; with section on Geomorphic Effects in the Kern River Basin

Past records of peak flow ,and 3-day ,storm-runoff volume in the Kern, Tule, and Kaweah River basins in California were greatly exceeded by the floods of December 1966. Streams rose rapidly following precipitation of as much as 15 inches in a 24-hour period on December 5-6 during a strong inflow of warm moist Pacific air across central California. As heavy rain continued, extremely high peak discharges occurred at most gaging stations between 2300 hours December 5 and 1800 hours December 6. Snowmelt was not a major cause o the floods, although some snow that had accumulated during minor November and early December storms was melted. This snowmelt was offset by snowpack accumulation at high altitudes where little runoff occurred during the storm. This report covers the area of mast intense precipitation and runoff. Areas of central California to the north and west had severe floods, but these, in general, were not nearly as great as ,previous record floods. The terrain of the flood area described in the report ranges from ,the rolling foothills at the east edge of the flat Tulare Lake basin to the steep slopes of the Sierra Nevada where considerable area is above an altitude of 9,000 feet. This report includes discussions of the antecedent hydrology and the meteorology of the stone; a description of the floods, storage regulation, flood damage, comparison to previous floods, sedimentation, channel changes, and flood frequency; a summary of flood stages and discharges; and detailed information on stage, discharge, and reservoir contents for December 1966.

Water Supply Paper↗
USGS1971

Summary of floods in the United States during 1966

This report describes the outstanding floods in the United States during 1966. The four most destructive floods occurred during March-April in the Red River of the North basin in northwestern Minnesota, during April-May in northeastern Texas, in August, in east-central Nebraska, and in December, in the Southwestern United States. For the second consecutive year, there was severe flooding in the Red River of the North basin in Minnesota during ,the spring snowmelt period. Unseasonally warm temperature caused rapid melting of a heavy snow cover, with water equivalent ranging from 5 to 7 inches, which covered .the northern two-thirds of the basin. Peak discharges were maximum of record at three gaging sites having periods of record ranging from 20 to 30 years, ,and peak discharges exceeded 50-year floods at nine sites. Damage from the flood was estimated at $10 million. In the period April 22-29, from 20 to 26 inches of rain fell in parts of the Sabine River basin in northeastern Texas. and high rates of runoff occurred from the headwaters of the Sulphur River southward .to the Trinity River basin. Flood damage was estimated at $12 million, and at least 25 persons lost their lives. Severe floods occurred along the Loup River ,and its tributaries in east-central Nebraska on August 12-14. The .peak discharge at nearly all gaging stations in the flood area exceeded the previous maximum of record. The floods we re caused by heavy rains of from 13 to 17 inches in about 24 hours. The storm was the most widespread in the area since 1896 and may have exceeded the area of the 1896 storm. The floods were unusual because of the consistently high discharges throughout a large flood area. Flood damage was estimated at $11 million. In early December a storm moved eastward from the Pacific coast in southern California into Southwestern United States. Intense precipitation occurred around the mountain ranges of south-central California and in and extending from southeastern Nevada across the southwestern corner of Utah to the Grand Canyon and southward to the mountains of central Arizona. Discharges on many streams exceeded the previous maximums known, and the flood was particularly damaging because of the large area involved. In .addition to these four floods, 19 others of lesser magnitude are considered important enough to be included in this annual summary.

Water Supply Paper↗
USGS1969

Hydrogeology of the Scioto River Valley near Piketon, south-central Ohio

A systematic study was made of one of Ohio's principal aquifers, a sand and gravel outwash in the Scioto River Valley, to determine the feasibility of developing a ground-water supply of 20 million gallons per day at a site near Piketon. The first part of the study was spent in determining the thickness and physical properties of the sand and gravel aquifer and in drilling test wells to determine the best site for the supply wells. The second part of the investigation was an aquifer infiltration test to determine the hydraulic properties of the aquifer and the conditions of stream recharge. A well 83 feet deep was drilled on the flood plain and was pumped for 9 days at the rate of 1,000 gallons per minute. Tile effect on the hydrologic system during and after the pumping was determined by measuring the water levels in an array of deep and shallow observation wells and in 8 drive-point wells installed in the bed of the river. Seldom have more comprehensive data been collected showing the effects of pumping on a natural, unconfined, hydrologic system. From these data were calculated the coefficient of transmissibility (215,000 gallons per day per foot) and the rate of streambed infiltration (0.235 million gallons per day per acre per foot). The aquifer was tested near the end of a long drought; so the ground-water levels and the river stage were very nearly following a level trend. Because the ground-water levels were essentially unaffected by extraneous influences, the test data are probably as precise and uncomplicated as is practical to obtain in the field. These data proved to be valid for use as design criteria for the location, spacing, and construction of four supply wells. The third part of the investigation was the testing and quantitative evaluation of the four supply wells before they were put into service. The wells were found to perform about as predicted, indicating that the hydraulic properties of the aquifer, as determined by standard methods, are fairly representative.

Ohio↗
USGS1969

Factors initiating phytoplankton blooms and resulting effects on dissolved oxygen in Duwamish River estuary, Seattle, Washington

Phytoplankton productivity, standing stock, and related environmental factors were studied during 1964-66 in the Duwamish River estuary, at Seattle, Wash., to ascertain the factors that affect phytoplankton growth in the estuary; a knowledge of these factors in turn permits the detection and evaluation of the influence that effluent nutrients have on phytoplankton production. The factors that control the concentration of dissolved oxygen were also evaluated because of the importance of dissolved oxygen to the salmonid populations that migrate through the estuary. Phytoplankton blooms, primarily of diatoms, occurred in the lower estuary during August 1965 and 1966. No bloom occurred during 1964, but the presence of oxygen-supersaturated surface water in August 1963 indicates that a bloom did occur then. Nutrients probably were not the primary factor controlling the timing of phytoplankton blooms. Ammonia ,and phosphate concentrations increased significantly downstream from the Municipality of Metropolitan Seattle's Renton Treatment Plant outfall after the plant began operation in June 1965, and concentrations of nitrogen and phosphorus were relatively high before operation of the Renton Treatment Plant and during nonbloom periods. The consistent coincidence of blooms with minimum fresh-water discharge and tidal exchange during August throughout the study period indicates that bloom timing probably was controlled mostly by hydrographic factors that determine retention time and stability of the surface-water layer. This control was demonstrated in part by a highly significant correlation of gross productivity with retention time (as indicated by fresh-water discharge) and vertical stability (as indicated by the difference between mean surface and mean bottom temperatures). The failure of a bloom to develop in 1964 is related to a minimum fresh-water discharge that was much greater than normal during that summer. Hydrographic factors are apparently important because, as shown by studies of other estuarine environments by other workers, phytoplankton production increases when the zone of vertical turbulent mixing is not markedly deeper than the compensation depth. Phytoplankton cells produced in the surface waters sink, thereby contributing oxidizable organic matter to the bottom saline-water wedge. The maximum BOD (biochemical oxygen demand) in this bottom wedge occurs in the same section of the estuary and ,at the same time as the maximum phytoplankton biomass (as indicated by chlorophyll a) and minimum DO (dissolved oxygen). Other sources of BOD occur in the estuary, and conditions of minimum discharge and tidal exchange assist in reducing DO. Nonetheless, the highly significant correlation of chlorophyll a with BOD throughout the summer indicates that respiration and decomposition of phytoplankton cells is dearly an important contributor of BOD. Increases in the biomass and resultant B0D of blooms because of increased effluent nutrients presumably would further decrease the concentration of DO. This possible effect of effluent nutrients was evaluated by laboratory .bioassays and by a comparison of mean annual biomasses in the estuary. A green algal population in vitro did increase in response to added effluent nutrients; however, the available field data suggest that a 46-percent increase in effluent discharge between 1965 and 1966 did not increase the estuary's phytoplankton biomass significantly.

Water Supply Paper↗
USGS1972

Physical, chemical, and biological aspects of the Duwamish River Estuary, King County, Washington, 1963-67

This report describes the significant results to 1967 of a comprehensive study that began in 1963 to evaluate what changes take place in an estuary as the loads .of raw and partially treated industrial and municipal wastes are replaced by effluent from a secondary treatment plant. The study area is the Duwamish River estuary, about 18.3 river kilometers long. At mean sea level the estuary has a water-surface area of about 1 square mile and a mean width of 440 feet. At the lowest and highest recorded tides, the volume of the estuary is about 205 and 592 million cubic feet, respectively. The estuary is well stratified (salt-wedge type) at fresh-water inflows greater than 1,000 cfs (cubic feet per second), but when inflow rates are less than 1,000 cfs the lower 5.6 kilometers of the estuary grades into the partly mixed type. The crosschannel salinity distribution is uniform for a given location and depth. Salinity migration is controlled by tides and fresh-water inflow. At fresh-water inflow rates greater than 1,000 cfs, water in the upper 8.4 kilometers of the estuary is always fresh regardless of tide. At inflow rates less than 600 cfs and tide heights greater than 10 feet; some salinity has been detected 16.1 kilometers above the mouth of the estuary. Studies using a fluorescent dye show that virtually no downward mixing into the salt wedge occurs; soluble pollutants introduced at the upper end of the estuary stay in the surface layer (5-15 ft thick). On the basis of dye studies when fresh-water inflow is less than 400 cfs, it is estimated that less than 10 percent of a pollutant will remain in the estuary a minimum of 7 days. Longitudinal dispersion coefficients for the surface layer have been determined to be on the order of 100-400 square feet per second. Four water-quality stations automatically monitor DO (dissolved oxygen), water temperature, pH, and specific conductance; at one station solar radiation also is measured. DO concentration in the surface layer decreases almost linearly in a downstream direction. Minimum DO concentration in the surface layer is usually greater than 4 rag/1 (milligrams per liter). The smallest DO values are consistently recorded in the bottom layer at the station 7.7 kilometers above the mouth; monthly means of less than 3 mg/1 of DO have occurred at this point. Manual sampling shows that the DO sag in the bottom layer oscillates between 7.7 and 10.4 kilometers above the mouth of the estuary. Multiple-regression analysis shows that the surface DO content can be estimated from the fresh-water inflow and water temperature. Tidal exchange and fresh-water inflow indirectly control the bottom DO content. Information available from previous studies failed to indicate a progressive decrease in DO content during the period 1949-56, but data from the present study suggest a slight general decrease in the annual minimum DO concentrations in both the upper and lower layers. Average nitrate concentration in fresh water at station 16.2 has increased progressively since 1964, by amounts greater than those which can be attributed to the Renton Treatment Plant, 4.3 kilometers upstream from station 16.2. The BOD (biochemical oxygen demand) in both surface and bottom layers is generally less than 4 rag/1 of oxygen, but values greater than 6 rag/1 have been measured during a period of phytoplankton bloom. Phytoplankton blooms can occur during periods of minimum tidal exchange and fresh-water inflows of less than 300 cfs if solar radiation and water temperature are optimum. Nutrients (nitrogen and phosphorus compounds) do not control the occurrence of a bloom, because sufficient quantities of these nutrients are always present. Nutrients in the treated effluent may increase the biomass of the bloom. Trace-element studies have not defined any role that these elements may play in algal growth. The inflowing fresh water contains principally calcium and bicarbonate and has a dissolved-solids content ra

Water Supply Paper↗
USGS1972

Measurement of salt-wedge excursion distance in the Duwamish River Estuary, Seattle, Washington, by means of the dissolved-oxygen gradient

The Duwamish River estuary has been the object of a series of comprehensive studies undertaken to predict the effects of the changing character of waste-water inputs on the water quality of the estuary. This report discusses the fresh- and salt-water relations of the estuary. The distance that the salt-water wedge in the estuary moves upstream and downstream with the tide is measured by a method that utilizes the persistence of the longitudinal gradient of dissolved oxygen in the salt water of the wedges. The method, though unorthodox, can serve as an independent check on any other measurements of tidal-excursion distance. Typical values obtained were a 1-kilometer excursion for a 1.3-meter tide range and a 3-kilometer excursion for a 3-meter tide range. This method of tracing the water movement seems to work because of two unusual aspects of the Duwamish River estuary: (1) the channel configuration is simple and well-suited to synoptic measurement and (2) the physical properties of the entering salt water are nearly constant.

Water Supply Paper↗