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At least 1,441 records · Page 80Linked to original sources
USGS1983

Computation of continuous records of streamflow

Records of continuous streamflow, published in the U.S. Geological Survey annual Water Data Reports for the States and territories, are computed from field data, mainly discharge measurements and recorder charts or tapes. This manual describes the computation procedures used and some details of related field operations. It was compiled mostly from unpublished Water Resource Division district manuals edited and supplemented to emphasize digital-recorder and associated computer use. Methods used primarily for graphic-recorder gaging stations and non-recording gages are also included. Reference is made to other publications for some of the more specialized or unusually complex procedures.

Techniques of Water-Resources Investigations↗
USGS1970

Fluvial sediment concepts

This report is the first of a series concerned with the measurement of and recording of information about fluvial sediment and with related environmental data needed to maintain and improve basic sediment knowledge. Concepts presented in this report involve (1) the physical characteristics of sediment which include aspects relative 'to weathering, soils, resistance to erosion, and particle size, (2) sediment erosion, transport, and deposition characteristics, which include aspects relative to fine sediment and overland flow, coarse sediment and streamflow, variations in stream sediment concentration, deposition, and denudation, (3) geomorphic considerations, which include aspects relative to the drainage basin, mass wasting, and channel properties, (4) economic aspects, and (5) data needs and program objectives to be attained through the use of several kinds of sediment records.

Techniques of Water-Resources Investigations↗
USGS1982

Flow model of the Hudson River estuary from Albany to New Hamburg, New York

A one-dimensional transient-flow-simulation model was developed to represent a 76-mile reach of the tidal Hudson River between Albany and New Hamburg. In this reach, the direction of flow reverses four times daily as a result of tidal influence; this produces complex current patterns and retards the rate at which the river can flush out pollutants. In the model, the reach studied is treated as two subreaches to incorporate differences in channel conditions and to simplify model calibration. This report includes all stage (water-level) and discharge data that were used to calibrate and verify the model and compares the model results with measured data. The model accurately simulated observed flows, but further calibration based upon additional flow measurements would improve simulation of the flow magnitude and phasing of the tide reversal under low-flow conditions. The model can be used to calculate instantaneous stage, velocity, and discharge for any location in the reach and can also be used to calculate net volume flux between tide reversals.

New York↗
USGS1990

A statistical processor for analyzing simulations made using the Modular Finite-Difference Ground-water Flow Model

Many hydrologic studies of ground-water systems are conducted using a digital computer model as an aid to understanding the flow system. One of the most commonly used ground-water modeling programs is the Modular Three-Dimensional Ground-water Flow Model (Modular Model) by McDonald and Harbaugh. This report presents a computer program to summarize the data input to and output from the Modular Model. The program is named the Modular Model Statistical Processor and is designed to be run following the Modular Model. The Modular Model Statistical Processor provides ground-water modelers with the capabilities to easily read data input to and output from the Modular Model, calculate descriptive statistics, generate histograms, perform logical tests using relational operators, calculate data arrays using arithmetic operators, and calculate flow vectors for use in a graphical-display program.

Water-Resources Investigations Report↗
USGS1998

A snapshot evaluation of stream environmental quality in the Little Conestoga Creek basin, Lancaster County, Pennsylvania

Many Lancaster County residents are interested in stream monitoring and habitat restoration to maintain or improve stream water quality and to keep contaminants from reaching ground water used to supply drinking water. To promote resident involvement and environmental stewardship, the Alliance for the Chesapeake Bay (ACB) and the U.S. Geological Survey (USGS) designed this “snapshot” study of water quality and aquatic-insect communities in the Little Conestoga Creek Basin. Citizen-based restoration programs can improve water quality at a local level; such efforts will ultimately improve the ecological integrity of the Lower Susquehanna River and the Chesapeake Bay. The Little Conestoga Creek Basin was studied for several reasons. It was felt the project should benefit Lancaster County residents because funding was provided by Pennsylvania Department of Environmental Protection funds generated in Lancaster County. The small drainage area size, 65.5 mi 2 (square miles), allowed resident involvement in the necessary training and the snapshot sampling plan. Also, a previous study within south-central Pennsylvania reported the highest nutrient yields entering the Susquehanna River are contributed by the Conestoga River and its tributary subbasins, and the Basin’s location within the Conestoga River watershed made it a potential contributor of high nutrient loads. However, few data had been collected in this Basin to characterize the water quality and aquatic-insect populations. Ongoing studies by a “stream team” from Lancaster County Academy and by students and staff at Millersville University did not fully document the level of stream impairment throughout the Basin.

Water-Resources Investigations Report↗
USGS2007

Geological assessment of cores from the Great Bay National Wildlife Refuge, New Hampshire

Geological sources of metals (especially arsenic and zinc) in aquifer bedrock were evaluated for their potential to contribute elevated values of metals to ground and surface waters in and around Rockingham County, New Hampshire. Ayotte and others (1999, 2003) had proposed that arsenic concentrations in ground water flowing through bedrock aquifers in eastern New England were elevated as a result of interaction with rocks. Specifically in southeastern New Hampshire, Montgomery and others (2003) established that nearly one-fifth of private bedrock wells had arsenic concentrations that exceed the U.S. Environmental Protection Agency (EPA) maximum contamination level for public water supplies. Two wells drilled in coastal New Hampshire were sited to intersect metasedimentary and metavolcanic rocks in the Great Bay National Wildlife Refuge. Bulk chemistry, mineralogy, and mineral chemistry data were obtained on representative samples of cores extracted from the two boreholes in the Kittery and Eliot Formations. The results of this study have established that the primary geologic source of arsenic in ground waters sampled from the two well sites was iron-sulfide minerals, predominantly arsenic-bearing pyrite and lesser amounts of base-metal-sulfide and sulfosalt minerals that contain appreciable arsenic, including arsenopyrite, tetrahedrite, and cobaltite. Secondary minerals containing arsenic are apparently limited to iron-oxyhydroxide minerals. The geologic source of zinc was sphalerite, typically cadmium-bearing, which occurs with pyrite in core samples. Zinc also occurred as a secondary mineral in carbonate form. Oxidation of sulfides leading to the liberation of acid, iron, arsenic, zinc, and other metals was most prevalent in open fractures and vuggy zones in core intervals containing zones of high transmissivity in the two units. The presence of significant calcite and lesser amounts of other acid-neutralizing carbonate and silicate minerals, acting as a natural buffer to reduce acidity, forced precipitation of iron-oxyhydroxide minerals and the removal of trace elements, including arsenic and lead, from ground waters in the refuge. Zinc may have remained in solution to a greater extent because of complexing with carbonate and its solubility in near-neutral ground and surface waters. The regional link between anomalously high arsenic contents in ground water and a bedrock source as established by Ayotte and others (1999, 2003) and Montgomery and others (2003) was confirmed by the presence of some arsenic-bearing minerals in rocks of the Kittery and Eliot Formations. The relatively low amounts of arsenic and metals in wells in the Great Bay National Wildlife Refuge as reported by Ayotte and others (U.S. Geological Survey Water Resources Data, 2005) were likely controlled by local geochemical environments in partially filled fractures, fissures, and permeable zones within the bedrock formations. Carbonate and silicate gangue minerals that line fractures, fissures, and permeable zones likely limited the movement of arsenic from bedrock to ground water. Sources other than the two geologic formations might have been required to account for anomalously high arsenic contents measured in private bedrock aquifer wells of Rockingham County.

New Hampshire↗
USGS2008

Summary of aquifer test data for Arkansas – 1940-2006

As demands on Arkansas's ground water continue to increase, decision-makers need all available information to ensure the sustainability of this important natural resource. From 1940 through 2006, the U.S. Geological Survey has conducted over 300 aquifer tests in Arkansas. Much of these data never have been published. This report presents the results from 206 of these aquifer tests from 21 different hydrogeologic units spread across 51 Arkansas counties. Ten of the hydrogeologic units are within the Atlantic Plain of Arkansas and consist mostly of unconsolidated and semi-consolidated deposits. The remaining 11 units are within the Interior Highlands consisting mainly of consolidated rock. Descriptive statistics are reported for each hydrologic unit with two or more tests, including the mean, minimum, median, maximum and standard deviation values for specific capacity, transmissivity, hydraulic conductivity, and storage coefficient. Hydraulic conductivity values for the major water-bearing hydrogeologic units are estimated because few conductivity values are recorded in the original records. Nearly all estimated hydraulic conductivity values agree with published hydraulic conductivity values based on the hydrogeologic unit material types. Similarly, because few specific capacity values were available in the original aquifer test records, specific capacity values are estimated for individual wells.

Arkansas↗
USGS2011

A method for estimating peak and time of peak streamflow from excess rainfall for 10- to 640-acre watersheds in the Houston, Texas, metropolitan area

Estimates of peak and time of peak streamflow for small watersheds (less than about 640 acres) in a suburban to urban, low-slope setting are needed for drainage design that is cost-effective and risk-mitigated. During 2007-10, the U.S. Geological Survey (USGS), in cooperation with the Harris County Flood Control District and the Texas Department of Transportation, developed a method to estimate peak and time of peak streamflow from excess rainfall for 10- to 640-acre watersheds in the Houston, Texas, metropolitan area. To develop the method, 24 watersheds in the study area with drainage areas less than about 3.5 square miles (2,240 acres) and with concomitant rainfall and runoff data were selected. The method is based on conjunctive analysis of rainfall and runoff data in the context of the unit hydrograph method and the rational method. For the unit hydrograph analysis, a gamma distribution model of unit hydrograph shape (a gamma unit hydrograph) was chosen and parameters estimated through matching of modeled peak and time of peak streamflow to observed values on a storm-by-storm basis. Watershed mean or watershed-specific values of peak and time to peak ("time to peak" is a parameter of the gamma unit hydrograph and is distinct from "time of peak") of the gamma unit hydrograph were computed. Two regression equations to estimate peak and time to peak of the gamma unit hydrograph that are based on watershed characteristics of drainage area and basin-development factor (BDF) were developed. For the rational method analysis, a lag time (time-R), volumetric runoff coefficient, and runoff coefficient were computed on a storm-by-storm basis. Watershed-specific values of these three metrics were computed. A regression equation to estimate time-R based on drainage area and BDF was developed. Overall arithmetic means of volumetric runoff coefficient (0.41 dimensionless) and runoff coefficient (0.25 dimensionless) for the 24 watersheds were used to express the rational method in terms of excess rainfall (the excess rational method). Both the unit hydrograph method and excess rational method are shown to provide similar estimates of peak and time of peak streamflow. The results from the two methods can be combined by using arithmetic means. A nomograph is provided that shows the respective relations between the arithmetic-mean peak and time of peak streamflow to drainage areas ranging from 10 to 640 acres. The nomograph also shows the respective relations for selected BDF ranging from undeveloped to fully developed conditions. The nomograph represents the peak streamflow for 1 inch of excess rainfall based on drainage area and BDF; the peak streamflow for design storms from the nomograph can be multiplied by the excess rainfall to estimate peak streamflow. Time of peak streamflow is readily obtained from the nomograph. Therefore, given excess rainfall values derived from watershed-loss models, which are beyond the scope of this report, the nomograph represents a method for estimating peak and time of peak streamflow for applicable watersheds in the Houston metropolitan area. Lastly, analysis of the relative influence of BDF on peak streamflow is provided, and the results indicate a 0:04log 10 cubic feet per second change of peak streamflow per positive unit of change in BDF. This relative change can be used to adjust peak streamflow from the method or other hydrologic methods for a given BDF to other BDF values; example computations are provided.

Texas↗
USGS2015

Estimation of unaltered daily mean streamflow at ungaged streams of New York, excluding Long Island, water years 1961-2010

The lakes, rivers, and streams of New York State provide an essential water resource for the State. The information provided by time series hydrologic data is essential to understanding ways to promote healthy instream ecology and to strengthen the scientific basis for sound water management decision making in New York. The U.S. Geological Survey, in cooperation with The Nature Conservancy and the New York State Energy Research and Development Authority, has developed the New York Streamflow Estimation Tool to estimate a daily mean hydrograph for the period from October 1, 1960, to September 30, 2010, at ungaged locations across the State. The New York Streamflow Estimation Tool produces a complete estimated daily mean time series from which daily flow statistics can be estimated. In addition, the New York Streamflow Estimation Tool provides a means for quantitative flow assessments at ungaged locations that can be used to address the objectives of the Clean Water Act—to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters. The New York Streamflow Estimation Tool uses data from the U.S. Geological Survey streamflow network for selected streamgages in New York (excluding Long Island) and surrounding States with shared hydrologic boundaries, and physical and climate basin characteristics to estimate the natural unaltered streamflow at ungaged stream locations. The unaltered streamflow is representative of flows that are minimally altered by regulation, diversion, or mining, and other anthropogenic activities. With the streamflow network data, flow-duration exceedance probability equations were developed to estimate unaltered streamflow exceedance probabilities at an ungaged location using a methodology that equates streamflow as a percentile from a flow-duration curve for a particular day at a hydrologically similar reference streamgage with streamflow as a percentile from the flow-duration curve for the same day at an ungaged location. The reference streamgage is selected using map correlation, a geostatistical method in which variogram models are developed that correlate streamflow at one streamgage with streamflows at all other locations in the study area. Regression equations used to predict 17 flow-duration exceedance probabilities were developed to estimate the flow-duration curves at ungaged locations for New York using geographic information system-derived basin characteristics. A graphical user interface, with an integrated spreadsheet summary report, has been developed to estimate and display the daily mean streamflows and statistics and to evaluate different water management or water withdrawal scenarios with the estimated monthly data. This package of regression equations, U.S. Geological Survey streamgage data, and spreadsheet application produces an interactive tool to estimate an unaltered daily streamflow hydrograph and streamflow statistics at ungaged sites in New York. Among other uses, the New York Streamflow Estimation Tool can assist water managers with permitting water withdrawals, implementing habitat protection, estimating contaminant loads, or determining the potential affect from chemical spills.

New York↗
USGS2015

Flood-inundation maps for Grand River, Red Cedar River, and Sycamore Creek near Lansing, Michigan

Digital flood-inundation maps for a total of 19.7 miles of the Grand River, the Red Cedar River, and Sycamore Creek were created by the U.S. Geological Survey (USGS) in cooperation with the City of Lansing, Michigan, and the U.S. Army Corps of Engineers. The flood-inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science Web site at http://water.usgs.gov/osw/flood_inundation/ , show estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at three USGS streamgages: Grand River at Lansing, MI (04113000), Red Cedar River at East Lansing, MI (04112500), and Sycamore Creek at Holt Road near Holt, MI (04112850). Near-real-time stages at these streamgages can be obtained on the Internet from the USGS National Water Information System at http://waterdata.usgs.gov/ or the National Weather Service (NWS) Advanced Hydrologic Prediction Service at http:/water.weather.gov/ahps/ , which also forecasts flood hydrographs at all of these sites. Each set of flood profiles was computed by means of a one-dimensional step-backwater model. Each model was calibrated to the current stage-discharge relation at each streamgage and to water levels determined with stage sensors (pressure transducers) temporarily deployed along each stream reach. The hydraulic model was used to compute a set of water-surface profiles for flood stages from nearly Action Stage to above Major Flood stage, as reported by the National Weather Service. The computed water-surface profiles were then used in combination with a Geographic Information System digital elevation model derived from light detection and ranging (lidar) data to delineate the approximate areas flooded at each water level. These maps, used in conjunction with real-time USGS streamgage data and NWS forecasting, provide critical information to emergency management personnel and the public. This information is used to plan flood response actions, such as evacuations and road closures, as well as aid in postflood recovery efforts.

Michigan↗
USGS2019

Revisions to suspended-sediment concentration, percent smaller than 0.063 millimeter, and instantaneous suspended-sediment discharge reported for a cooperative program between the U.S. Geological Survey and the U.S. Army Corps of Engineers in the lower Mississippi-Atchafalaya River Basin, October 1989 to February 2015

This report presents revised results for four parameters reported for suspended-sediment samples that were collected in the lower Mississippi-Atchafalaya River Basin as part of a cooperative program between the U.S. Army Corps of Engineers, Mississippi Valley Division, New Orleans District and the U.S. Geological Survey (USGS). The cooperative program has been active since 1973 at seven sites: two sites on the main stem of the Mississippi River, three sites on the Atchafalaya River, one site on the Old River Outflow Channel, and one site on the lower Red River above the confluence with the Old River Outflow Channel. The four parameters—suspended-sediment concentration, percent by mass of the sediment that passes through a 0.063-millimeter (US 230) sieve, instantaneous stream discharge, and instantaneous suspended-sediment discharge—reported for 2,895 samples have been modified to reflect the findings of a full review of the cooperative program, which was initiated by both agencies in January 2015. The revised results are for samples collected from October 1989 through February 2015. Ninety-four percent of the revised values for suspended-sediment concentration are lower than their corresponding original reported values, indicating that less suspended sediment moves through the lower Mississippi River system than was previously reported. For example, the median revised instantaneous suspended-sediment discharge at the Mississippi River at Tarbert Landing, Miss. (USGS station 07295100), was 315,000 short tons per day, compared to 378,000 short tons per day as originally reported. At the Atchafalaya River at Simmesport, La. (USGS station 07381490), the median revised suspended-sediment discharge was 105,000 short tons per day, compared to 143,000 short tons per day as originally reported. The systematic downward revision in instantaneous suspended-sediment discharge values was due to a systematic downward revision in the suspended fine (less than 0.063 millimeter) sediment concentration. The effect of the revision on the suspended-sand concentration and instantaneous suspended-sand discharge was weaker. Any model of sediment load or transport processes in the basin that uses data from the affected samples should be reevaluated on the basis of the revised results.

Lower Mississippi basin↗
USGS2024

Three-dimensional hydrogeologic framework model of the Russian River watershed, California

The Russian River watershed is in northern Sonoma County and southern Mendocino County, California, in the northern part of the California Coast Ranges. The Russian River serves as a supply for agricultural irrigation and for municipal, domestic, and commercial uses. Through a cooperative agreement with the California State Water Resources Control Board and Sonoma County Water Agency, the U.S. Geological Survey has completed studies to better understand the hydrogeologic system and develop numerical hydrologic modeling tools to evaluate and aid in managing groundwater resources. This report focuses on the development of a digital three-dimensional hydrogeologic framework model of the Russian River watershed for use in groundwater resource assessment and numerical models. The digital three-dimensional hydrogeologic framework model of the Russian River watershed portrays the altitude, thickness, and extent of five hydrogeologic units. These five hydrogeologic units include (1) a basement unit, (2) the Sonoma Volcanics, (3) a consolidated sedimentary rock unit, (4) an unconsolidated sediment unit, and (5) channel alluvium. Model input data were compiled from published geologic maps, interpreted well data, and a model of the top of basement derived from gravity data. These data were used to construct surfaces that represent the upper and lower subsurface boundaries of each hydrogeologic unit. Top surfaces were created for the five hydrogeologic units and then stacked in three dimensions to create a solid-volume digital model. The digital three-dimensional hydrogeologic framework model described in this report and the corresponding data represent the generalized geometry of the subsurface geologic units; the model reproduces the input geologic data with reasonable accuracy and is consistent with previously published subsurface conceptualizations of the region. The model indicates the overall geometry of the basement within the watershed and the spatial extent, altitude, and thickness of the basin-filling units. The hydrogeologic framework model is at a scale and resolution appropriate for use as the foundation for a numerical hydrologic model of the study area.

California↗
USGS2026

Updates to the Lake Washington Ship Canal and Ballard Locks model, Seattle, Washington, 2016–20

The Hiram M. Chittenden Locks (Ballard Locks or Locks) and Lake Washington Ship Canal connect freshwater Lake Washington with saline Shilshole Bay of Puget Sound. The Locks are operated by the U.S. Army Corps of Engineers (USACE) and serve commercial and recreational vessels. Anadromous salmonids migrate through the canal by making use of a fish ladder at the Locks. To help understand canal hydrodynamics, water temperature, and salinity, a two-dimensional model (CE-QUAL-W2) of the Locks and Lake Washington Ship Canal was constructed by WEST Consultants, Inc. In cooperation with USACE, the U.S. Geological Survey reviewed and updated this model and documentation. The review, published previously, recognized the strengths of the model and suggested some modifications and updates. This report documents these modifications, reports on sensitivity testing, describes model recalibration, and reports model results for calendar years 2016–20. Modeled water velocity was less than 0.2 meter per second at most sites and depths; velocity was greater nearer the Locks. Water age, which estimates residence time, was greatest during September and October. Water temperature was greater near-surface and cooler near the channel bottom at some times and locations. The model also simulated the inflow of lower-salinity waters from Lake Washington and the import of higher-salinity waters from the Locks.

Washington↗
USGS2000

Preliminary assessment of phosphorus transport in the Cheney Reservoir watershed, south-central Kansas, 1997-98

A 5-year assessment of water-quality conditions is being conducted in the 933-square-mile Cheney Reservoir watershed of south-central Kansas. Part of this assessment is to define source areas of phosphorus in the watershed and to quantify its transport into Cheney Reservoir. Concern exists for the quality of water in Cheney Reservoir particularly in regards to phosphorus because of its possible relation to algal blooms and subsequent taste and odor problems in treated drinking water from the reservoir. The purpose of this report is to present the results of a preliminary assessment of phosphorus transport during the first 2 complete years (1997-98) of data collection. Annual phosphorus loads and yields were estimated, using regression analysis, at six sampling sites in the Cheney Reservoir watershed. Phosphorus loads and yields for the entire watershed also were estimated. Estimated phosphorus loads at all sampling sites and two additional subwatershed areas were substantially larger in 1998 than in 1997, with a median increase of 68 percent. This increase was mostly the result of wetter conditions in 1998. Estimated mean annual phosphorus yields for 1997-98 (upstream from Cheney Reservoir) ranged from 0.131 to 0.371 pound per acre. Much of the between-site variability in yields was attributed to variability in water yield and does not represent substantial changes in land-use or land-management practices. On average, about 62 percent of the phosphorus load to the reservoir was retained in the reservoir. A mean annual phosphorus yield for 1997-98 for the entire Cheney Reservoir watershed was estimated at 0.20 pound per acre. This compares to mean annual phosphorus yields of 1.76 and 0.05 pounds per acre reported in previous reservoir watershed assessments conducted in the Hillsdale Lake watershed in eastern Kansas in 1996 and the Webster Reservoir watershed in western Kansas in 1998, respectively. However, because of some uncertainty of the representativeness of the Cheney Reservoir watershed mean annual yield for 1997-98, it is suggested that a detailed examination of reservoir bottom sediment and associated phosphorus might provide estimates of historical mean annual phosphorus loads to Cheney Reservoir and of yields from the watershed with which to compare results of the 1997-98 study.

Kansas↗
USGS2000

Vulnerability of ground water to contamination, Edwards Aquifer recharge zone, Bexar County, Texas, 1998

The Edwards aquifer, one of the most productive carbonate-rock aquifers in the Nation, is composed of the Kainer and Person Formations of the Edwards Group plus the overlying Georgetown Formation. Most recharge to the Edwards aquifer results from the percolation of streamflow loss and the infiltration of precipitation through porous parts of the recharge zone. Residential and commercial development is increasing, particularly in Bexar County in south-central Texas, atop the densely fractured and steeply faulted recharge zone. The increasing development has increased the vulnerability of ground water to contamination by spillage or leakage of waste materials, particularly fluids associated with urban runoff and (or) septic-tank leachate. This report describes a method of assessing the vulnerability of ground water to contamination in the Edwards aquifer recharge zone. The method is based on ratings of five natural features of the area: (1) hydraulic properties of outcropping hydrogeologic units; (2) presence or absence of faults; (3) presence or absence of caves and (or) sinkholes; (4) slope of land surface; and (5) permeability of soil. The sum of the ratings for the five natural features was used to develop a map showing the recharge zone's vulnerability to ground-water contamination.

Water-Resources Investigations Report↗
USGS1982

Water use in Wisconsin, 1979

This report summarizes the uses of water in Wisconsin for 1979, except aesthetics, navigation, and recreational use. The greatest single use of water, an instream use, was for hydroelectric power production. About 26 trillion gallons, or 93 percent, was used for this purpose. Of the other 7 percent where water is pumped to a different location, 81 percent (6 percent of all water use) was cooling water for thermoelectric powerplants. Withdrawals of surface water and ground water by public and private systems are for residential, industrial, commercial, irrigation, and stock uses.

Wisconsin↗
USGS1988

Water use for aquaculture in Minnesota, 1984

Aquaculture supports a large sportfishing industry in Minnesota. Licensed fish farms that hatch and (or) harvest minnows or gamefish are located throughout the State. The volume of water used in these operations can be expressed as the minimum capacity per pound of fish, total water consumed, total water dedicated to the farming operation, or total water withdrawn. In expressing water dedicated to the farming operation, the total surface area of water bodies dedicated to aquaculture in Minnesota in 1984 was about 141,500 acres, based on interpretation of data reported in license applications. Water withdrawals to fish holding tanks amounted to 0.73 million gallons per day in 1984. Water-use calculations address the possibility of errors in reporting. About 15 percent of the licensees use municipally supplied water for their holding tanks. One thermoelectric powerplant recently began reusing the heated water from its cooling towers to raise catfish. Little change in the number of licensees since 1980 -indicates that aquaculture is a viable segment of the Minnesota economy. Trout farming has grown from 10 farms in 1978, to 23 in 1984; most use dug ponds sustained by ground-water inflow. Withdrawals for aquaculture are nonconsumptive and are small compared to other water-use categories in Minnesota.

Minnesota↗
USGS1993

Bathymetry of Lake Michie, Durham County, North Carolina, 1990-92

This map report presents the results of a bathymetric survey conducted as part of a 1990-92 study on the effects of sedimentation on Lake Michie, located in northeastern Durham County, North Carolina. Bathymetric data collected at the lake during 1990-92 indicate that, under normal pool conditions at the spillway elevation of 341.0 feet above sea level, the storage volume is 11,070 acre-feet, and the surface area is 508.7 acres. The maximum depth recorded in the lake was 75 feet at approximately 500 feet upstream of Lake Michie Dam.

North Carolina↗