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USGS1968

Water resources of King County, Washington

Although the total supply of water in King County is large, water problems are inevitable because of the large and rapidly expanding population. The county contains a third of the 3 million people in Washington, most of the population being concentrated in the Seattle metropolitan area. King County includes parts of two major physiographic features: the western area is part of the Puget Sound Lowland, and the eastern area is part of the Cascade Range. In these two areas, the terrain, weather, and natural resources (including water) contrast markedly. Average annual precipitation in the county is about 80 inches, ranging from about 30 inches near Puget Sound to more than 150 inches in parts of the Cascades. Annual evapotranspiration is estimated to range from 15 to 24 inches. Average annual runoff ranges from about 15 inches in the lowlands to more than 100 inches in the mountains. Most of the streamflow is in the major basins of the county--the Green-Duwamish, Lake Washington, and Snoqualmie basins. The largest of these is the Snoqualmie River basin (693 square miles), where average annual runoff during the period 1931-60 was about 79 inches. During the same period, annual runoff in the Lake Washington basin ( 607 square miles) averaged about 32 inches, and in the Green-Duwamish River basin (483 square miles), about 46 inches. Seasonal runoff is generally characterized by several high-flow periods in the winter, medium flows in the spring, and sustained low flows in the summer and fall. When floods occur in the county they come almost exclusively between October and March. The threat of flood damage is greatest on the flood plaits of the larger rivers, but in the Green-Duwamish Valley the threat was greatly reduced with the completion of Howard A. Hanson Dam in 1962. In the Snoqualmie River basin, where no such dam exists, the potential damage from a major flood increases each year as additional land is developed in the Snoqualmie Valley. Only moderate amounts of sediment are transported by most streams in the county, except during short periods of heavy rain in the winter. The temperature and chemical quality of surface waters are well suited to the requirements of fisheries and for municipal, industrial, and domestic supplies. Little treatment is needed for most uses of surface water, except where the water is subject to pollution. Most recoverable ground water in the county occurs in the Puget Sound Lowland, where great volumes of unconsolidated sedimentary deposits were left by the continental glaciers of the Pleistocene Epoch. Bedrock, most of which is in the Cascade Range, contains very little ground water. Numerous springs, largely undeveloped, occur in several parts of the county. Most of the ground water is of good to excellent quality except for excessive iron, which in some places may require treatment of the water before it is suitable for domestic or industrial use. Excluding water used for hydroelectric-power, recreation, and fisheries, more than 80 percent of the water used in the county is provided by municipal-supply systems. Each of the major river basins includes municipal watersheds that provide large supplies of excellent water. By the 1980's, more than 90 percent of the county's population will probably be served by the Seattle municipal supply. With full development, Seattle's water system would have a capacity sufficient to supply more than 2 million people with 300 gallons per person per day. Most industrial and commercial establishments in the county obtain water from public supply systems. The most serious water problem in the county at present (1965) is the threat of pollution in the densely populated areas. The immediate threat in the Seattle area is being reduced by the sewage-treatment program of the Municipality of Metropolitan Seattle, which will eliminate the discharge of waste into Lake Washington. Expected increases in population and industry will introduce new problems that will require additional planning to assure adequate water quality for fisheries, recreation, and other uses.

Washington↗
USGS1968

Ground-water hydrology of the Sevier Desert, Utah

The Sevier Desert, as used in this report, comprises the main part of the Sevier Desert, the Tintic Valley, and the southeastern part of the Old River Bed. It covers an area of about 3,000 square miles and occupies a large basin in the eastern part of the Basin and Range physiographic province. Large alluvial fans extend from the mountain fronts into the basin where they interfinger with eolian and lacustrine deposits and with fluvial deposits of the Sevier River. These unconsolidated deposits form a multiaquifer artesian system that is more than 1,000 feet thick and that extends from near the area of main recharge along the east side of the basin to Sevier Lake. Most of the recharge to the ground-water reservoir results from water entering alluvial fans as percolation from streams, irrigation ditches, and irrigated fields. Another important source may be water in the limestone, quartzite, and other consolidated rocks in the mountains that border the basin. Leakage from the Central Utah Canal is a major source of recharge to the water-table aquifer. Flowing wells are common in the central lowland part of the Sevier Desert, but as a result of below-normal precipitation and an increase in withdrawals from wells during 1950-64, the area of flowing wells has decreased. The quantity of ground water being wasted from flowing wells is not more than a few hundred acre-feet a year. The amount of water discharged by withdrawal from wells has increased nearly 15 times since 1950 (from 2,000 acre-feet in 1950 to 30,000 acre-feet in 1964). As a result of this increasing withdrawal, the water levels in observation wells have declined 4 feet in areas of small withdrawals to more than 7 feet near centers of pumping for public supplies and irrigation. An estimated 135,000-175,000 acre-feet of ground water is consumed by evapotranspiration each year in the 440,000 acres of desert that mainly support phreatophytes. This rate of discharge has changed little since 1950. The consumptive waste of ground water by undesirable phreatophytes, principally saltcedar and pickleweed, was not a serious problem in 1964 but could become a serious problem in the near future if saltcedar is permitted to spread. Water levels in wells changed little during 1935-40. During 1941-50, however, water levels rose in response to the general above-normal precipitation during 1939-47. During 1950-64 water levels declined, partly in response to below-normal precipitation and partly in response to an increase in pumping from irrigation wells. Although the period 1961-63 was one of above-normal precipitation, water levels continued the overall decline that was started in 1950. The decline, therefore, probably is due to increased pumping. The amount of water that could be obtained from storage if the piezometric surface in the artesian aquifer were lowered 20 feet is estimated to be 120,006 acre-feet. The specific capacities of wells used for irrigation and public supply range from 5 to 215 gallons per minute per foot of drawdown. Specific capacities generally decrease with increasing distances away from the edge of the basin.

Utah↗
USGS1968

Water for the growing needs of Harrison County, Mississippi

The potential for water-supply development in Harrison County is almost unlimited. During an average year, more than 350 billion gallons of water flow into the Gulf of Mexico from the streams of the county. With storage reservoirs these streams have a potential sustained supply of hundreds of millions of. gallons per day. Recreation uses and flood-control benefits could also be considered in reservoir design. Upstream from the zones of salt-water penetration, mineral content is low and fairly constant. Water in the streams generally has high color and low pH ; treatment would be required for most municipal and industrial uses. Impoundment in reservoirs normally would have little effect on the quality of the surface water. However, impoundment would trap most of the suspended-sediment load of the streams. Flooding along the major streams of Harrison County is a minor hazard at present (1966), but with further industrial development and urbanization, flooding in these now rural areas could become serious. Intense rainfall from thunderstorms and hurricanes causes serious local flooding in the populous areas near the coast. Tidal flooding, a result of tropical storms, is an ever-present hazard in areas near the coast. The ground-water reservoir, which at present provides all fresh-water supplies, is capable of supporting many times the 25 million gallons per day withdrawal through existing wells. Fresh water occurs to depths as great as 2,500 feet in sand aquifers of Pliocene and Miocene age. Many of the aquifers have high transmissibility; most of those tested have transmissibility in the range, of 50,000-100,000 gallons per day per foot. Although few wells produce more than 1,000 gallons per minute, several of the aquifers can yield two to three times that amount to wells designed for the higher production. Artesian water levels along the coast are declining at a rate of 1 foot per year on the average; however, water levels are still above or only slightly below the land surface in most places, and considerable additional drawdown is economically available. Newly discovered deep aquifers (1,700-2,500 ft) have water levels 100 feet above the surface and probably will provide flow yields of 2,000 gallons per minute or more. The temperature of this deep water is nearly 100?F. Nearly all the ground water is of good quality and requires little or no treatment for most uses. It is soft, and total mineral content is usually less than 250 parts per million. Color is seldom a problem, although it may have to be considered in the undeveloped deep aquifers. The pH ordinarily is greater than 7.0, but it is slightly less than 7.0 in most places in the shallow aquifers.

Water Supply Paper↗
USGS1968

Water resources of Grant and Hot Spring Counties, Arkansas

In Grant and Hot Spring Counties the Ouachita, Saline, and Caddo Rivers yield large quantities of soft, good-quality water. Small streams in southeastern Hot Spring County and some of the small streams in the Ouachita Mountains have relatively high base flow; in Grant County small streams yield little water during dry periods. At times, sewage and mine drainage pollute the Ouachiba River from the Garland County line to a point a few miles below Lake Catherine. At low flow, Hurricane Creek water is unfit for most uses. The Sparta Sand, the principal aquifer, yields as much as 8.50 gpm of soft water in Grant County. The Carrizo Sand and Cane River Formation are potentially important aquifers in Grant County and southeastern Hot Spring County. The Wilcox Group yields as much as 300 gpm of fresh water in southeastern Hot Spring County and southwestern Grant County; in the rest of Grant County its water is brackish. The alluvium along .the principal streams and ,the consolidated rocks of the Ouachita Mountains yield small quantities of water that vary in quality from place to place. Some of .the water from the alluvium has high nitrate content and may be a hazard to health.

Water Supply Paper↗
USGS1968

Use of water by riparian vegetation, Cottonwood Wash, Arizona

The change in water use as a result of the modification of riparian vegetation was measured in Cottonwood Wash, Mohave County, Ariz. A 4.1-mile length of the stream channel was selected and divided into a 2.6-mile upper reach and a 1.5-mile lower reach. Measurements of streamflow, ground-water levels, vegetation, and meteorological phenomena in the area defined the use of water by riparian vegetation under natural hydrologic conditions. Subsequent defoliation and eradication of the vegetation in the lower reach permitted the determination of the change in water use as a result of the modification. The computed average loss of water from the lower reach before modification was 80 acre-feet per growing season, a quantity which represented about 18 percent of the average flow entering the reach in the same period. The average loss after modification of the vegetation was 42 acre-feet per growing season, a quantity which represented about 12 percent of the average flow entering the reach in the same period.

Arizona↗
USGS1968

Ground-water reconnaissance of the Santa Barbara-Montecito area, Santa Barbara County, California

This is the third interpretive report prepared by the U.S. Geological Survey in cooperation with the Santa Barbara County Water Agency on the groundwater resources of areas along the south coast of the county. The two previous reports--one by J. E. Upson in 1951 and another by R. E. Evenson, H. D. Wilson, Jr., and K. S. Muir--were on ground-water conditions in the Goleta and Carpinteria basins. The Santa Barbara-Montecito area is between those two basins-the Goleta basin on the west and the Carpinteria basin on the east. This area of about 30 square miles extends from the Pacific Ocean on the south to the Santa Inez Mountains on the north. The city of Santa Barbara and the towns of Montecito and Summerland are within the area. The Santa Barbara-Montecito area is a low-lying flat section of the coastal plain. Farther inland are highlands of consolidated rock and terrace deposits. The highlands are areas of uplift, folding, and faulting, and the lowlands are structural depressions. Most of the urban development in the area has been in the lowlands. The unconsolidated deposits that have partly filled the structural depressions make up the ground-water reservoir of the Santa Barbara-Montecito area. They include the Santa Barbara Formation of Pliocene and Pleistocene age, the Casitas Formation of Pleistocene age, and the alluvium of late Pleistocene and Recent age. These deposits underlie an area of about 20 square miles and have a maximum thickness of about 2,000 feet. The consolidated rocks of Tertiary age that underlie and form the boundaries of the ground-water reservoir contain ground water in fractures and in sandstone beds. However, the consolidated rocks are not an important source of ground water. In 1959, a year the ground-water basins were full and ground water in storage was at a maximum, storage in the Santa Barbara area was 184,000 acre-feet, and storage in the Montecito area was 97,000 acre-feet. By 1964, in response to below-average recharge and continued withdrawal by pumping, the quantity of ground water in storage in the Santa Barbara area had decreased to 178,000 acre-feet. Because of a reduction in pumpage, there was little change in storage in the Montecito area between 1959 and 1964. Deep percolation of rain, seepage from streams, and subsurface inflow from consolidated rocks are the main sources of recharge to the ground-water reservoir in the Santa Barbara-Montecito area. The most important discharge is by pumping.The long-term perennial yield of the ground-water reservoir of the Santa Barbara area is estimated to be 1,700-2,000 acre-feet. Present data are insufficient to accurately determine the perennial yield of the reservoir in the Montecito area, but it is estimated to be about 2,500 acre-feet. Most ground water in the Santa Barbara-Montecito area is suitable for general use. However, ground water in some of the consolidated rocks and in the shallow unconsolidated deposits adjacent to the coast is too saline for most uses. Seawater intrusion has occurred in the Santa Barbara area and the western part of the Montecito area. The intrusion, however, is limited to the upper part of the nearshore shallow alluvial deposits and contaminates only wells which were constructed without a near-surface seal.

California↗
USGS1968

Chemical quality of surface waters in Devils Lake basin North Dakota, 1952-60

Above-normal precipitation in 1954, 1956, and 1957 caused the water surface of Devils Lake to rise to an altitude of 1,419.3 feet, its highest in 40 years. Nearly all the water entering the lake flowed through Big Coulee, and about three-fourths of that inflow was at rates greater than 100 cubic feet per second. At these rates, the inflow contained less than 600 ppm (parts per million) dissolved solids and was of the calcium bicarbonate type. Because the inflow was more dilute than the lake water, the dissolved solids in the lake decreased from 8,680 ppm in 1952 to about 6,000 ppm in 1956 and 1957. Subsequently, however, they increased to slightly more than 8,000 ppm and averaged 6,800 ppm for the 1954-60 period. Sodium and sulfate were the principal dissolved constituents in the lake water. Although the concentration of dissolved solids varied significantly from time to time, the relative proportions of the chief constituents remained nearly the same. Water flowed from Devils Lake to Mission Bay in 1956,1957, and 1958, and some flowed from Mission Bay into East Bay. However, no water moved between East Devils Lake, western Stump Lake, and eastern Stump Lake during 1952-60; these lakes received only local runoff, and the variations in their water volume caused only minor variations in dissolved solids. For the periods sampled, concentrations averaged 60,700 ppm for East Devils Lake, 23,100 ppm for western Stump Lake, and 127,000 ppm for eastern Stump Lake. Sodium and sulfate were the chief dissolved constituents in all the lakes of the Devils Lake chain. Water in eastern Stump Lake was saturated with sodium sulfate and precipitated large quantities of granular, hydrated sodium sulfate crystals on the lakebed and shore in fall and winter. A discontinuous layer of consolidated sodium sulfate crystals formed a significant part of the bed throughout the year. Measured concentrations! of zinc, iron, manganese, fluoride, arsenic, boron, copper, and lead were not high enough to harm fish. Data on alpha and beta particle activities in Devils Lake were insufficient to determine if present activities are less than, equal to, or more than activities before nuclear tests began. Miscellaneous surface waters not in the Devils Lake chain contained dissolved solids that ranged from 239 to 61,200 ppm. The lakes that spill infrequently and have little or no ground-water inflow and outflow generally contain high concentrations of dissolved solids. Salt balance computations for Devils Lake for 1952-60 indicate that a net of as much as 89,000 tons of salts was removed from the bed by the water in some years and as much as 35,000 tons was added to the bed in other years. For the 9-year period, the tons removed exceeded the tons added; the net removed averaged 2.7 tons per acre per year. Pickup of these salts from the bed increased the dissolved solids in the lake water an average of 193 ppni per year. Between 1952 and 1960, 201,000 tons of salt was added to the bed of East Devils Lake, 15,100 tons to the bed of western Stump Lake, and 421,000 tons to the bed of eastern Stump Lake. Laboratory examination of shore and bed material indicated that the shore contained less weight of salt per unit weight of dry, inorganic material than the bed. Calcium and bicarbonate were the chief constituents dissolved from bed material of Devils Lake, whereas sodium and sulfate were the chief constituents dissolved from bed material of East Bay, East Devils Lake, and eastern and western Stump Lakes. Generally, calcium and bicarbonate were the chief constitutents dissolved from shore material of all these lakes. Evidence indicates that not more than 20 percent of the salt that "disappeared" from the water of Devils Lake west of State Route 20 as the lake altitudes decreased years ago will redissolve if the lake altitude is restored.

North Dakota↗
USGS1968

Analysis of water quality of the Mahoning River in Ohio

The Mahoning River drains the densely populated and industrialized Warren-Youngstown area in northeastern Ohio. Significant chemical constituents and physical properties generally regarded as important in establishing water-quality standards for the Mahoning River are evaluated on the basis of hydrologic conditions and water use. Most of the interpretations and the appraisal of water-quality conditions are based on data collected from January 1963 to December 1965. Generally, streamflow during this period was lower than during a selected long-term reference period ; however, extremely low flows that occurred in the reference period did not occur in the 3-year study period. Water temperatures of the Mahoning River at Pricetown and Leavittsburg were not affected by thermal loading. Water temperatures at those stations ranged from the freezing point to 78?F during the 1963-65 period. Downstream from Leavittsburg, the use of large quantities of water for industrial cooling caused critical thermal loading during periods of low streamflow. Maximum water temperatures were 108?F and 104?F at Struthers and Lowellville, respectively. Water temperatures of the Mahoning River were lower during high water discharges and increased with higher steel-production indices. Flow augmentation and modifications in industrial processes have improved the water-temperature conditions in recent years. A combination of oxygen-consuming materials and warmed water from industrial and municipal wastes discharged into the lower reaches of the Mahoning River frequently depleted the dissolved-oxygen content. At Lowellville, the river water had a dissolved-oxygen content of 5 ppm (parts per million) or less for 67 percent of the time and 3 ppm or less for 16 percent of the time during the study period. The percentage of saturation of dissolved oxygen followed a similar trend. Both the dissolved-oxygen concentration and the percentage of saturation were noticeably lower downstream from Leavittsburg during the warm months when water temperatures were high and streamflow was low. The dissolved-oxygen content in the Mahoning River at Leavittsburg and Pricetown was almost always at acceptable levels. The calculated dissolved-solids concentration of the Mahoning River ranged from 150 to 450 ppm at Leavittsburg and from 200 ppm to 650 ppm at Lowellville. Industrial use of the water caused an increase in the dissolved-solids concentration at Lowellville. During one steel-mill shutdown the average dissolved-solids concentration decreased from about 360 to about 280 ppm. Chloride concentrations in the Mahoning River ranged from 42 ppm at Pricetown to 108 ppm at Struthers. The chloride load at 50-percent flow duration was 9 and 69 tons per day at Pricetown and Lowellville, respectively. The chloride content of the Mahoning River was well within acceptable levels. Sulfate from wastes disposal and acid mine drainage made up the largest quantity of dissolved-solids load in the Mahoning River. The sulfate load at 50-percent flow duration increased from 38 tons per day at Pricetown to 300 tons per day at Lowellville. At Pricetown the sulfate load ranged from about 2 to 588 tons per day, while at Lowellville, downstream from the industrialized area, the range was from 106 to 2,420 tons per day. Comparison of sulfate loads during periods of steel production with periods of steel-mill shutdown indicated that during low flow about half the sulfate load at Lowellville was derived from steel-mill wastes when the production index was 100. The alkalinity load of the Mahoning River at 50-percent flow duration increased from Pricetown (23 tons per day) to Lowellville (41 tons per day). During steel production the alkalinity of the water showed a marked decrease from Leavittsburg downstream to Lowellville. However, during steel-mill shutdowns the chemical composition of the river at Youngstown and Lowellville was similar to that at Leavittsburg. Acid mine drainag

Water Supply Paper↗
USGS1968

Water-mineral relations of Quaternary deposits in the Lower Platte River drainage area in eastern Nebraska

The partial pressure of carbon dioxide (PCO2), the degree of saturation with respect to calcite (IAP/K calcite), the pH, and the concentrations of selected constituents in solution were determined for water from 52 wells and the Platte River. Compared to the PCO2 in the atmosphere, the average PCO2 in the ground water was many times greater and that in .the river water was about twice as great. The high PCO2 in the ground water probably results from the absorption, by infiltrating precipitation, of carbon dioxide produced in the soil by respiration of plant roots ,and microorganisms. The values for IAP/K calcite for the ground water ranged from 0.141 to 1.29 and for the river water the average was 9.6. Water from each of the 10 sampled wells on the terrace plain in southeastern Saunders County was unsaturated with respect to calcite, whereas water from seven of the 42 wells on the Platte River flood plain was nearly saturated or supersaturated. Of the ,seven, two were in the Lincoln city well field where hydrologic relations indicate that a large fraction of the water yielded by the wells is induced seepage from the .river. That more of the city wells did not yield supersaturated water is surprising in view of the high IAP/K calcite values for the river water. Supersaturation of water from five of nine sampled wells downvalley from the well field probably is due to the presence of numerous limestone fragments in the Quaternary deposits in that part of the area. also surprising was the finding that the average pH of the water from the city wells was 1 unit lower than that of the river water. The presence of both dissolved iron and dissolved oxygen in the water from several of the city wells probably reflects derivation of the water from two distinct sources : ground water naturally in the aquifer and induced seepage from the river.

Water Supply Paper↗
USGS1968

Hydrology of Crater, East and Davis Lakes, Oregon; with section on Chemistry of the Lakes

Crater, East, and Davis Lakes are small bodies of fresh water that occupy topographically closed basins in Holocene volcanic terrane. Because the annual water supply exceeds annual evaporation, water must be lost by seepage from each lake. The seepage rates vary widely both in volume and in percentage of the total water supply. Crater Lake loses about 89 cfs (cubic feet per second), equivalent to about 72 percent of its average annual supply. East Lake loses about 2.3 cfs, or about 44 percent of its estimated supply. Davis Lake seepage varies greatly with lake level, but the average loss is about 150 cfs, more than 90 percent of its total supply. The destination of the seepage loss is not definitely known for any of the lakes. An approximate water budget was computed for stationary level for each lake, by using estimates 'by the writer to supplement the hydrologic data available. The three lake waters are dilute. Crater Lake contains about 80 ppm, (parts per million) of dissolved solids---mostly silica, sodium, and bicarbonate, and lesser amounts of calcium, sulfate, and chloride. Much of the dissolved-solids content of Crater Lake---especially the sulfate and chloride---may be related to fumarole and thermal-spring activity that presumably followed the collapse of Mount Mazama. Although Grater Lake loses an estimated 7,000 tons of its 1.5million-ton salt content each year by leakage, the chemical character of the lake did not change appreciably between 1912 and 1964. East Lake contains 200 ppm of dissolved solids, which includes major proportions of calcium, sodium, bicarbonate, and sulfate, but almost no chloride. The lake apparently receives much of its dissolved solids from subsurface thermal springs. Annual solute loss from East Lake by leakage is about 450 tons, or 3 percent of the lake's 15,000-ton estimated solute content. Davis Lake contains only 48 ppm of dissolved solids, much of which is silica and bicarbonate; chloride is almost completely absent. Approximate physical and hydrologic data for the lakes are summarized in the following table. [Table]

Water Supply Paper↗
USGS1969

Geohydrology and water utilization in the Willcox Basin, Graham and Cochise Counties, Arizona

The Willcox basin is an area of interior drainage in the northern part of Sulphur Springs Valley, Cochise and Graham Counties, Ariz. The basin comprises about 1,500 square miles, of which the valley floor occupies about 950 square miles. The basin probably formed during middle and late Tertiary time, when the area was subjected to large-scale faulting accompanied by the uplift of the mountain ranges that presently border it. During and after faulting, large quantities of alluvium were deposited in the closed basin. The rocks in the basin are divided into two broad groups--the rocks of the mountain blocks, of Precambrian through Tertiary age, and the rocks of the basin, of Tertiary and Quaternary age. The mountain blocks consist of igneous, metamorphic, and sedimentary rocks; the water-bearing characteristics of these rocks depend primarily on their degree of weathering and fracturing. Even in areas where these rocks are fractured and jointed, only small amounts of water have been developed. The rocks of the basin consist of moderately consolidated alluvium, poorly consolidated alluvium, and unconsolidated alluvium. The water-bearing characteristics of the moderately and poorly consolidated alluvium are not well known. The unconsolidated alluvium underlies most of the valley floor and consists of two facies, stream deposits and lake beds associated with the old playa. The lenticular sand and gravel layers interbedded in silt- and clay-size material of the unconsolidated alluvium constitute the principal aquifer in the basin. The other aquifers, which yield less water, consist of beds of poorly to moderately consolidated sand- and gravel-size material; these beds occur in both the poorly consolidated and moderately consolidated alluvium. In the Stewart area the median specific capacity of wells per 100 feet of saturated unconsolidated alluvium was 20 gallons per minute, and in the Kansas Settlement area the specific capacity of wells penetrating the poorly and moderately consolidated alluvium, undifferentiated, was only 7.4 gallons per minute per 100 feet of saturated material penetrated. The aquifer in the Kansas Settlement area is much less permeable but more homogeneous than the aquifer in the Stewart area. The coefficient of transmissibility of the aquifers, which was estimated from the specific-capacity data, ranged from 58,000 to 160,000 gal. tons per day per foot. Prior to extensive ground-water pumpage, the ground-water system probably was in equilibrium, with discharge equaling recharge. At that time, ground water moved toward the playa, where it was discharged by transpiration and evaporation. The estimate of the evapotranspiration in the playa area before large-scale development was about 75,000 acre-feet per year. On the basis of estimates of coefficients of transmissibility of the aquifer and on the basis of the water-table configuration, underflow toward the playa was computed to be about 54,000 acre-feet per year. By 1963, large-scale pumping had caused marked changes in the shape of the piezometric surface; large cones of depression had developed, and ground-water movement was toward the centers of pumping. The cones of depression caused by large-scale pumping have since expanded, and water-level declines have been measured in the recharge areas along the mountain fronts. Ground water has been used for irrigation since 1910. In 1928, about 4,000 acre-feet of ground water was pumped, and by 1963 180,000 acre-feet per year was being pumped. An estimated 1,860,000 acre-feet of water has been pumped for irrigation in the Willcox basin through 1963; 680,000 acre-feet from the Stewart area, 990,000 acre-feet from the Kansas Settlement area, and 190,000 acre-feet from the Pearce-Cochise area. In the Sierra Bonita Ranch area and the north playa area, ground-water withdrawal for irrigation through 1963 was small. From the spring of 1952 to the spring of 1964 water-level declines resulting from the

Water Supply Paper↗
USGS1968

Storage requirements for Arkansas streams

The supply of good-quality surface water in Arkansas is abundant. owing to seasonal and annual variability of streamflow, however, storage must be provided to insure dependable year-round supplies in most of the State. Storage requirements for draft rates that are as much as 60 percent of the mean annual flow at 49 continuous-record gaging stations can be obtained from tabular data in this report. Through regional analyses of streamflow data, the State was divided into three regions. Draft-storage diagrams for each region provide a means of estimating storage requirements for sites on streams where data are scant, provided the drainage area, the mean annual flow, and the low-flow index are known. These data are tabulated for 53 gaging stations used in the analyses and for 132 partial-record sites where only base-flow measurements have been made. Mean annual flow can be determined for any stream whose drainage lies within the State by using the runoff map in this report. Low-flow indices can be estimated by correlating base flows, determined from several discharge measurements, with concurrent flows at nearby continuous-record gaging stations, whose low-flow indices have been determined.

Water Supply Paper↗
USGS1968

Electrical analog analysis of ground-water depletion in central Arizona

The Salt River Valley and the lower Santa Cruz River basin are the two largest agricultural areas in Arizona. The extensive use of ground water for irrigation has resulted in the need for a thorough appraisal of the present and future ground-water resources. The ground-water reservoir provides 80 percent (3.2 million acre-feet) of the total annual water supply. The amount of water pumped greatly exceeds the rate at which the ground-water supply is being replenished and has resulted in water-level declines of as much as 20 feet per year in some places. The depletion problem is of economic importance because ground water will become more expensive as pumping lifts increase and well yields decrease. The use of electrical-analog modeling techniques has made it possible to predict future ground-water levels under conditions of continued withdrawal in excess of the rate of replenishment. The electrical system is a representation of the hydrologic system: resistors and capacitors represent transmissibility and storage coefficients. The analogy between the two systems is accepted when the data obtained from the model closely match the field data in this instance, measured water-level change since 1923. The prediction of future water-table conditions is accomplished by a simple extension of the pumping trends to determine the resultant effect on the regional water levels. The results of this study indicate the probable depths to water in central Arizona in 1974 and 1984 if the aquifer characteristics are accurately modeled and if withdrawal of ground water continues at the same rate and under the tame areal distribution as existed between 1958 and 1964. The greatest depths to water in 1984 will be more than 700 feet near Stanfield and more than 650 feet in Deer Valley and northeast of Gilbert. South of Eloy and northwest of Litchfield Park, a static water level of more than 550 feet is predicted. The total water-level decline in the 20-year period 1964-84 at the deepest points of the major cones of depression will range from 150 to 300 feet, and the average decline in the entire central Arizona area will be about 100 feet.

Arizona↗