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USGS2002

Simulation of hydrodynamics, temperature, and dissolved oxygen in Norfork Lake, Arkansas, 1994-1995

Outflow from Norfork Lake and other White River reservoirs support a cold-water trout fishery of significant economic yield in north-central Arkansas and south-central Missouri. The Arkansas Game and Fish Commission has requested an increase in existing minimum flows through the Norfork Lake dam to increase the amount of fishable waters downstream. Information is needed to assess the impact of increased minimum flows on temperature and dissolved-oxygen concentrations of reservoir water and the outflow. A two-dimensional, laterally averaged, hydrodynamic, temperature, and dissolved-oxygen model was developed and calibrated for Norfork Lake, located on the Arkansas-Missouri State line. The model simulates water-surface elevation, heat transport, and dissolved-oxygen dynamics. The model was developed to assess the impacts of proposed increases in minimum flow from 1.6 cubic meter per second (the existing minimum flow) to 8.5 cubic meters per second (the increased minimum flow). Simulations included assessing the impact of (1) increased minimum flows and (2) increased minimum flows with increased water-surface elevation of 1.1 meter in Norfork Lake on outflow temperatures and dissolved-oxygen concentrations. The increased minimum flow simulation (without increasing initial water-surface elevation) appeared to increase the water temperature and decrease dissolved-oxygen concentration in the outflow. Conversely, the increased minimum flow and initial increase in water-surface elevation (1.1 meter) simulation appeared to decrease outflow water temperature and increase dissolved-oxygen concentration through time. However, results from both scenarios for water temperature and dissolved-oxygen concentration were within the boundaries or similar to the error between measured and simulated water column profile values.

Arkansas↗
USGS2002

Near-real-time simulation and internet-based delivery of forecast-flood inundation maps using two-dimensional hydraulic modeling--A pilot study for the Snoqualmie River, Washington

A system of numerical hydraulic modeling, geographic information system processing, and Internet map serving, supported by new data sources and application automation, was developed that generates inundation maps for forecast floods in near real time and makes them available through the Internet. Forecasts for flooding are generated by the National Weather Service (NWS) River Forecast Center (RFC); these forecasts are retrieved automatically by the system and prepared for input to a hydraulic model. The model, TrimR2D, is a new, robust, two-dimensional model capable of simulating wide varieties of discharge hydrographs and relatively long stream reaches. TrimR2D was calibrated for a 28-kilometer reach of the Snoqualmie River in Washington State, and is used to estimate flood extent, depth, arrival time, and peak time for the RFC forecast. The results of the model are processed automatically by a Geographic Information System (GIS) into maps of flood extent, depth, and arrival and peak times. These maps subsequently are processed into formats acceptable by an Internet map server (IMS). The IMS application is a user-friendly interface to access the maps over the Internet; it allows users to select what information they wish to see presented and allows the authors to define scale-dependent availability of map layers and their symbology (appearance of map features). For example, the IMS presents a background of a digital USGS 1:100,000-scale quadrangle at smaller scales, and automatically switches to an ortho-rectified aerial photograph (a digital photograph that has camera angle and tilt distortions removed) at larger scales so viewers can see ground features that help them identify their area of interest more effectively. For the user, the option exists to select either background at any scale. Similar options are provided for both the map creator and the viewer for the various flood maps. This combination of a robust model, emerging IMS software, and application interface programming should allow the technology developed in the pilot study to be applied to other river systems where NWS forecasts are provided routinely.

Water-Resources Investigations Report↗
USGS2003

Extent of areal inundation of riverine wetlands along Cypress Creek and the Peace, Alafia, North Prong Alafia, and South Prong Alafia Rivers, west-central Florida

Riverine and palustrine system wetlands are a major ecological component of river basins in west-central Florida. Healthy wetlands are dependent upon the frequency and duration of periodic flooding or inundation. This report assesses the extent, area, depth, frequency, and duration of periodic flooding and the effects of potential surface-water withdrawals on the wetlands along Cypress Creek and the Peace, Alafia, North Prong Alafia, and South Prong Alafia Rivers. Results of the study were derived from step-backwater analysis performed at each of the rivers using the U.S. Army Corps of Engineers Hydrologic Engineering Center-River Analysis System (HEC-RAS) one-dimensional model. The step-backwater analysis was performed using selected daily mean discharges at the 10th, 50th, 70th, 80th, 90th, 98th, 99.5th, and 99.9th percentiles to compute extent of areal inundation, area of inundation, and hydraulic depth to assess the net reduction of areal inundation if 10 percent of the total river flow were diverted for potential withdrawals. The extent of areal inundation is determined by cross-sectional topography and the degree to which the channel is incised. Areal inundation occurs along the broad, low relief of the Cypress Creek floodplain during all selected discharge percentiles. However, areal inundation of the Peace and Alafia Rivers floodplains, which generally have deeply incised channels, occurs at or above discharges at the 80th percentile. The greatest area of inundation along the three rivers generally occurs between the 90th and 98th percentile discharges. The decrease in inundated area resulting from a potential 10-percent withdrawal in discharge ranged as follows: Cypress Creek, 22 to 395 acres (1.7 to 8.4 percent); Peace River, 17 to 1,900 acres (2.1 to 13.6 percent); Alafia River, 1 to 90 acres (1 to 19.6 percent); North Prong Alafia River, 1 to 46 acres (0.7 to 23.4 percent); and South Prong Alafia River, 1 to 75 acres (1.5 to 13.4 percent).

Water-Resources Investigations Report↗
USGS2003

Trends in nitrogen concentration and nitrogen loads entering the South Shore Estuary Reserve from streams and ground-water discharge in Nassau and Suffolk counties, Long Island, New York, 1952–97

The 13 major south-shore streams in Nassau and Suffolk Counties, Long Island, New York with adequate long-term (1971-97) water-quality records, and 192 south-shore wells with sufficient water-quality data, were selected for analysis of geographic, seasonal, and long-term trends in nitrogen concentration. Annual total nitrogen loads transported to the South Shore Estuary Reserve (SSER) from 11 of these streams were calculated using long-term discharge records. Nitrogen loads from shallow and deep ground water also were calculated using simulated ground-water discharge of 1968-83 hydrologic conditions. Long-term declines in stream discharge occurred in East Meadow Brook, Bellmore Creek and Massapequa Creek in response to extensive sewering in Nassau County. The smallest longterm annual discharge to the SSER was from the westernmost stream, Pines Brook, which is in an area in which the water table has been lowered by sewers since 1952. The three largest average annual discharges to the SSER were from the Connetquot River, Carlls River, and Carmans River in Suffolk County; the discharges from each of these streams were at least twice those of the other streams considered in this study. Total nitrogen concentrations in streams show a geographic trend with a general eastward increase in median total nitrogen concentration in Nassau County and a decreasing trend from Massapequa Creek eastward into Suffolk County. Total nitrogen concentrations in streams generally are lowest during summer and highest in winter as a result of seasonal fluctuations in chemical reactions and biological activity. The greatest seasonal difference in median total nitrogen concentration was at Carlls River with values of 3.4 and 4.2 mg/L (milligrams per liter) as N during summer (April through September) and winter (October through March), respectively. Streams affected by the completion of sewer districts show long-term (1971-97) trends of decreasing total nitrogen concentration and streams showing an increase in total nitrogen concentration are in unsewered areas with increased urbanization. Discharges from shallow ground water (upper glacial aquifer) and deep ground water (upper part of Magothy aquifer) were simulated from a ground-water-flow model calibrated to steadystate (1968-83) conditions. Simulated discharges from shallow-ground-water system in Nassau County were 10,700 Mgal/yr (million gallons per year) or 40,500,000 m 3 /yr (cubic meters per year), and those from Suffolk County were 52,300 Mgal/yr or 198,000,000 m 3 /yr. Discharges from deep-ground-water system in Nassau County were 4,900 Mgal/yr or 18,500,000 m 3 /yr, and those in Suffolk County were 12,700 Mgal/yr or 48,200,000 m 3 /yr. Ground-water concentrations of nitrogen decrease with depth and from west to east. The shallow ground water median nitrogen concentration for each county was determined using 1,155 samples collected at 167 shallow wells (125 feet deep or less) within 1 mile of the shore. The deep ground water median nitrate concentration (nitrate represented almost all of the total nitrogen) for each county was determined using 112 samples collected at 25 deep wells (greater than 125 feet deep) within 1 mile of the shore. The median nitrogen concentration for the shallow and median nitrate concentration for the deep ground water in Nassau County were 3.85 and 0.15 mg/L as N, during 1952–97; the corresponding concentrations for Suffolk County were 1.74 and <0.10 (less than 0.10) mg/L as N, during 1952–97. Nitrogen loads discharged from streams to the SSER for each year during 1972–97 were calculated as the annual total nitrogen concentration multiplied by the annual discharge. These values were calculated only for the seven streams for which sufficient data were available. The largest long-term (1972–97) average annual nitrogen load from Carlls River was 104 ton/yr or 94,300 kg/yr—about twice that of Connetquot River (54 ton/yr or 48,900 kg/yr) and over three times that of Carmans River (33 ton/yr or 29,900 kg/yr). The smallest annual mean nitrogen load was from Pines Brook, which has the lowest annual mean discharge of all streams analyzed. The nitrogen load carried to the SSER by ground-water discharge in shallow-ground-water system in Nassau and Suffolk Counties was calculated as the simulated discharge for each county multiplied by the respective median nitrogen concentration, and loads from deep-ground-water system were calculated as the simulated discharge for each county multiplied by the respective median nitrate concentration. All discharges were obtained from the U.S. Geological Survey's Long Island ground-water-flow model. The resultant nitrogen loads discharged to the SSER from shallow ground water were 172 ton/yr (156,000 kg/yr) from Nassau County and 380 ton/yr (345,000 kg/yr) from Suffolk County; equaling 552 ton/yr entering the SSER. Those from deep ground water were 3 ton/yr (2,700 kg/yr) from Nassau County and <0.5 ton/yr (480 kg/yr) from Suffolk County; equaling about 3.5 ton/yr entering the SSER. The sum of both stream loads and groundwater loads results in the total load to the SSER. The largest calculated total nitrogen load entering the SSER from both streams and ground water occurred in 1979 with a total load of 1,260 ton/yr (1,140,000 kg/yr). The smallest calculated nitrogen load entering the SSER occurred in 1995 with a total load of 725 ton/yr (658,000 kg/yr).

New York↗
USGS2003

Simulations of floodflows on the White River in the vicinity of U.S. Highway 79 near Clarendon, Arkansas

A two-dimensional finite-element surface-water model was used to study the effects of the proposed modification to the U.S. Highway 79 corridor on flooding on the White River near Clarendon, Arkansas. The effects of floodflows were simulated for the following scenarios: existing, natural, and four proposed bridging alternatives. All of the scenarios were modeled with floods having the 5- and 100-year recurrence intervals (115,100 and 216,000 cubic feet per second). The simulated existing conditions included a 3,200-foot White River bridge located on the east side of the study area near Clarendon, Arkansas; a 3,700-foot First Old River bridge located 0.5 mile west of the White River bridge opening; and a 1,430-foot Roc Roe Bayou bridge located 1.6 mile west of the First Old River bridge. The simulated hypothetical natural conditions involved removing the U.S. Highway 79 and the Union Pacific Railroad embankments along the entire length of the flood plain. The primary purpose of model simulations for natural conditions was to calculate backwater data for the existing and proposed conditions. The four simulated hypothetical proposed alternatives involved a 1.8-mile White River bridge located on the east side of the study area near Clarendon, Arkansas, either a 1,400-foot relief bridge (Alternative 1) or a 1,545 relief bridge (Alternatives 2-4) located 0.25 mile west of the White River bridge opening, and three different Roc Roe Bayou bridge openings ranging from 1,540-3,475 feet in length located 0.9 mile west of the relief bridge (Alternatives 1-4). Simulation of the 5-year floodflow for the existing bridge openings indicates that about 57 percent (65,600 cubic feet per second) of flow was conveyed by the White River bridge, about 26 percent (29,900 cubic feet per second) by the First Old River bridge, and about 17 percent (19,600 cubic feet per second) by the Roc Roe Bayou bridge. Maximum depth-averaged point velocities for the White River, First Old River, and Roc Roe Bayou bridges were 3.6, 1.6, and 3.3 feet per second, respectively. For the 100-year floodflow, the simulation indicates that about 56 percent (123,100 cubic feet per second) of flow was conveyed by the White River bridge, about 26 percent (56,200 cubic feet per second) by the First Old River bridge, and about 19 percent (41,000 cubic feet per second) by the Roc Roe Bayou bridge. The maximum depth-averaged point velocities for the White River, First Old River, and Roc Roe Bayou bridges were 4.2, 2.2, and 4.1 feet per second, respectively. Simulation of the 5-year floodflow for the proposed U.S. Highway 79 alignment alternatives indicates that 76-78 percent (87,100-89,900 cubic feet per second) of the flow was conveyed by the proposed White River bridge, 6-7 percent (7,000-7,500 cubic feet per second) by the proposed relief bridge, and 13-16 percent (14,600-18,600 cubic feet per second) by the proposed Roc Roe Bayou bridge. For the 100-year floodflow, simulations predicted that 70-72 percent (151,200-155,600 cubic feet per second) of the flow was conveyed by the proposed White River bridge, 9-10 percent (19,800-20,700 cubic feet per second) by the proposed relief bridge, and 14-20 percent (30,700-43,000 cubic feet per second) by the proposed Roc Roe Bayou bridge.

Water-Resources Investigations Report↗
USGS2002

Possible sources of nitrate in ground water at swine licensed-managed feeding operations in Oklahoma, 2001

Samples collected and analyzed by the Oklahoma Department of Agriculture, Food, and Forestry from 1999 to 2001 determined that nitrate exceeded the U.S. Environmental Protection Agency maximum contaminant level for public drinking-water supplies of 10 milligrams per liter as nitrogen in 79 monitoring wells at 35 swine licensed-managed feeding operations (LMFO) in Oklahoma. The LMFOs are located in rural agricultural settings where long-term agriculture has potentially affected the ground-water quality in some areas. Land use prior to the construction of the LMFOs was assessed to evaluate the types of agricultural land use within a 500-meter radius of the sampled wells. Chemical and microbiological techniques were used to determine the possible sources of nitrate in water sampled from 10 wastewater lagoons and 79 wells. Samples were analyzed for dissolved major ions, dissolved trace elements, dissolved nutrients, nitrogen isotope ratios of nitrate and ammonia, wastewater organic compounds, and fecal coliform bacteria. Bacteria ribotyping analysis was done on selected samples to identify possible specific animal sources. A decision process was developed to identify the possible sources of nitrate. First, nitrogen isotope ratios were used to define sources as animal, mixed animal and fertilizer, or fertilizer. Second, wastewater organic compound detections, nitrogen-isotope ratios, fecal coliform bacteria detections, and ribotyping were used to refine the identification of possible sources as LFMO waste, fertilizer, or unidentified animal or mixtures of these sources. Additional evidence provided by ribotyping and wastewater organic compound data can, in some cases, specifically indicate the animal source. Detections of three or more wastewater organic compounds that are indicators of animal sources and detections of fecal coliform bacteria provided additional evidence of an animal source. LMFO waste was designated as a possible source of nitrate in water from 10 wells. The source of waste in water from five of those wells was determined through ribotyping, and the source of waste in water from the remaining five wells was determined by detections of three or more animal-waste compounds in the well samples. LMFO waste in the water from wells with unidentified animal source of nitrate does not indicate that LMFO waste was not the source, but indicated that multiple animal sources, including LMFO waste, may be the source of the nitrate.

Water-Resources Investigations Report↗
USGS2003

Simulations of Flooding on Pea River and Whitewater Creek in the Vicinity of the Proposed Elba Bypass at Elba, Alabama

A two-dimensional finite-element surface-water model was used to study the effects of proposed modifications to the State Highway 203 corridor (proposed Elba Bypass/relocated U.S. Highway 84) on water-surface elevations and flow distributions during flooding in the Pea River and Whitewater Creek Basins at Elba, Coffee County, Alabama. Flooding was first simulated for the March 17, 1990, flood, using the 1990 flood-plain conditions to calibrate the model to match measured data collected by the U.S. Geological Survey and the U.S. Army Corps of Engineers after the flood. After model calibration, the effects of flooding were simulated for four scenarios: (1) floods having the 50- and 100-year recurrence intervals for the existing flood-plain, bridge, highway, and levee conditions; (2) floods having the 50- and 100-year recurrence intervals for the existing flood-plain and levee conditions with the State Highway 203 embankment and bridge removed; (3) floods having the 50- and 100-year recurrence intervals for the existing flood-plain, bridge, and highway conditions with proposed modifications (elevating) to the levee; and (4) floods having the 50- and 100-year recurrence intervals for the proposed conditions reflecting the Elba Bypass and modified levee. The simulation of floodflow for the Pea River and Whitewater Creek flood of March 17, 1990, in the study reach compared closely to flood profile data obtained after the flood. The flood of March 17, 1990, had an estimated peak discharge of 58,000 cubic feet per second at the gage (just below the confluence) and was estimated to be between a 50-year and 100-year flood event. The estimated peak discharge for Pea River and Whitewater Creek was 40,000 and 42,000 cubic feet per second, respectively. Simulation of floodflows for the 50-year flood (51,400 cubic feet per second) at the gage for existing flood-plain, bridge, highway, and levee conditions indicated that about 31 percent of the peak flow was conveyed by the State Highway 203 bridge over Whitewater Creek, approximately 12 percent overtopped the State Highway 203 embankment, and about 57 percent was conveyed by the Pea River flood plain east of State Highway 125. For this simulation, flow from Pea River (2,380 cubic feet per second) overtopped State Highway 125 and crossed over into the Whitewater Creek flood plain north of State Highway 203, creating one common flood plain. The water-surface elevation estimated at the downstream side of the State Highway 203 bridge crossing Whitewater Creek was 202.82 feet. The girders for both the State Highway 203 and U.S. Highway 84 bridges were partially submerged, but U.S. Highway 84 was not overtopped. For the 100-year flood (63,500 cubic feet per second) at the gage, the simulation indicated that about 25 percent of the peak flow was conveyed by the State Highway 203 bridge over Whitewater Creek, approximately 24 percent overtopped the State Highway 203 embankment, and about 51 percent was conveyed by the Pea River flood plain east of State Highway 125. The existing levee adjacent to Whitewater Creek was overtopped by a flow of 3,200 cubic feet per second during the 100-year flood. For this simulation, flow from Pea River (6,710 cubic feet per second) overtopped State Highway 125 and crossed over into the Whitewater Creek flood plain north of State Highway 203. The water-surface elevation estimated at the downstream side of the State Highway 203 bridge crossing Whitewater Creek was 205.60 feet. The girders for both the State Highway 203 and U.S. Highway 84 bridges were partially submerged, and the west end of the U.S. Highway 84 bridge was overtopped. Simulation of floodflows for the 50-year flood at the gage for existing flood-plain and levee conditions, but with the State Highway 203 embankment and bridge removed, yielded a lower water-surface elevation (202.90 feet) upstream of this bridge than that computed for the existing conditions. For the 100-year flood, the simulation indi

Water-Resources Investigations Report↗
USGS2003

Hydrogeology and geochemistry of aquifers underlying the San Lorenzo and San Leandro areas of the East Bay Plain, Alameda County, California

The East Bay Plain, on the densely populated eastern shore of San Francisco Bay, contains an upper aquifer system to depths of 250 feet below land surface and an underlying lower aquifer system to depths of more than 650 feet. Injection and recovery of imported water has been proposed for deep aquifers at two sites within the lower aquifer system. Successful operation requires that the injected water be isolated from surface sources of poor-quality water during storage and recovery. Hydraulic, geochemical, and isotopic data were used to evaluate the isolation of deeper aquifers. Ground-water responses to tidal changes in the Bay suggest that thick clay layers present within these deposits effectively isolate the deeper aquifers in the northern part of the study area from overlying surficial deposits. These data also suggest that the areal extent of the shallow and deep aquifers beneath the Bay may be limited in the northern part of the study area. Despite its apparent hydraulic isolation, the lower aquifer system may be connected to the overlying upper aquifer system through the corroded and failed casings of abandoned wells. Water-level measurements in observation wells and downward flow measured in selected wells during nonpumped conditions suggest that water may flow through wells from the upper aquifer system into the lower aquifer system during nonpumped conditions. The chemistry of water from wells in the East Bay Plain ranges from fresh to saline; salinity is greater than seawater in shallow estuarine deposits near the Bay. Water from wells completed in the lower aquifer system has higher pH, higher sodium, chloride, and manganese concentrations, and lower calcium concentrations and alkalinity than does water from wells completed in the overlying upper aquifer system. Ground-water recharge temperatures derived from noble-gas data indicate that highly focused recharge processes from infiltration of winter streamflow and more diffuse recharge processes from infiltration of precipitation occur within the study area. However, recharge of imported water from leaking water-supply pipes, believed by previous investigators to be a large source of ground-water recharge, was not supported on the basis of oxygen-18 and deuterium data collected as part of this study. Based on tritium/helium-3 ages, most water in the upper aquifer system is relatively young and was recharged after 1952; however, water in the lower aquifer system is older and does not contain detectable tritium. Carbon-14 ages interpreted for water from wells in the lower aquifer system and underlying partly consolidated rocks range from 500 to more than 20,000 years before present. The greatest ages were in water from wells completed in the partly consolidated deposits that underlie the northern part of the study area. Ground water from wells in the lower aquifer system near the proposed Bayside injection/recovery site was recharged about 9,400 years before present and appears to be isolated from surface sources of recharge and ground-water contamination.

California↗
USGS2002

Water Quality of Camp Creek, Costello Creek, and Other Selected Streams on the South Side of Denali National Park and Preserve, Alaska

The Camp and Costello Creek watersheds are located on the south side of Denali National Park and Preserve. The Dunkle Mine, an abandoned coal mine, is located near the mouth of Camp Creek. Due to concern about runoff from the mine and its possible effects on the water quality and aquatic habitat of Camp Creek and its receiving stream, Costello Creek, these two streams were studied during the summer runoff months (June to September) in 1999 and 2000 as part of a cooperative study with the National Park Service. Since the south side of Denali National Park and Preserve is part of the U.S. Geological Survey?s National Water-Quality Assessment Cook Inlet Basin study unit, an additional part of this study included analysis of existing water-quality data at 23 sites located throughout the south side of Denali National Park and Preserve to compare with the water quality of Camp and Costello Creeks and to obtain a broader understanding of the water quality in this area of the Cook Inlet Basin. Analysis of water column, bed sediment, fish, invertebrate, and algae data indicate no effects on the water quality of Camp Creek from the Dunkle Mine. Although several organic compounds were found in the streambed of Camp Creek, all concentrations were below recommended levels for aquatic life and most of the concentrations were below the minimum reporting level of 50 ?g/kg. Trace element concentrations of arsenic, chromium, and nickel in the bed sediments of Camp Creek exceeded threshold effect concentrations (TEC), but concentrations of these trace elements were also exceeded in streambed sediments of Costello Creek above Camp Creek. Since the percent organic carbon in Camp Creek is relatively high, the toxicity quotient of 0.55 is only slightly above the threshold value of 0.5. Costello Creek has a relatively low organic carbon content and has a higher toxicity quotient of 1.19. Analysis of the water-quality data for other streams located in the south side of Denali National Park and Preserve indicate similarities to Camp Creek and Costello Creek. Most of the streams are calcium bicarbonate/calcium bicarbonate-sulfate type water with the exception of two streams that are calcium sulfate and magnesium sulfate type water. Trace element concentrations of arsenic, chromium, and nickel in the bed sediments of 9 streams exceeded the TEC or the probable effect concentration (PEC). Seven streams exceeded the threshold value of the toxicity quotient. Analysis of trace element concentrations in bed sediment and basin characteristics for 16 watersheds by cluster and discriminant analysis techniques indicated that the watersheds could be separated into two groups based on their basin characteristics.

Water-Resources Investigations Report↗
USGS2002

Simulation of the ground-water flow system at Naval Submarine Base Bangor and vicinity, Kitsap County, Washington

An evaluation of the interaction between ground-water flow on Naval Submarine Base Bangor and the regional-flow system shows that for selected alternatives of future ground-water pumping on and near the base, the risk is low that significant concentrations of on-base ground-water contamination will reach off-base public-supply wells and hypothetical wells southwest of the base. The risk is low even if worst-case conditions are considered ? no containment and remediation of on-base contamination. The evaluation also shows that future saltwater encroachment of aquifers below sea level may be possible, but this determination has considerable uncertainty associated with it. The potential effects on the ground-water flow system resulting from four hypothetical ground-water pumping alternatives were considered, including no change in 1995 pumping rates, doubling the rates, and 2020 rates estimated from population projections with two different pumping distributions. All but a continuation of 1995 pumping rates demonstrate the possibility of future saltwater encroachment in the Sea-level aquifer on Naval Submarine Base Bangor. The amount of time it would take for encroachment to occur is unknown. For all pumping alternatives, future saltwater encroachment in the Sea-level aquifer also may be possible along Puget Sound east and southeast of the base. Future saltwater encroachment in the Deep aquifer also may be possible throughout large parts of the study area. Projections of saltwater encroachment are least certain outside the boundaries of Naval Submarine Base Bangor. The potential effects of the ground-water pumping alternatives were evaluated by simulating the ground-water flow system with a three-dimensional uniform-density ground-water flow model. The model was calibrated by trial-and-error by minimizing differences between simulated and measured or estimated variables. These included water levels from prior to January 17, 1977 (termed 'predevelopment'), water-level drawdowns since predevelopment until April 15, 1995, ground-water discharge to streams in water year 1995, and residence times of ground water in different parts of the flow system that were estimated in a separate but related study. Large amounts of ground water were pumped from 1977 through 1980 from the Sea-level aquifer on Naval Submarine Base Bangor to enable the construction of an off-shore drydock. Records of the flow-system responses to the applied stresses were used to help calibrate the model. Errors in the calibrated model were significant. The poor agreement between simulated and measured values could be improved by making many local changes to hydraulic parameters but these changes were not supported by other data. Model errors may have resulted in errors in the simulated effects of ground-water pumping alternatives.

Water-Resources Investigations Report↗
USGS2002

Hydraulic properties of Mt. Simon aquifer, Prairie Island Indian community, southeastern Minnesota, 2001

An aquifer test of the Mt. Simon aquifer was conducted at the northern end of the Prairie Island Indian Com-munity, in cooperation with the Prairie Island Indian Community, September 10-11, 2001 to determine hydraulic properties. Two wells at the northern end of Prairie Island were used in the aquifer test. A production well, Water-Supply Well No. 3, completed in the Mt. Simon aquifer, was pumped for 24 hours at 1,530 gal/min. Draw-down and recovery water levels were measured in the pumped well and in an observation well located 458 ft from the pumped well that was open to the Mt. Simon aquifer. Recovery water levels were measured in both wells for 10 hours after pumping ceased at Water-Supply Well No. 3. Hantush and Theis methods type curves were fitted to the measured drawdown and recovery curves in the observation well. The results of matching the type curves to the measured data indicate that leakage is negligible from the overlying Eau Claire confining unit into the Mt. Simon aquifer. The transmissivity and storage coeffi-cients for the Mt. Simon aquifer, determined by both methods, are 3, 000 ft 2 /d and 3 x 10 -4 , respectively. The average hydraulic conductivity, assuming an aquifer thickness of 233 ft, is 10 ft/d.

Minnesota, Wisconsin↗
USGS2003

Simulation of Ground-Water Flow in the Irwin Basin Aquifer System, Fort Irwin National Training Center, California

Ground-water pumping in the Irwin Basin at Fort Irwin National Training Center, California resulted in water-level declines of about 30 feet from 1941 to 1996. Since 1992, artificial recharge from wastewater-effluent infiltration and irrigation-return flow has stabilized water levels, but there is concern that future water demands associated with expansion of the base may cause a resumption of water-level declines. To address these concerns, a ground-water flow model of the Irwin Basin was developed to help better understand the aquifer system, assess the long-term availability and quality of ground water, and evaluate ground-water conditions owing to current pumping and to plan for future water needs at the base. Historical data show that ground-water-level declines in the Irwin Basin between 1941 and 1996, caused the formation of a pumping depression near the pumped wells, and that recharge from the wastewater-treatment facility and disposal area caused the formation of a recharge mound. There have been two periods of water-level recovery in the Irwin Basin since the development of ground water in this basin; these periods coincide with a period of decreased pumpage from the basin and a period of increased recharge of water imported from the Bicycle Basin beginning in 1967 and from the Langford Basin beginning in 1992. Since 1992, artificial recharge has exceeded pumpage in the Irwin Basin and has stabilized water-level declines. A two-layer ground-water flow model was developed to help better understand the aquifer system, assess the long-term availability and quality of ground water, and evaluate ground-water conditions owing to current pumping and to plan for future water needs at the base. Boundary conditions, hydraulic conductivity, altitude of the bottom of the layers, vertical conductance, storage coefficient, recharge, and discharge were determined using existing geohydrologic data. Rates and distribution of recharge and discharge were determined from existing data and estimated when unavailable. Results of predictive simulations indicate that in 50 years, if artificial recharge continues to exceed pumpage in Irwin Basin, water levels could rise as much as 65 feet beneath the pumping depression, and as much as 10 feet in the wastewater-treatment facility and disposal area. Particle-tracking simulations were used to determine the pathlines and the traveltimes of water high in dissolved solids into the main pumping area. The pathlines of particles from two areas with high dissolved-solids concentrations show that in 50 years water from these areas almost reaches the nearest pumped well.

Water-Resources Investigations Report↗
USGS2002

Base (100-year) flood elevations for selected sites in Livingston County, Missouri

The primary criteria for community participation in the National Flood Insurance Program is the adoption and enforcement of floodplain management requirements that minimize the potential for flood damages to existing and proposed development in flood-hazard areas. This report provides base flood elevations (BFE) for a 100-year recurrence-interval flood for use in the management and regulation of 18 flood-hazard areas designated by the Federal Emergency Management Agency as approximate Zone A areas in Livingston County, Missouri. The one-dimensional surface-water flow models HEC-RAS and Water-Surface PROfile (WSPRO) were used to compute base (100-year) flood elevations for 18 Zone A sites. The HEC-RAS model was used at BFE sites 1 to 6, 9, 10, and 15 to 18. The WSPRO model was used at BFE sites 7, 8, and 11 to 14. The 18 sites are all located in Livingston County, Missouri, at U.S., State, or County road crossings, and the base flood elevation was determined at the upstream side of each crossing. The base (100-year) flood elevations for BFE 1, 2, and 3 on Shoal Creek at Dawn and Shoal Creek Drainage Ditch near Dawn are 701.0, 701.0, and 696.5 feet, respectively. The base (100-year) flood elevations for BFE 4 and 5 on Indian Branch near Sampsel and a tributary to Indian Branch near Sampsel are 711.7 and 755.4 feet, respectively. Site BFE 6 is located on Honey Creek near Farmersville and the base (100-year) flood elevation for this site is 730.8 feet. One site (BFE 7) is located on No Creek near Farmersville. The base (100-year) flood elevation for this site is 731.3 feet. Site BFE 8 is located on Crooked Creek near Chillicothe and the base (100-year) elevation is 716.4 feet. One site (BFE 9) is located on a tributary to Coon Creek at Chillicothe. The base (100-year) flood elevation for this site is 734.9 feet. Two sites (BFE 10 and 11) are located on Blackwell Branch at Chillicothe. The base (100-year) flood elevation for BFE 10 is 738.9 feet and for BFE 11 is 701.7 feet. The base (100-year) flood elevation for BFE 12 on Medicine Creek near Chula is 721.7 feet. Sites BFE 13 and 15 are on Muddy Creek and for BFE 14 is on Little Muddy Creek near Chula. The base (100-year) flood elevations for BFE 13 and 15 are 733.0 and 717.9 feet, respectively and for BFE 14 is 734.6 feet. Downstream from BFE 12 is site BFE 16 on Medicine Creek near Wheeling. The base (100-year) flood elevation for site BFE 16 is 686.1 feet. One site (BFE 17) is located on Campbell Creek near Bedford. The base (100-year) flood elevation at this site is 691.8 feet. Site BFE 18 is located on Towstring Creek near Hale. The base (100-year) flood elevation for site BFE 18 is 667.4 feet.

Missouri↗
USGS2002

Duration and Frequency Analysis of Lowland Flooding in Western Murfreesboro, Rutherford County, Tennessee, 1998-2000

Periodic flooding occurs at lowlands and sinkholes in and adjacent to the flood plain of the West Fork Stones River in the western part of Murfreesboro, Tennessee. Flooding in this area commonly occurs during the winter months from December through March. The maximum water level that flood waters will reach in a lowland or sinkhole is controlled by the elevation of the land surrounding the site or the overflow outlet. Maximum water levels, independent of overflow from the river, were estimated to be reached in lowlands and sinkholes in the study area every 1 to 4 years. Minor overflow from the West Fork Stones River (less than 1 foot in depth) into the study area has been estimated to occur every 10 to 20 years. Moderate overflow from the river (1 to 2 feet in depth) occurs on average every 20 to 50 years, while major river overflow (in excess of 2 feet in depth) can be expected every 50 years. Rainfall information for the area, and streamflow and water-level measurements from the West Fork Stones River, lowlands, sinkholes, caves, and wells in the study area were used to develop a flood-prone area map, independent of overflow from the river, for the study area. Water-level duration and frequency relations, independent of overflow from the river, were estimated for several lowlands, sinkholes, and wells in the study area. These relations are used to characterize flooding in lowland areas of western Murfreesboro, Rutherford County, Tennessee.

Water-Resources Investigations Report↗
USGS2003

Analytical and numerical simulation of the steady-state hydrologic effects of mining aggregate in hypothetical sand-and-gravel and fractured crystalline-rock aquifers

Analytical solutions and numerical models were used to predict the extent of steady-state drawdown caused by mining of aggregate below the water table in hypothetical sand-and-gravel and fractured crystalline-rock aquifers representative of hydrogeologic settings in the Front Range area of Colorado. Analytical solutions were used to predict the extent of drawdown under a wide range of hydrologic and mining conditions that assume aquifer homogeneity, isotropy, and infinite extent. Numerical ground-water flow models were used to estimate the extent of drawdown under conditions that consider heterogeneity, anisotropy, and hydrologic boundaries and to simulate complex or unusual conditions not readily simulated using analytical solutions. Analytical simulations indicated that the drawdown radius (or distance) of influence increased as horizontal hydraulic conductivity of the aquifer, mine penetration of the water table, and mine radius increased; radius of influence decreased as aquifer recharge increased. Sensitivity analysis of analytical simulations under intermediate conditions in sand-and-gravel and fractured crystalline-rock aquifers indicated that the drawdown radius of influence was most sensitive to mine penetration of the water table and least sensitive to mine radius. Radius of influence was equally sensitive to changes in horizontal hydraulic conductivity and recharge. Numerical simulations of pits in sand-and- gravel aquifers indicated that the area of influence in a vertically anisotropic sand-and-gravel aquifer of medium size was nearly identical to that in an isotropic aquifer of the same size. Simulated area of influence increased as aquifer size increased and aquifer boundaries were farther away from the pit, and simulated drawdown was greater near the pit when aquifer boundaries were close to the pit. Pits simulated as lined with slurry walls caused mounding to occur upgradient from the pits and drawdown to occur downgradient from the pits. Pits simulated as refilled with water and undergoing evaporative losses had little hydro- logic effect on the aquifer. Numerical sensitivity analyses for simulations of pits in sand-and-gravel aquifers indicated that simulated head was most sensitive to horizontal hydraulic conductivity and the hydraulic conductance of general-head boundaries in the models. Simulated head was less sensitive to riverbed conductance and recharge and relatively insensitive to vertical hydraulic conductivity. Numerical simulations of quarries in fractured crystalline-rock aquifers indicated that the area of influence in a horizontally anisotropic aquifer was elongated in the direction of higher horizontal hydraulic conductivity and shortened in the direction of lower horizontal hydraulic conductivity compared to area of influence in a homogeneous, isotropic aquifer. Area of influence was larger in an aquifer with ground-water flow in deep, low-permeability fractures than in a homogeneous, isotropic aquifer. Area of influence was larger for a quarry intersected by a hydraulically conductive fault zone and smaller for a quarry intersected by a low-conductivity fault zone. Numerical sensitivity analyses for simulations of quarries in fractured crystalline-rock aquifers indicated simulated head was most sensitive to variations in recharge and horizontal hydraulic conductivity, had little sensitivity to vertical hydraulic conductivity and drain cells used to simulate valleys, and was relatively insensitive to drain cells used to simulate the quarry.

Water-Resources Investigations Report↗
USGS2003

Response of fish communities to cropland density and natural environmental setting in the Eastern Highland Rim Ecoregion of the lower Tennessee River basin, Alabama and Tennessee, 1999

Response of fish communities to cropland density and natural environmental setting were evaluated at 20 streams in the Eastern Highland Rim Ecoregion of the lower Tennessee River Basin during the spring of 1999. Sites were selected to represent a gradient of cropland densities in basins draining about 30 to 100 square miles. Fish communities were sampled by using a combination of seining and electrofishing techniques. A total of 10,550 individual fish, representing 63 species and 15 families, were collected during the study and included the families Cyprinidae (minnows), 18 species; Percidae (perch and darters), 12 species; and Centrarchidae (sunfish), 12 species. Assessments of environmental characteristics, including instream and terrestrial data and land-cover data, were conducted for each site. Instream measurements, such as depth, velocity, substrate type, and embeddedness, were recorded at 3 points across 11 equidistant transects at each site. Terrestrial measurements, such as bank angle, canopy angle, and canopy closure percentage, were made along the stream bank and midchannel areas. Water-quality data collected included pH, dissolved oxygen, specific conductivity, water temperature, nutrients, and fecal-indicator bacteria. Substrate embeddedness was the only variable correlated with both cropland density and fish communities (as characterized by ordination scores and several community level metrics). Multivariate and nonparametric correlation techniques were used to evaluate fish-community responses to physical and chemical factors associated with a cropland-density gradient, where the gradient was defined as the percentage of the basin in row crops. Principal component analysis and correspondence analysis suggest that the Eastern Highland Rim Ecoregion is composed of three subgroups of sites based on inherent physical and biological differences. Data for the subgroup containing the largest number of sites were then re-analyzed, revealing that several environmental variables, such as nutrient concentrations, stream gradient, bankfull width, and substrate embeddedness, were related to cropland density; however, only a subset of those variables (substrate embeddedness, elevation, and streamflow) were related to fish communities. Results from this analysis suggest that although many water-quality and habitat variables are covariant with cropland density, most of the variables do not significantly affect fish-community composition; instead, fish communities primarily respond to the cumulative effects of sedimentation.

Water-Resources Investigations Report↗
USGS2003

Probability of detecting atrazine/desethyl-atrazine and elevated concentrations of nitrate in ground water in Colorado

Draft Federal regulations may require that each State develop a State Pesticide Management Plan for the herbicides atrazine, alachlor, metolachlor, and simazine. Maps were developed that the State of Colorado could use to predict the probability of detecting atrazine and desethyl-atrazine (a breakdown product of atrazine) in ground water in Colorado. These maps can be incorporated into the State Pesticide Management Plan and can help provide a sound hydrogeologic basis for atrazine management in Colorado. Maps showing the probability of detecting elevated nitrite plus nitrate as nitrogen (nitrate) concentrations in ground water in Colorado also were developed because nitrate is a contaminant of concern in many areas of Colorado. Maps showing the probability of detecting atrazine and(or) desethyl-atrazine (atrazine/DEA) at or greater than concentrations of 0.1 microgram per liter and nitrate concentrations in ground water greater than 5 milligrams per liter were developed as follows: (1) Ground-water quality data were overlaid with anthropogenic and hydrogeologic data using a geographic information system to produce a data set in which each well had corresponding data on atrazine use, fertilizer use, geology, hydrogeomorphic regions, land cover, precipitation, soils, and well construction. These data then were downloaded to a statistical software package for analysis by logistic regression. (2) Relations were observed between ground-water quality and the percentage of land-cover categories within circular regions (buffers) around wells. Several buffer sizes were evaluated; the buffer size that provided the strongest relation was selected for use in the logistic regression models. (3) Relations between concentrations of atrazine/DEA and nitrate in ground water and atrazine use, fertilizer use, geology, hydrogeomorphic regions, land cover, precipitation, soils, and well-construction data were evaluated, and several preliminary multivariate models with various combinations of independent variables were constructed. (4) The multivariate models that best predicted the presence of atrazine/DEA and elevated concentrations of nitrate in ground water were selected. (5) The accuracy of the multivariate models was confirmed by validating the models with an independent set of ground-water quality data. (6) The multivariate models were entered into a geographic information system and the probability maps were constructed.

Colorado↗