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At least 1,801 records · Page 100Linked to original sources
USGS1998

Hydrogeology, water quality, water budgets, and simulated responses to hydrologic changes in Santa Rosa and San Simeon Creek ground-water basins, San Luis Obispo County, California

Santa Rosa and San Simeon Creeks are underlain by thin, narrow ground-water basins that supply nearly all water used for local agricultural and municipal purposes. The creeks discharge to the Pacific Ocean near the northwestern corner of San Luis Obispo County, California. The basins contain heterogeneous, unconsolidated alluvial deposits and are underlain by relatively impermeable bedrock. Both creeks usually stop flowing during the summer dry season, and most of the pumpage during that time is derived from ground-water storage. Annual pumpage increased substantially during 1956?88 and is now a large fraction of basin storage capacity. Consequently, dry-season water levels are lower and the water supply is more vulnerable to drought. The creeks are the largest source of ground-water recharge, and complete basin recharge can occur within the first few weeks of winter streamflow. Agricultural and municipal pumpages are the largest outflows and cause dry-season water-level declines throughout the San Simeon Basin. Pumping effects are more localized in the Santa Rosa Basin because of subsurface flow obstructions. Even without pumpage, a large quantity of water naturally drains out of storage at the upper ends of the basins during the dry season. Ground water is more saline in areas close to the coast than in inland areas. Although seawater intrusion has occurred in the past, it probably was not the cause of high salinity in 1988?89. Ground water is very hard, and concentrations of dissolved solids, chloride, iron, and manganese exceed drinking-water standards in some locations. Probability distributions of streamflow were estimated indirectly from a 120-year rainfall record because the periods of record for local stream-gaging stations were wetter than average. Dry-season durations with recurrence intervals between 5 and 43 years are likely to dry up some wells but not cause seawater intrusion. A winter with no streamflow is likely to occur about every 32 years and to result in numerous dry wells, seawater intrusion, and subsidence. Digital ground-water-flow models were used to estimate several items in the ground-water budgets and to investigate the effects of pumpage and drought. The models also were used to investigate the hydrologic effects of selected water-resources management alternatives. Selection of alternatives was not constrained by issues related to water rights, which were under dispute during the study. Increases in the area and intensity of irrigation could increase agricultural water demand by 26 to 35 percent, an increase that would lower water levels by as much as 10 feet and possibly cause subsidence in the lower Santa Rosa Basin. An additional municipal well in the lower Santa Rosa Basin could withdraw 100 acre-feet per year without causing seawater intrusion, but subsidence might occur. Transferring 270 acre-feet per year of treated wastewater from a percolation area near the coast to an area about 0.5 mile upstream of the municipal well field in the San Simeon Basin could raise upstream water levels by as much as 12 feet without causing significant water-table mounding or seawater intrusion. Decreases in agricultural pumping after a winter without streamflow could prevent seawater intrusion while allowing municipal pumping to continue at normal rates.

Water-Resources Investigations Report↗
USGS1998

Effects of ice formation on hydrology and water quality in the lower Bradley River, Alaska — Implications for salmon incubation habitat

A minimum flow of 40 cubic feet per second is required in the lower Bradley River, near Homer, Alaska, from November 2 to April 30 to ensure adequate habitat for salmon incubation. The study that determined this minimum flow did not account for the effects of ice formation on habitat. The limiting factor for determining the minimal acceptable flow limit appears to be stream-water velocity. The minimum short-term flow needed to ensure adequate salmon incubation habitat when ice is present is about 30 cubic feet per second. For long-term flows, 40 cubic feet per second is adequate when ice is present. Long-term minimum discharge needed to ensure adequate incubation habitat--which is based on mean velocity alone--is as follows: 40 cubic feet per second when ice is forming; 35 cubic feet per second for stable and eroding ice conditions; and 30 cubic feet per second for ice-free conditions. The effects of long-term streamflow less than 40 cubic feet per second on fine-sediment deposition and dissolved-oxygen interchange could not be extrapolated from the data. Hydrologic properties and water-quality data were measured in winter only from March 1993 to April 1998 at six transects in the lower Bradley River under three phases of icing: forming, stable, and eroding. Discharge in the lower Bradley River ranged from 33.3 to 73.0 cubic feet per second during all phases of ice formation and ice conditions, which ranged from ice free to 100 percent ice cover. Hydrostatic head was adequate for habitat protection for all ice phases and discharges. Mean stream velocity was adequate for all but one ice-forming episode. Velocity distribution within each transect varied significantly from one sampling period to the next. No relation was found between ice phase, discharge, and wetted perimeter. Intragravel-water temperature was slightly warmer than surface-water temperature. Surface- and intragravel-water dissolved-oxygen levels were adequate for all ice phases and discharges. No apparent relation was found between dissolved-oxygen levels and streamflow or ice conditions. Fine-sediment deposition was greatest at the downstream end of the study reach because of low shear velocities and tide-induced deposition. Dissolved-oxygen interchange was adequate for all discharges and ice conditions. Stranding potential of salmon fry was found to be low throughout the study reach. Minimum flows from the fish-water bypass needed to maintain 40 cubic feet per second in the lower Bradley River are estimated.

Alaska↗
USGS1998

Recharge-area delineation and hydrology, McCraken Springs, Fort Knox Military Reservation, Meade County, Kentucky

McCraken Springs, consisting of three perennial springs - Main, Bat Cave, and Rocky Springs—and several intermittent springs, are used as a source of public water by the Fort Knox Military Reservation in Meade County, Ky. The water supply provided by McCraken Springs is potentially vulnerable to natural and induced stresses on the karst aquifer and to degradation by contaminants introduced by stormwater entering sinkholes and a large sinking stream in the Springs' recharge area. The U.S. Department of the Army is preparing a spring-basin protection plan for McCraken Springs, in accordance with State water-supply regulations and as specified under U.S. Environmental Protection Agency Guidelines for the Wellhead Protection Program (U.S. Environmental Protection Agency, 1991). In order to provide the information needed to prepare the plan, the U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps of Engineers, conducted a hydrogeologic study of the McCraken Springs in 1997-98. This report presents the results of that investigation. Ground-water-tracer tests and the results of potentiometric-surface mapping were used to identify ground-water basins drained by major perennial springs and to delineate the approximate boundaries of the recharge area for McCraken Springs. Additional hydrologic data were collected to determine the discharge and recharge characteristics of the Springs. Karst aquifers and springs are widely recognized as being more sensitive to degradation to point- and nonpoint-source contamination than most granular and fractured-rock aquifers (Field, 1990). Delineation of the geographic area contributing recharge to a water-supply spring is a principal step in identifying potential sources of ground-water contamination and developing a strategy to ensure the availability and protect the sustainability of the water supply. Conventional methods of aquifer testing and numerical modeling are not sufficient to determine the flow boundaries of ground-water basins in conduit-dominated karst aquifers. Previous studies published by Quinlan and Ewers (1989); Mull and others (1990); Bayless and others (1994); and Schindel and others (1995) demonstrate the utility of ground-water tracer tests, used in combination with potentiometric-surface mapping, to identify flow directions in karst aquifers, and to delineate karst ground-water-basin boundaries.

Kentucky↗
USGS1999

Hydrology and Water Quality of the Oljato Alluvial Aquifer, Monument Valley Area, Utah and Arizona

The Navajo Indian Reservation in Utah and Arizona is situated in one of the most arid parts of the Western United States. Normal annual precipitation is less than 8 to about 10 in. over much of the region (Cooley and others, 1969). Generally, water supplies for residents on the Reservation come from wells and springs, but locally, these supplies are small and, in some areas, they are slightly to moderately saline and not suitable for domestic purposes (Naftz and Spangler, 1994). One such area where water supply is limited is Monument Valley, along the Utah-Arizona State line, in the northern part of the Navajo Indian Reservation. The main issue identified by the Navajo Nation Department of Water Resources (DWR) concerns adequate water supply for the residents of the Monument Valley area. Additional water sources need to be developed locally to avoid having water piped into the area and to minimize haulage of water for domestic use. In addition, supplemental water supplies need to be developed to meet the demands of an increasing number of tourists. Because of these needs, the Navajo Nation DWR, in cooperation with the U.S. Geological Survey, investigated the hydrology of, and quality of water in, an alluvial aquifer along a tributary of Oljato Wash, near Oljato, Utah.

Water-Resources Investigations Report↗
USGS1999

Health of native riparian vegetation and its relation to hydrologic conditions along the Mojave River, southern California

The health of native riparian vegetation and its relation to hydrologic conditions were studied along the Mojave River mainly during the growing seasons of 1997 and 1998. The study concentrated on cottonwood-willow woodlands (predominantly Populus fremontii and Salix gooddingii ) and mesquite bosques (predominantly Prosopis glandulosa ). Tree-growth characteristics were measured at 16 cottonwood-willow woodland sites and at 3 mesquite bosque sites. Density of live and dead trees, tree diameter and height, canopy density, live-crown volume, leaf-water potential, leaf-area index, mortality, and reproduction were measured or noted at each site. The sites included healthy and reproducing woodlands and bosques, stressed woodlands and bosques with no reproduction, and woodlands and bosques with high mortality. Tree roots were studied at seven sites to determine the vertical distribution of the root system and their relation to the water table at healthy, stressed, and high-mortality cottonwood-willow woodlands. In the six trenches that were dug for this study in May 1997, no cottonwood roots were observed that reached the water table. The root systems of healthy trees typically ended 1 to 2 feet above the water table. At sites with high mortality, the main root mass was commonly 7 to 8 feet above the water table. Water-table depth was monitored at each of the study sites. In addition, volumetric soil moisture and soil-water potential were monitored at varying depths at three cottonwood-willow woodland study sites and at two mesquite bosque sites. Ground, soil, river, lake, and plant (xylem sap) water were analyzed for concentrations of stable hydrogen and oxygen isotopes to determine the source of water used by the trees. On the basis of the root-distribution, soil- and leaf-water potential, and isotope data, it was concluded that cottonwood, willow, and mesquite trees mainly rely on ground water for their perennial sustained supply of water. The trees mainly utilize ground water that has moved upward from the water table into the capillary fringe and into unsaturated soil nearer to land surface. Most precipitation (average is 4 to 6 inches per year) is lost by evaporation and by transpiration of shallow-rooted xeric plants, and very little reaches the root zone of trees along the Mojave River. Water-table depth had no strong correlation to many individual tree-growth characteristics, such as density, diameter, height, and live-crown volume. However, leaf-area index (corrected for stem area) of both healthy and stressed cottonwood-willow woodlands had a highly significant statistical relation to water-table depth, and a curvilinear regression model was defined. As in cottonwood-willow woodlands, leaf-area index of mesquite bosques also decreased with increased water-table depth. However, because of the small number of sites, no significant statistical relation could be defined for mesquite bosques. Because it can be accurately measured repeatedly at the same locations, leaf-area index (corrected for stem area) is recommended as the primary growth characteristic that should be monitored. Future vegetation changes along the Mojave River can be quantified using the sites established for this study. Mortality was as high as 39 percent in healthy cottonwood-willow woodlands, but mortality of 50 to 100 percent was common where water-table depth was greater than about 7 feet or in areas where permanent water-table declines greater than about 5 feet had occurred. At a healthy mesquite bosque where the water-table depth ranged from about 8 to 11 feet, mortality was about 20 percent. Where the water table had been lowered an additional 10 to 25 feet by pumping, mortality of the mesquite was extremely high (80 to 99 percent). On the basis of observations of plant reproduction, it was concluded that established cottonwood-willow woodlands probably will reproduce, mainly by root sprouting of mature trees, if the water-table depth during spring and early summer is less than about 5 feet and if there is sufficient sunlight. Likewise, reproduction in established mesquite bosques will probably occur by root sprouting if the water-table depth during spring and early summer is less than about 8 feet. Germination of cottonwood and willow seeds is common during spring in dry channels following winter stormflows in the Mojave River. However, most of the seedlings die before their roots reach a perennial water supply near the water table, and established stands of trees resulting from seed germination are rare.

California↗
USGS1999

Hydrology, geomorphology, and flood profiles of the Mendenhall River, Juneau, Alaska

Water-surface-profile elevations for the 2-, 20-, 25-, 50-, and 100-year floods were computed for the Mendenhall River near Juneau, Alaska, using the U.S. Army Corps of Engineers Hydrologic Engineering Center River Analysis System model. The peak discharges for the selected recurrence intervals were determined using the standard log-Pearson type III method. Channel cross sections were surveyed at 60 locations to define hydraulic characteristics over a 5.5-mile reach of river beginning at Mendenhall Lake outlet and extending to the river mouth. A peak flow of 12,400 cubic feet per second occurred on the Mendenhall River on October 20, 1998. This discharge is equivalent to about a 10-year flood on the Mendenhall River and floodmarks produced by this flood were surveyed and used to calibrate the model. The study area is currently experiencing land-surface uplift rates of about 0.05 foot per year. This high rate of uplift has the potential to cause incision or downcutting of the river channel through lowering of the base level. Vertical datum used in the study area was established about 37 years before the most recent surveys of river-channel geometry. The resulting difference between land-surface elevations and sea level continues to increase. Continuing incision of the river channel combined with increased land-surface elevations with respect to sea level may result in computed flood profiles that are higher than actual existing conditions in the tidally influenced reach of the river.

Alaska↗
USGS1999

Hydrologic effects of the Pymatuning earthquake of September 25, 1998, in northwestern Pennsylvania

Within hours after the Pymatuning earthquake of September 25, 1998, in northwestern Pennsylvania, local residents reported wells becoming dry, wells beginning to flow, and the formation of new springs. About 120 household-supply wells reportedly went dry within 3 months after the earthquake. About 80 of these wells were on a ridge between Jamestown and Greenville, where water-level declines of as much as 100 feet were documented. Accompanying the decline in water levels beneath the ridge was an increase in water levels in valley wells of as much as 62 feet. One possible explanation of the observed hydrologic effects is that the earthquake increased the vertical hydraulic conductivity of shales beneath the ridge, which allowed ground water to drain from the hilltops. Computer simulations of ground-water flow beneath the ridge between Jamestown and Greenville indicate that increasing the vertical hydraulic conductivity of shale confining beds about 10 to 60 times from their pre-quake values could cause the general pattern of decreased water levels on hilltops and increased levels in valleys.

Pennsylvania↗
USGS2000

Hydrology and water quality of Little Cross Creek, Cumberland County, North Carolina, 1996-98

Little Cross Creek is a small stream located in Cumberland County, North Carolina, in the Sand Hills area of the Coastal Plain Province. From August 1996 through August 1998, the U.S. Geological Survey collected streamflow, water-quality, and time-of-travel data at 10 sites in Little Cross Creek Basin to assess ambient conditions and compute loads of suspended sediment, total nitrogen, total phosphorus, and total organic carbon. Streamflows in the Little Cross Creek Basin responded to climatic factors and to human activities such as water withdrawals and controlled releases from impoundments. Peak streamflows were observed during the passages of Hurricane Fran in September 1996 and Hurricane Josephine in October 1996. Streamflows generally were lowest during the summer and early fall of 1997, reflecting drought conditions associated with a prevailing El Nino. At most sites, average streamflow per unit drainage area, or yield, was higher than yields reported previously for the Sand Hills. High yields may have resulted from unidentified inputs of water to the study basins or from underestimation of the contributing drainage area. Bonnie Doone Lake, Kornbow Lake, Mintz Pond, and Glenville Lake, four impoundments of Little Cross Creek, notably influence hydrology and water quality in the basin. Streamflow records indicate that these impoundments dampen peak stormflows and delay the downstream release of stormwater. Time of travel also is affected by seasonal stratification in the reservoirs. In general, sites downstream from reservoirs have lower concentrations of suspended sediment, turbidity, and total phosphorus than sites upstream from reservoirs or sites that receive stormwater runoff. Few water-quality problems were observed in the Little Cross Creek Basin for the constituents that were sampled. However, fecal coliform bacteria commonly exceeded 200 colonies per 100 milliliters at two of the seven monitored sites during the study. Relatively high concentrations of specific conductance, total phosphorus, and total ammonia plus organic nitrogen were observed in Clark Pond Creek, a tributary to Little Cross Creek. Loads and yields of suspended sediment, total nitrogen, total phosphorus, and total organic carbon were computed for the period from October 1996 through September 1997. The highest suspended-sediment yield (230 tons per square mile per year) occurred upstream from Bonnie Doone Lake, probably because there were no impoundments upstream from this site to intercept sediment. Sediment yields at the remaining Little Cross Creek sites were low relative to yields reported from other urban basins in North Carolina. Downstream from Kornbow Lake, yields of suspended sediment (9.50 tons per square mile per year) and total phosphorus (0.011 ton per square mile per year) were very low. Clark Pond Creek had the highest yields ot total phosphorus (0.081 ton per square mile per year) and total organic carbon (11.5 tons per square mile per year). However, total phosphorus yields at all of the Little Cross Creek sites generally were lower than yields measured in other urban basins in the State. Comparison of inflow and outflow loads for the four Little Cross Creek reservoirs from October 1996 through September 1997 indicated that Bonnie Doone Lake trapped 92 percent of incoming sediment and 37 percent of incoming total phosphorus. Kornbow Lake trapped 57 percent of incoming sediment and 77 percent of total phosphorus inputs. Nitrogen was not effectively trapped by any of the reservoirs. An influx of sediment, total phosphorus, and total organic carbon was noted at a site downstream from Mintz Pond, and may have resulted from stormwater discharge from the U.S. Highway 401 bypass or from additional, unidentified sources in the watershed downstream from Kornbow Lake.

North Carolina↗
USGS1961

Hydraulic and hydrologic aspects of flood-plain planning

The valid incentives compelling occupation of the flood plain, up to and eve n into the stream channel, undoubtedly have contributed greatly to the development of the country. But the result has been a heritage of flood disaster, suffering, and enormous costs. Flood destruction awakened a consciousness toward reduction and elimination of flood hazards, originally manifested in the protection of existing developments. More recently, increased knowledge of the problem has shown the impracticability of permitting development that requires costly flood protect/on. The idea of flood zoning, or flood-plain planning, has received greater impetus as a result of this realization. This study shows how hydraulic and hydrologic data concerning the flood regimen of a stream can be used in appraising its flood potential and the risk inherent in occupation of its flood plain. The approach involves the study of flood magnitudes as recorded or computed; flood frequencies based1 on experience shown by many years of gaging-station record; use of existing or computed stagedischarge relations and flood profiles; and, where required, the preparation of flood-zone maps to show the areas inundated by floods of several magnitudes and frequencies. The planner can delineate areas subject to inundation by floods o* specific recurrence intervals for three conditions: (a) for the immediate vicinity of a gaging station; (b) for a gaged stream at a considerable distance from a gaging station; and (c) for an ungaged stream. The average depth for a flood of specific frequency can be estimated on the basis of simple measurements of area of drainage basin, width of channel, and slope of streambed. This simplified approach should be useful in the initial stages of flood-plain planning. Brief discussions are included on various types of flood hazards, the effects of urbanization on flood runoff, and zoning considerations.

Pennsylvania↗
USGS1963

Hydrologic and biotic characteristics of grazed and ungrazed watersheds of the Badger Wash basin in western Colorado, 1953-58

A comprehensive study of the hydrologic and biotic characteristics of small drainage basins on the Colorado Plateau and the effect of grazing on these characteristics vas begun in 1953. This report presents data obtained during the first 5 years of the proposed 20-year study. Periodic observations were made at permanent transects in 8 paired fenced and unfenced watersheds to characterize plant and ground cover, determine degree of use by livestock and measure changes in watershed cover. Results after 5 years of study indicate that changes in watershed cover have been relatively small on both grazed and ungrazed areas. Changes that did take place were mainly on shale and mixed type .soil. Ground-cover index on mixed type soil was significantly higher, 4 percent, on ungrazed ,areas than on grazed areas at the end of 5 years. Plot records were obtained using the Rocky Mountain Infiltrameter at 12 plots in each of the 8 study watersheds to determine the effect of livestock exclusion on infiltration and sheet erosion. Infiltration rates for the last 20 minutes of both the wet .and dry runs were significantly higher in 1958 than they were 5 years before, but this difference was not associated with treatment because rates on both grazed and ungrazed plots increased about .the same amount. The initial water-absorbing capacity increased significantly on ungrazed plots. No change in erosion rates was observed. Rainfall was variable and below normal during 4 of the first 5 years of study. Runoff was produced mainly by thunderstorms during the summer months and was characterized by high rates of flow for short periods. Comparison of runoff in grazed and ungrazed watersheds indicates a change in the relation between precipitation and runoff because of exclusion of livestock. More sediment per unit area was produced during the 5 years of study from grazed .areas than from ungrazed areas. No definite trend in small mammal population on grazed and ungrazed water- sheds has yet been determined. Results of preliminary studies on rabbit population indicates that rabbits prefer to inhabit ungrazed areas, but populations were judged to be not high in any area.

Colorado↗
USGS1971

Effects of Grazing on the Hydrology and Biology of the Badger Wash Basin in Western Colorado, 1953-66

An intensive study of the effect of grazing on the hydrologic and biotic characteristics of small drainage basins on the Colorado Plateau was begun in the fall of 1953. This report presents data obtained during the first 13 years of the proposed 20-year study. For the period of record 1954-66, runoff from grazed watersheds has averaged about 33 acre-feet per square mile per year. Runoff from ungrazed watersheds averaged from 71 to 76 percent of that from grazed watersheds. During the last 6 years of the period, however, ungrazed watersheds produced 69 to 71 percent as much runoff as grazed watersheds. The sediment yield frown grazed watersheds during the same period was about 3 acre-feet per square mile per year. Sediment yield from ungrazed watersheds ranged from 51 to 75 percent of that from grazed watersheds and averaged 66 percent. The largest change in these relations occurred about 2 years after livestock were excluded from certain watersheds. The causative factors for changes in the runoff and sediment yield relations are not entirely clear. At the end of 13 years, a significant change had occurred in the amount of bare soil and rock. in the ground-cover index, and in the litter and moss on the grazed watersheds. These items remained essentially unchanged on ungrazed watersheds. The changes in ground-cover factors were not of large magnitude and did not occur at the same rate as the changes in runoff and sediment yield. A large part of the difference appears to have been caused by a change in the structure of surface soil. which was brought about by the elimination of trampling by livestock. Deer mice were the most common rodent present on the experimental watersheds, but even their population was not great enough to affect the composition of range vegetation. Deer mice populations remained comparable on grazed and ungrazed watersheds during the study. Other rodents were not present in sufficient numbers to allow their comparison on grazed and ungrazed range. Desert cottontail rabbits and black-tailed jackrabbits were more plentiful in ungrazed watersheds but were not present in large enough numbers to affect range vegetation.

Water Supply Paper↗
USGS1960

Flood-frequency analyses, Manual of Hydrology: Part 3

This report describes the method used by the U.S. Geological Survey to determine the magnitude and frequency of momentary peak discharges at any place on a stream, whether a gaging-station record is available or not. The method is applicable to a region of any size, as a river basin or a State, so long as the region is hydrologically homogeneous. The analysis provides two curves. The first expresses the flood discharge-time relation, showing variation of peak discharge, expressed as a ratio to the mean annual flood, with recurrence interval. The second relates the mean annual flood to the size of drainage area alone, or to the size area and other significant basin characteristics. A frequency curve may be defined for any place in the region by use of these two curves. The procedure is: (a) measure the drainage area and other appropriate basin characteristics from maps; (b) from the second curve, select the mean annual flood corresponding to the proper drainage area factors; (c) from the first curve, select ratios of peak discharge to mean annual flood for selected recurrence intervals, as 2, 10, 25, and 50 years; and (d) multiply these ratios by the mean annual flood and plot the resulting discharges of known frequency to define the frequency curve. Two reports not previously given general circulation are included as sections of this report. These are 'Plotting Positions in Frequency Analysis' by W. B. Langbein, and 'Characteristics of Frequency Curves Based on a Theoretical 1,000-Year Record' by M. A. Benson.

Water Supply Paper↗
USGS1961

Water quality and hydrology in the Fort Belvoir area, Virginia, 1954-55

This report summarizes the results of an investigation of water quality and hydrology in the Fort Belvoir, Va., area for the period August 1954 to September 1955. It summarizes and evaluates information about the water resources of this area that are pertinent to the choice of location and operation of an Army nuclear power reactor. The quantity, quality, nature, and use of the local water that might be affected by the location and operation of a reactor in the area were subjects of investigation. Variations in the quality of the water caused by variation in streamflow, tidal effects, and pollution were important facets of the investigation. During extended periods of low streamflow in the Potomac River (usually in the late summer months), salty water moves upstream from Chesapeake Bay and increases the dissolved solids content of the surface waters adjacent to Fort Belvoir. When the streamflow is low the concentration of dissolved solids in the water near the river bottom exceeds that near the surface. The waters in Gunston Cove usually contain more dissolved oxygen than those in the Potomac River. During the summer, the content of dissolved oxygen in the cove waters frequently exceeds 100 percent of saturation. Surface floats that were released on a flood tide in Gunston Cove moved toward the inner portion of the cove in the same direction as the wind and the tide. The maximum average velocity of these floats was 0.65 feet per second. On an ebb tide, many surface floats that were released in Gunston Cove moved toward the inner portion of the cove in the direction of the wind, in opposition to the direction of the tidal movement. Floats released near the mouth of the cove on the same tide, moved with the tide out of the cove through a narrow pass at the end of a submerged sandbar extending from the Fort Belvoir shoreline. The maximum average velocity of the floats in the pass on this ebb tide was 0.85 feet per second. Measurements of subsurface flow direction indicate that the water in the deeper part of Gunston Cove tended to move toward Accotink Bay on the flood tide and out of the cove into the Potomac River on the ebb tide. The water 150-500 feet offshore from the reactor site tended to move toward Accotink Bay on the flood tide and toward Pohick Bay on the ebb tide, whereas waters 30 feet from the Fort Belvoir shoreline tended to move counterclockwise during part of the time. In Gunston Cove the maximum measured flood velocity was 0.48 feet-per second, and the maximum ebb velocity was 0.71 per second. During periods of low streamflow, pollutants that enter the Potomac River at Fort Belvoir may move as much as 5.5 miles upstream on a flood tide and as much as 5 miles downstream on an ebb tide. At higher flow rates movement of pollutants is less upstream and greater downstream. The time required to flush the 10-mile reach of the Potomac River adjacent to Fort Belvoir varies from a day or two at high-flow rates to several weeks at low-flow rates.

Water Supply Paper↗
USGS1967

Geology and hydrology between Lake McMillan and Carlsbad Springs, Eddy County, New Mexico

The hydrology of the Pecos River valley between Lake McMillan and Carlsbad Springs, Eddy County, N. Mex., is influenced by facies changes in rocks of Permian age. Water stored for irrigation leaks from Lake McMillan into evaporite rocks, principally gypsum, of the Seven Rivers Formation and from Lake Avalon into carbonate rocks of the Tansill Formation. This leakage returns to the Pecos River at Major Johnson Springs and Carlsbad Springs. The river has perennial flow between Major Johnson Springs and Lake Avalon, but it loses water into evaporite rocks of the Yates Formation in this reach. Ground-water movement is generally toward the Pecos River in aquifers in the Pecos River valley except in the Rustler Formation east of the river where it moves southeastward toward playas east of Lake Avalon. The chloride content of ground and surface waters indicates that surface water moves from some reaches of the Pecos River and from surface-storage reservoirs to aquifers and also indicates the degree of mixing of ground and surface waters. About 45,000 acre-feet of ground water is stored in highly permeable rocks in a 3-mile wide part of the Seven Rivers Formation between Lake McMillan and Major Johnson Springs. This water in storage comes from leakage from Lake McMillan and from alluvium north of the springs. The flow of Major Johnson Springs is derived from this aquifer. That part of the flow derived from the alluvium north of the springs averaged 13 cfs (cubic feet per second) from 1953 through 1959 ; about 8 cfs of this flow had not been previously measured at gaging stations on the Pecos River and its tributaries. The most favorable plans for increasing terminal storage of the Carlsbad Irrigation District are to construct a dam at the Brantley site (at the downstream end of Major Johnson Springs), or to use underground storage in the permeable Seven Rivers Formation between Lake McMillan and Major Johnson brings in conjunction with surface storage. To avoid excessive leakage from a reservoir at the Brantley site, the dam should be downstream from all sprints in the Major Johnson Springs area but upstream from a point where the river begin losing water to the Yates Formation.

Water Supply Paper↗
USGS1970

Hydrologic effects of floodwater-retarding structures on Garza-Little Elm Reservoir, Texas

The Texas District of the Water Resources Division of the U.S. Geological Survey has collected and analyzed hydrologic data since 1953 to define the effects of systems of floodwater-retarding structures on downstream water and sediment yield. The district project includes 11 study areas ranging from 18 to 80 square miles in size and from 0 to 67 in percent of study area controlled by floodwaterretarding structures. The 11 study areas are within that part of Texas where the west-to-east average annual runoff ranges from about 2 to 7 inches. This report presents results of analyses, development of methodolgy, and results of application of methods for defining the downstream effects of systems of floodwaterretarding structures. Annual inflow to and outflow from the system of floodwater-retarding reservoirs in seven of the 11 study areas were found to be related by the equation: O=0.98/ 0.68, where O is annual outflow, in inches, and / is annual net inflow, in inches. Transmission loss of structure outflow to the downstream study-area stream-gaging station was determined and compared with the transmission loss of natural flood flow between tandem stream-gaging stations on Denton Creek, a tributary to Elm Fork Trinity River above Dallas. Trap efficiency of most floodwater-retarding structures was found by the U.S. Soil Conservation Service to be about 97 percent. Downstream increases in suspended-sediment concentration in the outflow were found to be large in a study area with mostly silt and clay sediments, but even a large increase in suspendedsediment concentration did not represent a significant quantitative pickup of sediment by the outflow water. Water consumption in floodwater-retarding reservoirs from the combined actions of evaporation, evapotranspiration, and seepage was found to be as much as twice the average annual consumption attributable to evaporation alone. Average annual consumption in reservoirs in the seven study areas analyzed ranged from 1.57 inches of equivalent runoff in the easternmost study area, where annual runoff averaged 6.96 inches, to 0.77 inch of equivalent runoff in the westernmost study area, where the average annual runoff was 2.35 inches. The effect of consumption on downstream flow is partially offset by rainfall on pool surface. Studies covering as much as 15 years of streamflow record at the stream-gaging stations that gage outflow from the Deep and Honey Creek study areas indicated no increase in base flow. Multiple-linear-regression techniques were used in developing methodology to determine reservoir consumption in seven study areas. The physical and climatic fnctors influencing consumption were grouped as variables in regard to their relative effect on the actions of evaporation, evapotranspiration, and seepage. The resulting generalized equation was then used in synthesizing the consumptive effects of a planned system of 162 floodwater-retarding reservoirs controlling 26 percent of a 1,660-square-mile drainage basin upstream from a major water-supply reservoir. The analyses were based on the assumption that all water consumed at the floodwater-retarding reservoirs would have reached the downstream watersupply reservoir. Water-sediment discharge relationships were derived for the runoff into the structures as well as for the runoff through and below the structures. A mathematical response model of the floodwater-retarding reservoir systems and the entire drainage basin was computer programed to yield monthly water and sediment inflow to the water-supply reservoir. Results of the response model showed that with full development, depletion of annual yield to the large reservoir would be as much as 10 percent in the early years; but after the permanent pools of the floodwater-retarding structures had mostly filled with sediment, depletion of annual yield would be generally less than 1 percent. The depletion of yield to Garza-Little Elm Reservoir during the 39-year synthesized period of study was estimated as 296,800 acre-feet out of 18,256,000 acre-feet total yield. During the same period, the floodwater-retarding structures were estimated to have kept 19,700 acre-feet of sediment from being deposited in the reservoir. "Firm"- or "critical"-yield studies were made of the large reservoir on the basis of two sets of conditions : with floodwater-retarding structures in the drainage basin, and without such structures. Results of the firm-yield studies indicated that with full development, annual firm yield would be initially reduced by 10 percent. After 30 or more years, when the permanent pools of the floodwaterretarding reservoirs would be mostly filled with sediment, the firm yield would be almost the same with or without the upstream development.

Texas↗
USGS1972

Hydrologic interpretations based on infrared imagery of Long Island, New York

Six remote-sensing flights over Long Island's north and south shores were made during the period July 13, 1967, to February 25, 1970. Infrared imagery in the 8- to 14-micrometer range was obtained; results varied from poor to excellent in quality. The ability of the RS 7 and Reconofax IV imagers to discern thermal contrasts of as little .as 1 ? to 2?C (Celsius) permitted identification of areas of heavy ground-water discharge. These areas were concentrated primarily along the eroded headlands of the north shore and in the lower reaches of watercourses draining into Great South Bay. Only a few highly localized examples of direct ground-water discharge into the embankments ,along Long Island's south shore were detected in the imagery. Thermal loading emanating from a powerplant near Oceanside is shown to be quickly dissipated in Middle Bay. Specific examples show that infrared imagery may ,also be used to identify circulation patterns, ice cover, changes in stream-temperature regimen, and the location of sewer outfalls. Optimal time for the collection of infrared imagery for hydrologic studies on Long Island is in summer and in winter, when surface-water thermal differences are relatively large.

Water Supply Paper↗
USGS1981

Hydrologic reconnaissance of the Wasatch Plateau-Book Cliffs coal-fields area, Utah

Data obtained during a hydrologic reconnaissance in 1975-77 in the Wasatch Plateau-Book Cliffs coal-fields area of Utah were correlated with existing long-term data. Maps were prepared showing average precipitation, average streamflow, stream temperature, ground- and surface-water quality, sediment yield, and geology. Recommendations were made for additional study and suggested approaches for continued monitoring in the coalfields areas. moDuring the 1931-75 water years, the minimum discharges for the five major streams that head in the area ranged from about 12,000 to 26,000 acre-feet per year, and the maximum discharges ranged from about 59,000 to 315,000 acre-feet per year. Correlations indicate that 3 years of low-flow records at stream sites in the Wasatch Plateau would allow the development of relationships with long-term sites that can be used to estimate future low-flow records within a standard error of about 20 percent. Most water-quality degradation in streams occurs along the flanks of the Wasatch Plateau and Book Cliffs. In the uplands, dissolved-solids concentrations generally ranged from less than 100 to about 250 milligrams per liter, and in the lowlands, the concentrations ranged from about 250 to more than 6,000 milligrams per liter. Most springs in the Wasatch Plateau and Book Cliffs discharge from the Star Point Sandstone or younger formations, and the water generally contains less than about 1,000 milligrams per liter of dissolved solids. The discharges of 65 springs ranged from about 0.2 to 200 gallons per minute. The Blackhawk Formation, which is the principal coal-bearing formation, produces water in many of the mines. The dissolved-solids concentration in water discharging from springs and mines in the Blackhawk ranged from about 60 to 800 milligrams per liter. In the lowland areas, the Ferron Sandstone Member of the Maneos Shale appears to have the most potential for subsurface development of water of suitable chemical quality for human consumption. Three wells in the Ferron yielded water with dissolved-solids concentrations ranging from about 650 to 1,230 milligrams per liter.

Utah↗
USGS1981

Hydrologic effects of stress-relief fracturing in an Appalachian Valley

A hydrologic study at Twin Falls State Park, Wyoming County, West Virginia, was made to determine how fracture systems affect the occurrence and movement of ground water in a typical valley of the Appalachian Plateaus Physiographic Province. Twin Falls was selected because it is generally unaffected by factors that would complicate an analysis of the data. The study area was the Black Fork Valley at Twin Falls. The valley is about 3 miles long and 400 to 600 feet wide and is cut into massive sandstone units interbedded with thin coal and shale beds. The study was made to determine how aquifer characteristics were related to fracture systems in this valley, so that the relation could be applied to studies of other valleys. Two sites were selected for test drilling, pumping tests, and geophysical studies. One site is in the upper part of the valley, and the second is near the lower central part. At both sites, ground water occurs mainly in horizontal bedding-plane fractures under the valley floor and in nearly vertical and horizontal slump fractures along the valley wall. The aquifer is under confined conditions under the valley floor and unconfined conditions along the valley wall. The fractures pinch out under the valley walls, which form impermeable barriers. Tests of wells near the valley center indicated a change in storage coefficient as the cone of depression caused by pumping reached the confined-unconfined boundaries; the tests also indicated barrier-image effects when the cone reached the impermeable boundaries. Drawdown from pumping near the center of the valley affected water levels at both sites, indicating a hydraulic connection from the upper to the lower end of the valley. Stream gain-and-loss studies show that ground water discharges to the stream from horizontal fractures beneath Black Fork Falls, near the mouth of Black Fork. The fracture systems that constitute most of the transmissive part of the aquifer at Twin Falls are like those described as being formed from stress relief. As stress-relief fractures have been described in other valleys of the Appalachian Plateaus, the same aquifer conditions may exist in those valleys.

Water Supply Paper↗

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