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At least 739 records · Page 41Linked to original sources
USGS2005

Statistical summaries of streamflow in Montana and adjacent areas, water years 1900 through 2002

In response to the need to have more current information about streamflow characteristics in Montana, the U.S. Geological Survey, in cooperation with the Montana Department of Environmental Quality, Confederated Salish and Kootenai Tribes, and Bureau of Land Management, conducted a study to analyze streamflow data. Updated statistical summaries of streamflow characteristics are presented for 286 streamflow-gaging sites in Montana and adjacent areas having 10 or more years of record for water years 1900 through 2002. Data include the magnitude and probability of annual low and high flow, the magnitude and probability of low flow for three seasons (March-June, July-October, and November-February), flow duration of the daily mean discharge, and the monthly and annual mean discharges. For streamflow-gaging stations where 20 percent or more of the contributing drainage basin is affected by dams or other large-scale human modification, streamflow is considered regulated. Separate streamflow characteristics are presented for the unregulated and regulated periods of record for sites with sufficient data.

Scientific Investigations Report↗
USGS2014

Hydrogeology, water resources, and water budget of the upper Rio Hondo Basin, Lincoln County, New Mexico, 2010

The upper Rio Hondo Basin occupies a drainage area of 585 square miles in south-central New Mexico and comprises three general hydrogeologic terranes: the higher elevation “Mountain Block,” the “Central Basin” piedmont area, and the lower elevation “Hondo Slope.” As many as 12 hydrostratigraphic units serve as aquifers locally and form a continuous aquifer on the regional scale. Streams and aquifers in the basin are closely interconnected, with numerous gaining and losing stream reaches across the study area. In general, the aquifers are characterized by low storage capacity and respond to short-term and long-term variations in recharge with marked water-level fluctuations on short (days to months) and long (decadal) time scales. Droughts and local groundwater withdrawals have caused marked water-table declines in some areas, whereas periodically heavy monsoons and snowmelt events have rapidly recharged aquifers in some areas. A regional-scale conceptual water budget was developed for the study area in order to gain a basic understanding of the magnitude of the various components of input, output, and change in storage. The primary input is watershed yield from the Mountain Block terrane, supplying about 38,200 to 42,300 acre-feet per year (acre-ft/yr) to the basin, as estimated by comparing the residual of precipitation and evapotranspiration with local streamgage data. Streamflow from the basin averaged about 21,200 acre-ft/yr, and groundwater output left the basin at an estimated 2,300 to 5,700 acre-ft/yr. The other major output (about 13,500 acre-ft/yr) was by public water supply, private water supply, livestock, commercial and industrial uses, and the Bonito Pipeline. The residual in the water budget, the difference between the totals of the input and output terms or the potential change in storage, ranged from -2,200 acre-ft/yr to +5,300 acre-ft/yr. There is a high degree of variability in precipitation and consequently in the water supply; small variations in annual precipitation can result in major changes in overall watershed yield. Changing water-use patterns, concentrated areas of groundwater withdrawal, and variations in precipitation have created localized areas where water-table declines and diminished surface flow are of concern.

Lincoln, New Mexico↗
USGS2025

Simulated hydrologic responses to proposed wastewater-returnflow scenarios in Falmouth, Massachusetts

The Cape Cod aquifer is the sole source of drinking water for communities on Cape Cod, Massachusetts, including the Town of Falmouth, where the aquifer is currently threatened by contamination from septic-system-derived nitrogen. To address this problem, the Town is proposing to sewer areas of Falmouth, treat the wastewater at the Town’s Main Wastewater Treatment Facility (a nitrogen removing/tertiary treatment facility), and discharge the treated wastewater to an ocean outfall pipe in Nantucket Sound. The U.S. Geological Survey, in cooperation with the Town of Falmouth, updated a three-dimensional steady-state groundwater flow model to represent current (defined as 2019–23) average hydrologic conditions and to simulate the long-term average freshwater hydrologic response to two wastewater-return-flow scenarios. Scenario 1 involves the sewering of all properties south of Route 28 in Falmouth, which approximates the Town’s possible sewer expansion over the next 20–30 years. Scenario 2 involves sewering of all properties in Falmouth to demonstrate the maximum potential effect of sewering on the aquifer. Overall, the simulated hydrologic response of water-table altitudes and streamflow in both scenarios was relatively small compared to fluctuations from natural recharge. In scenario 1, the water-table altitude decreased by about 0.1 feet south of Route 28, where the conversion to municipal sewers removed wastewater-return flow from onsite septic systems. The water-table altitude decreased by about 0.1–0.2 feet over a larger area in Falmouth under town-wide sewering in scenario 2. The greatest decrease in water-table altitude in both scenarios occurred near the Main Wastewater Treatment Facility, with a decrease of about 1.1 feet in scenario 1 and about 1.3 feet in scenario 2. Simulated decreases in streamflow also were estimated for six selected streams in Falmouth and Mashpee. In both scenarios, the largest simulated decreases in streamflow were at the Coonamessett River, which is the closest stream to the Main Wastewater Treatment Facility. In scenario 1, the average annual decrease in flow at the Coonamessett River was 0.1 cubic feet per second, a 1.1 percent decrease from current (2019–23) conditions. In scenario 2, streamflow at the Coonamessett River decreased by 0.6 cubic feet per second, a 5.4 percent decrease from current (2019–23) conditions.

Massachusetts↗
USGS2001

Simulation of ground-water discharge to Biscayne Bay, southeastern Florida

As part of the Place-Based Studies Program, the U.S. Geological Survey initiated a project in 1996, in cooperation with the U.S. Army Corps of Engineers, to quantify the rates and patterns of submarine ground-water discharge to Biscayne Bay. Project objectives were achieved through field investigations at three sites (Coconut Grove, Deering Estate, and Mowry Canal) along the coastline of Biscayne Bay and through the development and calibration of variable-density, ground-water flow models. Two-dimensional, vertical cross-sectional models were developed for steady-state conditions for the Coconut Grove and Deering Estate transects to quantify local-scale ground-water discharge patterns to Biscayne Bay. A larger regional-scale model was developed in three dimensions to simulate submarine ground-water discharge to the entire bay. The SEAWAT code, which is a combined version of MODFLOW and MT3D, was used to simulate the complex variable-density flow patterns. Field data suggest that ground-water discharge to Biscayne Bay relative to the shoreline is restricted to within 300 meters at Coconut Grove, 600 to 1,000 meters at Deering Estate, and 100 meters at Mowry Canal. The vertical cross-sectional models, which were calibrated to the field data using the assumption of steady state, tend to focus ground-water discharge to within 50 to 200 meters of the shoreline. With homogeneous distributions for aquifer parameters and a constant-concentration boundary for Biscayne Bay, the numerical models could not reproduce the lower ground-water salinities observed beneath the bay, which suggests that further research may be necessary to improve the accuracy of the numerical simulations. Results from the cross-sectional models, which were able to simulate the approximate position of the saltwater interface, suggest that longitudinal dispersivity ranges between 1 and 10 meters, and transverse dispersivity ranges from 0.1 to 1 meter for the Biscayne aquifer. The three-dimensional, regional-scale model was calibrated to ground-water heads, canal baseflow, and the general position of the saltwater interface for nearly a 10-year period from 1989 to 1998. The mean absolute error between observed and simulated head values is 0.15 meter. The mean absolute error between observed and simulated baseflow is 3 x 105 cubic meters per day. The position of the simulated saltwater interface generally matches the position observed in the field, except for areas north of the Miami Canal where the simulated saltwater interface is located about 5 kilometers inland of the observed saltwater interface. Results from the regional-scale model suggest that the average rate of fresh ground-water discharge to Biscayne Bay for the 10-year period (1989-98) is about 2 x 105 cubic meters per day for 100 kilometers of coastline. This simulated discharge rate is about 6 percent of the measured surface-water discharge to Biscayne Bay for the same period. The model also suggests that nearly 100 percent of the fresh ground-water discharge is to the northern half of Biscayne Bay, north of the Cutler Drain Canal. South of the Cutler Drain Canal, coastal lowlands prevent the water table from rising high enough to drive measurable quantities of ground water to Biscayne Bay. Annual variations in sea-level elevation, which can be as large as 0.3 meter, have a substantial effect on rates of ground-water discharge. During 1989-98, simulated rates of ground-water discharge to Biscayne Bay generally are highest when sea level is relatively low.

Florida↗
USGS1984

Ground-water conditions in the Cottonwood-West Oakley Fan area, south-central Idaho

Intensive groundwater development in the Cottonwood-West Oakley Fan area, Cassia County, Idaho, has resulted in rapid water-level declines and establishment of two critical groundwater areas. A northwest-trending fault in nearly coincident with the boundary between the two critical groundwater areas. Southwest of the fault, water levels in limestone are as much as 200 feet higher than those in silicic volcanics northeast of the fault, which indicates the fault is an effective barrier to groundwater movement. Results of an aquifer test in limestone southwest of the fault further indicate no hydraulic connection with the silicic volcanics aquifer northeast of the fault. Water levels in wells completed in limestone and silicic volcanics aquifers have declined 5 and 5.5 feet per year since 1977. Groundwater withdrawals in 1980 were about 60,000 acre-free from the silicic volcanics aquifer and, between 1977 and 1982, averaged about 5,300 acre-feet per year from the limestone aquifer. Annual recharge to the silicic volcanics aquifer is between about 10,000 and 26,000 acre-feet; recharge to the limestone aquifer is near 4,000 acre-feet. Limited water-quality data indicate the groundwater is chemically suitable for irrigation and domestic use. (USGS)

Water-Resources Investigations Report↗
USGS1987

Simulation of ground-water flow near the nuclear-fuel reprocessing facility at the Western New York Nuclear Service Center, Cattaraugus County, New York

A two-dimensional finite-difference model was developed to simulate groundwater flow in a surficial sand and gravel deposit underlying the nuclear fuel reprocessing facility at Western New York Nuclear Service Center near West Valley, N.Y. The sand and gravel deposit overlies a till plateau that abuts an upland area of siltstone and shale on its west side, and is bounded on the other three sides by deeply incised stream channels that drain to Buttermilk Creek, a tributary to Cattaraugus Creek. Radioactive materials are stored within the reprocessing plant and are also buried within a till deposit at the facility. Tritiated water is stored in a lagoon system near the plant and released under permit to Franks Creek, a tributary to Buttermilk Creek. Groundwater levels predicted by steady-state simulations closely matched those measured in 23 observation wells, with an average error of 0.5 meter. Simulated groundwater discharges to two stream channels and a subsurface drain were within 5% of recorded values. Steady-state simulations used an average annual recharge rate of 46 cm/yr; predicted evapotranspiration loss from the ground was 20 cm/yr. The lateral range in hydraulic conductivity obtained through model calibration was 0.6 to 10 m/day. Model simulations indicated that 33% of the groundwater discharged from the sand and gravel unit (2.6 L/sec) is lost by evapotranspiration, 3% (3.0 L/sec) flows to seepage faces at the periphery of the plateau, 20% (1.6 L/sec) discharges to stream channels that drain a large wetland area near the center of the plateau, and the remaining 8% (0.6 L/sec) discharges to a subsurface french drain and to a wastewater treatment system. Groundwater levels computed by a transient-state simulation of an annual climatic cycle, including seasonal variation in recharge and evapotranspiration, closely matched water levels measured in eight observation wells. The model predicted that the subsurface drain and the stream channel that drains the wetland would intercept most of the recharge originating near the reprocessing plant. (Lantz-PTT)

Water-Resources Investigations Report↗
USGS1988

Techniques for estimating the magnitude and frequency of floods in Minnesota

Log-Pearson type III flood-frequency analyses were made of annual series peak-flow records from 246 gaging stations on unregulated streams in Minnesota having watersheds ranging in area from 0.08 to 2,520 square miles. These flood discharges were related to watershed and climatic characteristics by using multiple-regression techniques. On the basis of this preliminary regression analysis of the frequency-analysis results, the data from these stations were grouped into four hydrologically distinct regions for the State. Regression analyses were performed on data from each region relating the 2-, 5-, 10-, 25-, 50-, and 100-year recurrence interval flood discharges to basin characteristics. The resulting regression equations, which may be used to estimate flood flows at ungaged sites, relate basin characteristics (contributing drainage area, main-channel slope, percent of basin covered by water, percent of basin covered by lakes, and mean annual runoff) to estimated flood flows. Different basin characteristics are significant for each of the four regions. Drainage area was found to be most significant and is included in all regional equations. Standard errors of estimate of the regression equations ranged from 33 to 60 percent.

Minnesota↗
USGS1996

Water resources of the Wind River Indian Reservation, Wyoming

Existing data were used in conjunction with onsite measurements to evaluate the water resources on the Wind River Indian Reservation, Wyoming. The reservation is located mainly in the Wind River drainage basin. Ground water is used for public- supply, domestic, agricultural, and industrial purposes, and potentially for irrigation. Deposits of Quaternary age provide water for domestic and public-supply uses. Median well yields from different types of Quaternary deposits ranged from 6 to 20 gallons per minute. The Wind River Formation of Tertiary age is a major source of water for domestic and public-supply uses; well yields ranged from 0.1 to 350 gallons per minute. For the Tensleep Sandstone and Madison Limestone of Paleozoic age, wells might yield as much as 1,000 gallons per minute. The dissolved-solids concentration of water from the Little Wind River and Popo Agie River flood-plain alluvium near mountains was generally less than 400 mg/L (milligrams per liter), but with increasing distance from mountains, the range was about 600 to about 750 mg/L. Dissolved-solids concentrations of water in the Wind River Formation ranged from 211 to 5,110 mg/L. Streams provide most water used for irrigation. Discharge records from streamflow-gaging stations indicate flow characteristics of streams on the reservation are extremely variable. Average annual runoff was 122 to 1,150 acre-feet per square mile on perennial streams with gaging stations. Near the mountains, most perennial streams had dissolved-solids concentrations less than 200 mg/L, and with increasing distance from the mountains, concentrations were about 400 to 600 mg/L.

Water-Resources Investigations Report↗
USGS2024

Marine heatwaves affect breeding, diet and population size but not body condition of a range-edge little penguin colony

Significant marine heatwaves (MHWs) developed along the Western Australian coast in 1999 and 2011. Despite ecosystem losses and the southwards occurrence of many tropical fish species during and after the extreme MHW in 2011, there have been few studies on the effects of this MHW on seabirds, and no biological impacts related to the 1999 MHW have been reported. Using data from 1986-2019, we investigated the impacts of these events on breeding outcomes, body condition, diet composition, population size and mortality of little penguins on Penguin Island, in the temperate waters off Western Australia. Breeding outcomes were negatively impacted by the MHWs but body condition was not. Diet composition changed after the MHW, with sandy sprat Hyperlophus vittatus , the penguins’ typical major prey component, replaced by scaly mackerel Sardinella lemuru , a tropical fish species. Using an open robust design analysis that accounts for imperfect capture probabilities and staggered annual arrival and departure dates, we found that the population decreased by 80% following the 2011 MHW. Finally, more penguins died from starvation or from novel protozoal parasitic infections in 2011 and 2012 that were potentially introduced with the changed diet. This research highlights that the temporal and spatial influence of MHWs on seabirds depends on several factors. Furthermore, the magnitude and direction of a prey species’ response can be very localised and have significant impacts on avian predators. There are no obvious ways to mediate climate effects, but perhaps measures taken to reduce any synergistic impacts on prey abundance, particularly during MHW events, could be effective.

Penguin Island↗
USGS2020

Precipitation, temperature, groundwater-level elevation, streamflow, and potential flood storage trends within the Brazos, Colorado, Big Cypress, Guadalupe, Neches, Sulphur, and Trinity River basins in Texas through 2017

The U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps of Engineers (USACE), analyzed streamflow trends and streamflow-related variables through 2017 in seven important water-supply basins to provide information that can help water managers with the USACE and river authorities make future water management decisions. The primary purpose of this report is to document trends in long-term streamflow data at 114 selected USGS streamflow-gaging stations and 36 simulated reservoir-inflow stations in 7 river basins primarily in Texas: Brazos, Colorado, Big Cypress, Guadalupe, Neches, Sulphur, and Trinity. In this report, trends were considered statistically significant if their p -values were less than or equal to 0.05 ( p -value ≤0.05). Streamflow data selected for temporal trend analyses included annual minimum streamflow, annual peak streamflow, and streamflow volume. Precipitation, air temperature, and groundwater-level-elevation data were analyzed for trends that may help to explain changes observed in the streamflow statistics. Basins were divided into sections along county lines for precipitation analyses. Streamflow volumes were analyzed for associations with potential flood storage. The potential flood storage, defined as the difference between maximum storage and normal storage, was computed for each dam from the National Inventory of Dams database and accumulated over time based on the completion date of the dam. Precipitation and air temperature trends were analyzed for each of the eight climate divisions (High Plains, Trans-Pecos, Low Rolling Hills, Edwards Plateau, North Central Texas, South Central Texas, East Texas, and Upper Coast). Results of precipitation trend analyses indicated moderate upward trends in the Upper Coast and East Texas Climate Divisions analyzed on an annual time step from 1900 through 2017. These two climate divisions are in the eastern and southeastern parts of the State, and they receive more mean annual precipitation (45.88 and 46.09 inches, respectively) than the other climate divisions. The results of air temperature analyses indicated upward trends in annual mean air temperature within all climate divisions, with a mean slope of 0.02 degree Fahrenheit per year, or 1 degree every 50 years. Within the Brazos River Basin, results of precipitation trend analyses on an annual time step indicated that precipitation amounts are most likely increasing in the lower and middle sections of the basin. Downward trends in annual streamflow and in the ratio of streamflow volume to precipitation volume were indicated at 7 of the 15 stations in the upper sections of the basin. The lower sections of the basin had mostly downward trends in annual minimum streamflow, whereas upward trends in annual minimum streamflow were indicated in the upper sections of the basin. Downward trends in annual peak streamflow were indicated at many of the stations in the upper sections of the basin. At the same seven stations in the upper sections of the basin where there were downward trends in annual streamflow, there were also downward trends in the ratio of streamflow volume to precipitation volume. The data from the same seven stations indicated negative associations between potential flood storage volume and annual streamflow volume and downward trends in the ratio of annual streamflow volume to potential flood storage volume. With the known addition of 13,006,394 acre-feet of potential flood storage between 1900 and 2010 in the subbasins analyzed, streamflow volumes have decreased in the upper sections of the Brazos River Basin. Within the Colorado River Basin, results of precipitation trend analyses on an annual time step indicated no trends in the basin. Downward trends in annual streamflow were indicated at 16 stations in the upper sections of the basin, whereas no trends in annual streamflow were indicated in the lower section of the basin. In the lower section of the basin, one station that was operated as a continuous streamflow-gaging station through 2017 had a downward trend in annual minimum streamflow, and another station (operated through 2007) had an upward trend in annual minimum streamflow. In the upper sections of the basin, data from seven stations indicated upward trends in annual minimum streamflow, and data from six stations indicated downward trends. Data from 18 stations in the upper sections of the basin indicated downward trends in annual peak streamflow. Thirteen of the 16 stations in the upper sections of the basin with data that indicated downward trends in annual streamflow also have data that indicated downward trends in the ratio of streamflow volume to precipitation volume. Data from the same 13 stations indicated negative associations between potential flood storage volume and annual streamflow volume and downward trends in the ratio of annual streamflow volume to potential flood storage volume. With the known addition of 7,193,147 acre-feet of potential flood storage between 1891 and 2014 in the subbasins analyzed, streamflow volumes have decreased in the upper sections of the Colorado River Basin. Within the Big Cypress Basin, results of precipitation trend analyses on annual, seasonal, and monthly time steps indicated almost no trends in the basin as defined in this report. However, the annual precipitation p -value only slightly exceeded the p -value threshold for a statistically significant trend. Given the upward trend in precipitation in the East Texas Climate Division, which includes the Big Cypress Basin, and the low p -value for annual precipitation within the basin, precipitation in the basin may be increasing over time. Two annual streamflow trends, one upward and one downward, were in the upper parts of the basin. Data from USGS streamflow-gaging station 07346000 Big Cypress Bayou near Jefferson, Texas, indicated an upward trend in annual minimum streamflow and a downward trend in annual peak streamflow. The station is immediately downstream from Lake O’ the Pines; presumably, minimums have increased because of regulated releases, and annual peaks have decreased because of storage from the lake for flood control. Despite the known addition of 2,737,154 acre-feet of potential flood storage between 1898 and 2011 in the subbasins analyzed, there have not been widespread reductions in streamflow volumes in the Big Cypress Basin, except for within the drainage area for the farthest upstream station on the main stem downstream from Mount Pleasant, Texas. Within the Guadalupe River Basin, results of precipitation trend analyses on an annual time step indicated an upward trend in the lower section of the basin, but no trends in annual streamflow were indicated in the lower section of the basin. In the upper section of the basin, data from 1 of the 13 stations indicated an upward trend in annual streamflow. Data from 6 of the 13 stations in the upper section of the basin indicated a trend in annual minimum streamflow with 4 upward and 2 downward trends. Data from 2 of the 13 stations in the upper section of the basin indicated downward trends in annual peak streamflow. Despite the known addition of 2,016,534 acre-feet of potential flood storage between 1849 and 2013 in the subbasins analyzed, streamflow volumes have not decreased in the Guadalupe River Basin. Within the Neches River Basin, results of precipitation trend analyses on an annual time step indicated upward trends in the basin. None of the data from stations analyzed in the Neches River Basin indicated annual trends in streamflow despite upward trends in annual precipitation within the basin. Data from 9 of the 19 stations analyzed in the basin indicated upward trends in annual minimum streamflow. Data from one of the simulated-inflow stations indicated a downward trend in annual minimum streamflow into Sam Rayburn Reservoir. Data from two stations indicated downward trends in annual peak streamflow, and data from one small subbasin indicated an upward trend in annual peak streamflow. Despite the known addition of 4,839,609 acre-feet of potential flood storage between 1888 and 2008 in the subbasins analyzed, there have not been widespread reductions in streamflow volumes in the Neches River Basin. Within the Sulphur River Basin, results of precipitation trend analyses on an annual time step indicated a moderate upward trend within the basin. Data from only one of the stations, the simulated inflow to Jim Chapman Lake, indicated an annual upward trend in streamflow despite an upward trend in annual precipitation throughout the basin. Data from three of the six stations in the Sulphur River Basin indicated upward trends in annual minimum streamflow, and data from one of the six stations indicated a downward trend in annual peak streamflow. Despite the known addition of 6,933,361 acre-feet of potential flood storage between 1904 and 2006 in the subbasins analyzed, streamflow volumes have not decreased in the Sulphur River Basin. Within the Trinity River Basin, results of precipitation trend analyses on an annual time step indicated upward trends in most sections of the basin. Data from 8 of the 36 stations analyzed for trends in annual streamflow indicated upward trends, and all 8 stations are in the upper sections of the basin. None of the data from stations in the lower sections of the basin indicated trends in annual streamflow. Data from 16 of the 36 stations indicated upward trends in annual minimum streamflow. Upward trends in annual minimum streamflow could be the result of managed reservoir releases in combination with wastewater treatment plant releases in the large Dallas-Fort Worth metroplex in the upper sections of the basin. All the trends in annual peak streamflow were in the sections of the basin that include the Dallas-Fort Worth metroplex. Data from two stations, one USGS streamflow-gaging station and one simulated-inflow station, indicated upward trends in annual peak streamflow, and data from one streamflow-gaging station indicated a downward trend in annual peak streamflow. Of the basins included in this study, the Trinity River Basin has the second largest amount of potential flood storage of 8,947,349 acre-feet from dams added between 1890 and 2013. Eleven stations in the Trinity River Basin had positive associations between potential flood storage volume and annual streamflow volume, indicating that annual streamflow increases as potential flood storage increases. Data from 7 of the 11 stations also indicated upward trends in annual streamflow. The positive associations may be the result of increases in minimum streamflow, which could be the result of any combination of managed reservoir releases, wastewater treatment plant releases, or increased runoff from urbanized areas, particularly in the urbanized area of the Dallas-Fort Worth metroplex.

Texas↗
USGS2006

Evaluation of the ground-water flow model for northern Utah Valley, Utah, updated to conditions through 2002

This report evaluates the performance of a numerical model of the ground-water system in northern Utah Valley, Utah, that originally simulated ground-water conditions during 1947-1980 and was updated to include conditions estimated for 1981-2002. Estimates of annual recharge to the ground-water system and discharge from wells in the area were added to the original ground-water flow model of the area. The files used in the original transient-state model of the ground-water flow system in northern Utah Valley were imported into MODFLOW-96, an updated version of MODFLOW. The main model input files modified as part of this effort were the well and recharge files. Discharge from pumping wells in northern Utah Valley was estimated on an annual basis for 1981-2002. Although the amount of average annual withdrawals from wells has not changed much since the previous study, there have been changes in the distribution of well discharge in the area. Discharge estimates for flowing wells during 1981-2002 were assumed to be the same as those used in the last stress period of the original model because of a lack of new data. Variations in annual recharge were assumed to be proportional to changes in total surface-water inflow to northern Utah Valley. Recharge specified in the model during the additional stress periods varied from 255,000 acre-feet in 1986 to 137,000 acre-feet in 1992. The ability of the updated transient-state model to match hydrologic conditions determined for 1981-2002 was evaluated by comparing water-level changes measured in wells to those computed by the model. Water-level measurements made in February, March, or April were available for 39 wells in the modeled area during all or part of 1981-2003. In most cases, the magnitude and direction of annual water-level change from 1981 to 2002 simulated by the updated model reasonably matched the measured change. The greater-than-normal precipitation that occurred during 1982-84 resulted in period-of-record high water levels measured in many of the observation wells in March 1984. The model-computed water levels at the end of 1982-84 also are among the highest for the period. Both measured and computed water levels decreased during the period representing ground-water conditions from 1999 to 2002. Precipitation was less than normal during 1999-2002. The ability of the model to adequately simulate climatic extremes such as the wetter-than-normal conditions of 1982-84 and the drier-than-normal conditions of 1999-2002 indicates that the annual variation of recharge to the ground-water system based on streamflow entering the valley, which in turn is primarily dependent upon precipitation, is appropriate but can be improved. The updated transient-state model of the ground-water system in northern Utah Valley can be improved by making revisions on the basis of currently available data and information.

Utah↗
USGS1964

Hydrologic studies of small watersheds, Honey Creek basin, Collin and Grayson Counties, Texas, 1953-1959

This report presents the results of an investigation into the effects of floodwaterretarding structures in the 39 square miles of the Honey Creek basin above the stream-gaging station near McKinney, during the period October 1952 to September 1959. The number of such structures in the study area was increased from 2 to 12 during the investigation. Data were collected which permit computation of basin and watershed precipitation, inflow to and outflow from each floodwater-retarding structure, evaporation and seepage from each pool, and a continuous record of discharge from the entire study area. Transpiration was not evaluated, but in the water-budget summary it is included in the item "pool consumption", together with evaporation and seepage. During the 7-year study period, the annual inflow to the gaged pools ranged from 1.34 to 26.50 inches and averaged 7.39 inches, of which 0.73 inch was direct rainfall on the pool surface. The annual pool consumption ranged only from 1.33 to 1.85 inches, and averaged 1.62 inches. These results indicate that in a year of substantial runoff the floodwater-retarding structures would have only a minor effect on downstream water yield, but in a year of low runoff the structures would have a marked effect on downstream water yield. The effect on the flood regimen at a downstream point because of floodwaterretarding structures in the headwaters will vary with the amount and intensity of the precipitation and with antecedent conditions. The beneficial effects of the structures on Honey Creek during the floods of April and May 1957 is illustrative. During the period April 19 to May 31, 1957, the total volume of inflow to the floodwater-retarding structures was equivalent to 4.3 times the combined capacities of the pools from an average basin rainfall of 30.31 inches. The retarding effects of the structures limited the flooding on Honey Creek at the gage to minor flooding on only five occasions during that period.

Texas↗
USGS2009

Analysis of Dissolved Selenium Loading from Surface Water and Groundwater to Sweitzer Lake, Colorado, 2006-07

Elevated selenium concentrations in streams are a water-quality concern in western Colorado. Sweitzer Lake was placed on the State 303(d) list as impaired with respect to dissolved selenium. In Colorado, the Water Quality Control Division of the Colorado Department of Public Health and Environment is required to develop total maximum daily loads of selenium for the 303(d) list segments. The U.S. Geological survey, in cooperation with the Colorado Department of Public Health and Environment, summarized selenium loading from surface water and ground water to Sweitzer Lake to support the total maximum daily loads development process. Surface-water and groundwater data were collected to quantify selenium concentrations and loads to Sweitzer Lake from October 2006 to October 2007. These data were used to determine the amount of selenium load (pounds annually) that would need to be reduced for the contributing sources (surface water and groundwater) to meet the State chronic aquatic-life standard of 4.6 micrograms per liter for dissolved selenium, herein referred to as 'a load reduction.' Selenium concentration data were also compared to the State acute aquatic-life standard of 18.4 micrograms per liter for dissolved selenium. Both surface-water and groundwater-quality samples collected during this study were found to exceed the chronic standard. Surface-water quantity and quality data were collected at Garnet Canal Diversion and Diversion Drain. Groundwater flux data were collected at 10 seepage-meter sires in Sweitzer Lake, and groundwater-quality data were collected at a groundwater seep and inferred from a January 2007 sample collected at Garnet Canal Diversion. Selenium concentrations and loads were greater at Garnet Canal Diversion than those observed at Diversion Drain. Approximately one-third of Garnet Canal Diversion-s Streamflow originates from Loutzenhizer Arroyo. Selenium concentrations observed during previous studies at Loutzenhizer Arroyo indicate high selenium concentrations and high selenium loads. All selenium concentrations in samples from Garnet Canal Diversion were greater than the chronic standard and were less that the acute standard during the irrigation season. Seventy-three percent of the annual selenium load at Garnet Canal Diversion would need to be reduced in order to meet the chronic standard. All daily mean selenium concentrations and selenium-concentration samples were greater than the chronic standard at Diversion Drain, but less than the acute standard during the irrigation season. Forty percent of the mean annual selenium loads at Diversion Drain would need to be reduced in order to meet the chronic standard. Estimated groundwater selenium loads and reductions of selenium loads to Sweitzer Lake were estimated using ranges of lake-bottom areas with positive groundwater flux and groundwater selenium concentrations. Estimated annual groundwater selenium load reductions ranged from 0.900 pound of the 1.17 pounds of annual load to 86.3 points of the 88.3 pounds of annual load for the selenium concentration scenarios over the range of lake-bottom areas. Groundwater selenium load and load reductions determined from this study identify the probably minimum and maximum values for these parameters. Further data collection and analysis could refine the range of groundwater selenium loads and load reductions.

Scientific Investigations Report↗
USGS2011

Water-quality conditions near the confluence of the Snake and Boise Rivers, Canyon County, Idaho

Total Maximum Daily Loads (TMDLs) have been established under authority of the Federal Clean Water Act for the Snake River-Hells Canyon reach, on the border of Idaho and Oregon, to improve water quality and preserve beneficial uses such as public consumption, recreation, and aquatic habitat. The TMDL sets targets for seasonal average and annual maximum concentrations of chlorophyll- a at 14 and 30 micrograms per liter, respectively. To attain these conditions, the maximum total phosphorus concentration at the mouth of the Boise River in Idaho, a tributary to the Snake River, has been set at 0.07 milligrams per liter. However, interactions among chlorophyll- a , nutrients, and other key water-quality parameters that may affect beneficial uses in the Snake and Boise Rivers are unknown. In addition, contributions of nutrients and chlorophyll- a loads from the Boise River to the Snake River have not been fully characterized. To evaluate seasonal trends and relations among nutrients and other water-quality parameters in the Boise and Snake Rivers, a comprehensive monitoring program was conducted near their confluence in water years (WY) 2009 and 2010. The study also provided information on the relative contribution of nutrient and sediment loads from the Boise River to the Snake River, which has an effect on water-quality conditions in downstream reservoirs. State and site-specific water-quality standards, in addition to those that relate to the Snake River-Hells Canyon TMDL, have been established to protect beneficial uses in both rivers. Measured water-quality conditions in WY2009 and WY2010 exceeded these targets at one or more sites for the following constituents: water temperature, total phosphorus concentrations, total phosphorus loads, dissolved oxygen concentration, pH, and chlorophyll- a concentrations (WY2009 only). All measured total phosphorus concentrations in the Boise River near Parma exceeded the seasonal target of 0.07 milligram per liter. Data collected during the study show seasonal differences in all measured parameters. In particular, surprisingly high concentrations of chlorophyll- a were measured at all three main study sites in winter and early spring, likely due to changes in algal populations. Discharge conditions and dissolved orthophosphorus concentrations are key drivers for chlorophyll- a on a seasonal and annual basis on the Snake River. Discharge conditions and upstream periphyton growth are most likely the key drivers for chlorophyll- a in the Boise River. Phytoplankton growth is not limited or driven by nutrient availability in the Boise River. Lower discharges and minimal substrate disturbance in WY2010 in comparison with WY2009 may have caused prolonged and increased periphyton and macrophyte growth and a reduced amount of sloughed algae in suspension in the summer of WY2010. Chlorophyll- a measured in samples commonly is used as an indicator of sestonic algae biomass, but chlorophyll- a concentrations and fluorescence may not be the most appropriate surrogates for algae growth, eutrophication, and associated effects on beneficial uses. Assessment of the effects of algae growth on beneficial uses should evaluate not only sestonic algae, but also benthic algae and macrophytes. Alternatively, continuous monitoring of dissolved oxygen detects the influence of aquatic plant respiration for all types of algae and macrophytes and is likely a more direct measure of effects on beneficial uses such as aquatic habitat. Most measured water-quality parameters in the Snake River were statistically different upstream and downstream of the confluence with the Boise River. Higher concentrations and loads were measured at the downstream site (Snake River at Nyssa) than the upstream site (Snake River near Adrian) for total phosphorus, dissolved orthophosphorus, total nitrogen, dissolved nitrite and nitrate, suspended sediment, and turbidity. Higher dissolved oxygen concentrations and pH were measured at the upstream site (Snake River near Adrian) than the downstream site (Snake River at Nyssa). Contributions from the Boise River measured at Parma do not constitute all of the increase in nutrient and sediment loads in the Snake River between the upstream and downstream sites. Surrogate models were developed using a combination of continuously monitored variables to estimate concentrations of nutrients and suspended sediment when samples were not possible. The surrogate models explained from 66 to 95 percent of the variability in nutrient and suspended sediment concentrations, depending on the site and model. Although the surrogate models could not always represent event-based changes in modeled parameters, they generally were successful in representing seasonal and annual patterns. Over a longer period, the surrogate models could be a useful tool for measuring compliance with state and site-specific water-quality standards and TMDL targets, for representing daily and seasonal variability in constituents, and for assessing effects of phosphorus reduction measures within the watershed.

Idaho↗
USGS2010

Hydrogeologic framework, groundwater movement, and water budget in the Chambers-Clover Creek watershed and vicinity, Pierce County, Washington

This report presents information used to characterize the groundwater-flow system in the Chambers-Clover Creek Watershed and vicinity, and includes descriptions of the geology and hydrogeologic framework; groundwater recharge and discharge; groundwater levels and flow directions; seasonal groundwater level fluctuations; interactions between aquifers and the surface-water system; and a water budget. The study area covers about 706 square miles in western Pierce County, Washington, and extends north to the Puyallup River, southwest to the Nisqually River, and is bounded on the south and east by foothills of the Cascade Range and on the west by Puget Sound. The area is underlain by a northwest-thickening sequence of unconsolidated glacial and interglacial deposits which overlie sedimentary and volcanic bedrock units that crop out in the foothills along the southern and southeastern margin of the study area. Geologic units were grouped into 11 hydrogeologic units consisting of aquifers, confining units, and an underlying bedrock unit. A surficial hydrogeologic unit map was developed and used with well information from 450 drillers’ logs to construct 6 hydrogeologic sections, and unit extent and thickness maps. Groundwater in unconsolidated glacial and interglacial aquifers generally flows to the northwest towards Puget Sound, and to the north and northeast towards the Puyallup River. These generalized flow patterns likely are complicated by the presence of low permeability confining units that separate discontinuous bodies of aquifer material and act as local groundwater-flow barriers. Water levels in wells completed in the unconsolidated hydrogeologic units show seasonal variations ranging from less than 1 to about 50 feet. The largest groundwater-level fluctuation (78 feet) observed during the monitoring period (March 2007–September 2008) was in a well completed in the bedrock unit. Synoptic streamflow measurements made in September 2007 and July 2008 indicated a total groundwater discharge to streams in the study area of 87,310 and 92,160 acre-feet per year, respectively. The synoptic streamflow measurements show a complex pattern of gains and losses to streamflows that varies throughout the study area, and appears to be influenced in places by local topography. Groundwater discharge occurs at numerous springs in the area and the total previously reported discharge of springs in the area is approximately 80,000 acre-feet per year. There are, in addition, many unmeasured springs and the total spring discharge in the area is unknown. The water-budget area (432 mi 2 located within the larger study area) received an annual average (September1, 2006, to August 31, 2008) of about 1,025,000 acre-ft or about 45 inches of precipitation a year. About 44 percent of precipitation enters the groundwater system as recharge. Almost one-half of this recharge (49 percent) discharges to the Puyallup and Nisqually Rivers and leaves the groundwater system as submarine groundwater discharge to Puget Sound. The remaining groundwater recharge discharges to streams (20 percent) and springs (18 percent) or is withdrawn from wells (13 percent)

Washington↗
USGS2014

Mean annual, seasonal, and monthly precipitation and runoff in Arkansas, 1951-2011

This report describes long-term annual, seasonal, and monthly means for precipitation and runoff in Arkansas for the period from 1951 through 2011. Precipitation means were estimated using data from the Parameter-elevation Regressions on Independent Slopes Model database; while total runoff, groundwater runoff, and surface runoff means were estimated using data from 123 active and inactive U.S. Geological Survey continuous-record streamflow-gaging stations located in Arkansas and surrounding States. Annual precipitation in Arkansas for the period from 1951 through 2011 had a mean of 49.8 inches. Of the six physiographic sections in Arkansas, the Ouachita Mountains had the largest mean annual precipitation at 53.0 inches, while the Springfield-Salem plateaus had the smallest mean annual precipitation at 45.5 inches. The mean annual total runoff for Arkansas was 17.8 inches. The Ouachita Mountains had the largest mean annual total runoff at 20.4 inches, while the Springfield-Salem plateaus had the smallest mean annual total runoff at 15.0 inches. Runoff is diminished during the dry season, which is attributed to increased losses from evapotranspiration, consumptive uses including irrigation, and increased withdrawals for public and private water supplies. The decline in runoff during the dry season is observed across the State in all physiographic sections. Spatial results for precipitation and runoff are presented in a series of maps that are available for download from the publication Web page in georeferenced raster formats.

Arkansas↗
USGS1982

Small-stream flood investigations in Minnesota, October 1958 to September 1980

An investigation of flood flows from small drainage basins in Minnesota is being made to aid in the design of bridges, culverts and other highway drainage structures. Results of the investigation provide peak-flow data on streams generally with drainage areas less than 200 square miles, placing particular emphasis on those with drainage areas lees than 10 square miles. Basin parameters being investigated for their effect on floods are drainage area, length of main stream, slope of main channel, basin altitude, forest cover, and storage area. All of the 187 gaging stations included in the report are equipped with crest-stage gages. In addition, 4 stations are equipped to record stage and precipitation continuously. The relative magnitude of flood flows for different hydrologic regions is shown in graphs that relate maximum discharge to drainage area. Station records contain location, drainage area, records available, type of gage, on-site structure elevations, bankfull stage, and annual maximum stage and discharge data. These data, with annual peak data from continuous-record stations, form the basis for statewide flood-frequency studies.

Minnesota↗
USGS2007

Mapping Evapotranspiration Units in the Basin and Range Carbonate-Rock Aquifer System, White Pine County, Nevada, and Adjacent Areas in Nevada and Utah

Accurate estimates of ground-water discharge are crucial in the development of a water budget for the Basin and Range carbonate-rock aquifer system study area. One common method used throughout the southwestern United States is to estimate ground-water discharge from evapotranspiration (ET). ET is a process by which water from the Earth's surface is transferred to the atmosphere. The volume of water lost to the atmosphere by ET can be computed as the product of the ET rate and the acreage of vegetation, open water, and moist soil through which ET occurs. The procedure used in the study groups areas of similar vegetation, water, and soil conditions into different ET units, assigns an average annual ET rate to each unit, and computes annual ET from each ET unit within the outer extent of potential areas of ground-water discharge. Data sets and the procedures used to delineate the ET-unit map used to estimate ground-water discharge from the study area and a qualitative assessment of the accuracy of the map are described in this report.

Scientific Investigations Report↗