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At least 1,225 records · Page 68Linked to original sources
USGS1995

Geohydrology and water quality of the Durham Center Area, Durham, Connecticut

Contaminated ground water is widespread and persistent beneath the Durham Center area in the town of Durham, Conn. Most of the contaminants are organic halides, usually trichloroethene, 1,1,1-trichloroethane, and tetrachloroethene. Less extensive chemical contamination of surface water, soil, and glacial sediments also has been detected. Two manufacturing companies, located at the northern and southern ends of this largely residential area, are believed to be the principal sources of the organic compounds detected in ground water. The contamination of water in the bedrock, the primary source of drinking water throughout the area, is the major environmental concern. Maximum concentrations of trichloroethene in three bed- rock wells range from 4,500 to about 5,500 mg/L (micrograms per liter). Concentrations of trichloroethene greater than 5 mg/L, the maximum contaminant level established for drinking water by the U.S Environmental Protection Agency, have regularly been detected in water samples from many other bedrock wells for at least 9 years. The geohydrology of the area is highly complex. Compact lodgment till that is up to 30 feet thick and probably fractured, overlies the bedrock. The bedrock is lithologically heterogeneous, and con- sists mostly of red fluvial sandstone, siltstone, and conglomerate; it is locally interbedded with black lacustrine shales and gray sandstones. Lithology and stratigraphy interpreted from borehole-geophysical logs at Durham Center are consistent with the Portland Formation subfacies described in earlier geologic studies. Beds strike nearly north-south and dip gently eastward. At least one high-angle normal fault transects the bedrock; it strikes northeast and dips northwest. Acoustic televiewer logs, measurements at out-crops, and azimuthal, square-array, resistivity data indicate a dominance of northeast-striking fractures that dip steeply northwest and southeast. Less prevalent strike directions are north to east-north-east. The till and sedimentary bedrock are dual-porosity, dual-permeability media. The hydraulic conductivity of the bulk mass of till is believed to be on the order of tenths of a foot per day to about 2.5 feet per day, with a total porosity of about 25 percent and an estimated average fracture porosity of less than 1 percent. The reported transmissivities of the bedrock range from less than 1 to about 17,000 feet squared per day and storativity is generally about 10-4, but the accuracy of these values is uncertain. The intergranular porosity of the sandstone units is estimated to average 5 percent, and estimates of fracture porosity from square-array, resistivity soundings at two sites were 1.1 and 2.7 percent. The bedrock has characteristics of both a single aquifer and a multi-unit, artesian or leaky aquifer system. A local ground-water-flow system that includes the upper part of the bedrock is unconfined. A large- scale flow system in deeper parts of the bedrock has transported organic compounds across topographic drainage divides. Borehole-geophysical logs and head measurements indicate that the natural ground- water-flow system in the bedrock has been altered by drilled wells that connect fractures and by with- drawals from wells. A conceptual model of the movement and fate of organic contaminants suggests that (1) nonaqueous phase organic halides are retained near their source; (2) flow is primarily through fractures in the till and through fractures and bedding-plane openings in the sedimentary rocks; (3) retardation of contaminants occurs primarily by diffusion from fractures into the aquifer matrix; and (4) transport directions of dissolved organic halides are controlled by a combination of natural hydraulic gradients, hydraulic gradients produced by the cyclical pumping of wells, and by the strike directions of bedrock faults, fractures, and bedding planes.

Connecticut↗
USGS1994

Hydrogeologic characterization of a proposed landfill expansion in Pickens County near Easley, South Carolina

This report presents the results of a hydrogeologic study in the Piedmont physiographic province of South Carolina to obtain geologic, hydrologic, and water-quality data from the site of a proposed landfill expansion in Pickens County near Easley, South Carolina. The geology of the study area is typical of the Piedmont region. The unconsolidated regolith on the site is soil and saprolite, which is a product of the weathered parent rock. The soil ranges in thickness from about 5 to 20 feet. The saprolite ranges in thickness from about 5 to 134 feet. The most abundant parent rock type in the area is a biotite gneiss. Ground- and surface-water data were collected at the site. Slug tests on the saprolite indicate a mean hydraulic conductivity of 3 x 0.000003 feet per second. Transmissivity ranges from 12 to 27 cubic feet per day per feet (squared per day). The ground-water velocity for the site ranges from 3 to 6 feet per year. The closest major stream to the site is Golden Creek. Based on low-flow data for Golden Creek, the estimated minimum 7 consecutive day flow that has a recurrence interval of 10 years (7Q10) at station 02186102 is 2.4 cubic feet per second. Water samples were collected from five monitoring wells at the proposed landfill expansion site and from one stream adjacent to the expansion site. Measured pH units ranged from 5.5 to 8.1, and alkalinity concentrations ranged from 5.1 to 73 milligrams per liter as CaCO3. Other water- quality data obtained included temperature and specific conductance, and 5-day BOD (biochemical oxygen demand), bicarbonate, ammonia-nitrogen, nitrite-nitrogen, nitrite plus nitrate, organic carbon, calcium, magnesium, sodium, potassium, chloride, sulfate, fluoride, and selected trace metal concentrations.

South Carolina↗
USGS1994

Lateral movement and stability of channel banks near four highway crossings in southwestern Mississippi

Channel meandering in alluvial streams has caused localized channel instability that has resulted in bridge failure and loss of human life in Mississippi. The U.S. Geological Survey, in coopera- tion with the Mississippi Department of Transpor- tation, conducted a study to develop a better methodology for defining and estimating channel meandering. For this report, river reaches near four bridge sites with current lateral movement of channel banks were selected for study. The lateral movement of channel banks was studied by mapping meanders from aerial photographs taken at various times, evaluating available discharge measurements, and measuring existing channel geometry and soil strength properties at these sites. Rapid, unre- stricted meander cuts and sandy banks are charac- teristic of the sites. Lateral movement was signi- ficant upstream from all four sites, and only one bridge site did not have significant lateral channel-bank movement during the study period. The development of cutbanks and localized channel-bank erosion have caused unstable conditions at three of the sites. Maps of tops of channel indicate significant lateral movement of channel banks upstream and downstream of all four sites and near the bridges at three of four sites. No significant movement occurred at the U.S. Highway 98 crossing of the Bogue Chitto near Tylertown from 1941 to 1991 despite large floods in 1983 and 1990. Slope stability analyses indicated this site to be marginally stable. The maximum lateral movement indicated from maps of tops of channel banks was 680 feet of northward movement of the right (north) bank of the Homochitto River near the State Highway 33 crossing at Rosetta from 1941 to 1983.

Mississippi↗
USGS2000

Water-quality characteristics for selected streams in Lawrence County, South Dakota, 1988-92

During the 1980’s, significant economic development and population growth began to occur in Lawrence County in the northern part of the Black Hills of western South Dakota. Rising gold prices and heap-leach extraction methods allowed the economic recovery of marginal gold ore deposits, resulting in development of several large-scale, open-pit gold mines in Lawrence County. There was increasing local concern regarding potential impacts on the hydrologic system, especially relating to the quantity and quality of water in the numerous streams and springs of Lawrence County. In order to characterize the water quality of selected streams within Lawrence County, samples were collected from 1988 through 1992 at different times of the year and under variable hydrologic conditions. During the time of this study, the Black Hills area was experiencing a drought; thus, most samples were collected during low-flow conditions. Streamflow and water-quality characteristics in Lawrence County are affected by both geologic conditions and precipitation patterns. Most streams that cross outcrops of the Madison Limestone and Minnelusa Formation lose all or large part of their streamflow to aquifer recharge. Streams that are predominantly spring fed have relatively stable streamflow, varying slightly with dry and wet precipitation cycles. Most streams in Lawrence County generally have calcium magnesium bicarbonate type waters. The sites from the mineralized area of central Lawrence County vary slightly from other streams in Lawrence County by having higher concentrations of sodium, less bicarbonate, and more sulfate. False Bottom Creek near Central City has more sulfate than bicarbonate. Nitrogen, phosphorous, and cyanide concentrations were at or near the laboratory reporting limits for most sites and did not exceed any of the water-quality standards. Nitrite plus nitrate concentrations at Annie Creek near Lead, Whitetail Creek at Lead, Squaw Creek near Spearfish, and Spearfish Creek below Robison Gulch were somewhat higher than at other sites. Mining activity, agricultural activity, and domestic development are possible sources of nitrogen to the streams. Increased mining activities were identified as the probable cause of increased nitrogen concentrations in Annie Creek. In the mineralized area of the northern Black Hills, detectable concentrations of trace elements are common in stream water, occasionally exceeding beneficial-use and aquatic-life criteria. In addition, many basins have been disturbed by both historical and recent mining operations and cleanup activities. The maximum dissolved arsenic concentration at Annie Creek near Lead (48 micrograms per liter) approached the current arsenic drinking-water standard. Concentrations at or greater than 5 micrograms per liter were found in samples from Annie Creek near Lead, Spearfish Creek above Spearfish, Whitetail Creek at Lead, and False Bottom Creek near Spearfish. Bear Butte Creek near Deadwood had one sample with a dissolved copper concentration that exceeded acute and chronic aquatic-life criteria. Bear Butte Creek near Deadwood had several manganese concentrations that exceeded the secondary maximum contaminant level of 50 micrograms per liter. Bed-sediment and water-quality data from selected sites in small drainage basins were used to determine if factors such as pH, arsenic concentrations in bed sediments, and calcite saturation control dissolved arsenic concentrations. Arsenic solubility is controlled by adsorption, mainly on ferrihydrite. In addition, adsorption/desorption of arsenic is controlled by the pH of the stream, with high arsenic concentrations appearing only at higher pH conditions (above 8). There are significant arsenic sources available to almost all the small streams of the northern Black Hills mining area, but arsenic is less mobile in streams that are not influenced to the higher pH values by calcite. Streams where arsenic is more mobile have lower iron concentrations in their bed sediments, and they have relatively high concentrations of calcite Additional water-quality data have been collected as part of other studies or monitoring programs by the South Dakota Department of Environment and Natural Resources, U.S. Environmental Protection Agency, U.S. Forest Service, and the U.S. Geological Survey. Summaries of selected data from these other sources are included as additional information.

South Dakota↗
USGS2003

Water quality and trend analysis of Colorado-Big Thompson system reservoirs and related conveyances, 1969 through 2000

The U.S. Geological Survey, in an ongoing cooperative monitoring program with the Northern Colorado Water Conservancy District, Bureau of Reclamation, and City of Fort Collins, has collected water-quality data in north-central Colorado since 1969 in reservoirs and conveyances, such as canals and tunnels, related to the Colorado–Big Thompson Project, a water-storage, collection, and distribution system. Ongoing changes in water use among agricultural and municipal users on the eastern slope of the Rocky Mountains in Colorado, changing land use in reservoir watersheds, and other water-quality issues among Northern Colorado Water Conservancy District customers necessitated a reexamination of water-quality trends in the Colorado–Big Thompson system reservoirs and related conveyances. The sampling sites are on reservoirs, canals, and tunnels in the headwaters of the Colorado River (on the western side of the transcontinental diversion operations) and the headwaters of the Big Thompson River (on the eastern side of the transcontinental diversion operations). Carter Lake Reservoir and Horsetooth Reservoir are off-channel water-storage facilities, located in the foothills of the northern Colorado Front Range, for water supplied from the Colorado–Big Thompson Project. The length of water-quality record ranges from approximately 3 to 30 years depending on the site and the type of measurement or constituent. Changes in sampling frequency, analytical methods, and minimum reporting limits have occurred repeatedly over the period of record. The objective of this report was to complete a retrospective water-quality and trend analysis of reservoir profiles, nutrients, major ions, selected trace elements, chlorophyll- a , and hypolimnetic oxygen data from 1969 through 2000 in Lake Granby, Shadow Mountain Lake, and the Granby Pump Canal in Grand County, Colorado, and Horsetooth Reservoir, Carter Lake, Lake Estes, Alva B. Adams Tunnel, and Olympus Tunnel in Larimer County, Colorado. This report summarizes and assesses: Water-quality and field-measurement profile data collected by the U.S. Geological Survey and stored in the U.S. Geological Survey National Water Information System, Time-series trends of chemical constituents and physical properties, Trends in oxygen deficits in the hypolimnion of the reservoirs in the late summer season by the seasonal Kendall trend test method, Nutrient limitation and trophic status indicators, and Water-quality data in terms of Colorado water-quality standards. Water quality was generally acceptable for primary uses throughout the Colorado–Big Thompson system over the site periods of record, which are all within the span of 1969 to 2000. Dissolved solids and nutrient concentrations were low and typical of a forested/mountainous/crystalline bedrock hydrologic setting. Most of the more toxic trace elements were rarely detected or were found in low concentrations, due at least in part to a relative lack of ore-mineral deposits within the drainage areas of the Colorado–Big Thompson Project. Constituent concentrations consistently met water-quality standard thresholds set by the State of Colorado. Trophic-State Index Values indicated mesotrophic conditions generally prevailed at reservoirs, based on available Secchi depth, total phosphorus concentrations, and chlorophyll- a concentrations. Based on plots of time-series values and concentrations and seasonal Kendall nonparametric trends testing, dissolved solids and most major ions are decreasing at most sites. Many of the nutrient data did not meet the minimum criteria for time-series testing; but for those that did, nutrient concentrations were generally stable (no statistical trend) or decreasing (ammonia plus organic nitrogen and total phosphorus). Iron and manganese concentrations were stable or decreasing at most sites that met testing criteria. Chlorophyll- a data were only collected for 11 years but generally indicated quasi-stable or downward temporal trends.

Colorado↗
USGS1996

Physical and chemical characteristics of Lake Powell at the forebay and outflows of Glen Canyon Dam, northeastern Arizona, 1990-91

The physical and chemical characteristics of Lake Powell have a direct effect on the quality of water below Glen Canyon Dam. Understanding the physical and chemical characteristics of the lake and outflows from the dam is essential in order to effectively manage the operation of the dam. During August 1990 to September 1991, physical and chemical measurements were made and water samples were collected in the forebay of Lake Powell and at the outflows (draft tubes) of Glen Canyon Dam to document the physical and chemical characteristics of water entering the Colorado River. A persistent chemocline in the forebay of Lake Powell fluctuated seasonally during the study. Thermal stratification began in mid-April and persisted into late October. Spatial variation of specific conductance, pH, water temperature, and dissolved-oxygen concentration in the forebay was negligible. Sodium and sulfate were the dominant ions. Major ions, nutrients, and metals generally increased in concentration with depth in the forebay. Concentrations of dissolved nitrogen (as nitrite plus nitrate) in the forebay ranged from less than 0.02 to 0.58 milligrams per liter. Strontium and lithium were the most abundant metals. Dissolved organic carbon ranged from about 2.6 to 4.9 milligrams per. liter with larger concentrations generally occurring in the epilimnion. No diel variations of chemical constituents were observed. Vertical-attenuation coefficients of light penetration in the forebay ranged from 0.058 to 0.080 microeinsteins per meter squared per second, and the euphotic depth ranged from about 82 to 113 feet. Generally, the physical and chemical characteristics of outflows through the draft tubes of Glen Canyon Dam were similar to the physical and chemical characteristics of the water at penstock depth and deeper depths. Specific conductance ranged from 803 to 1,090 microsiemens per centimeter, and pH values ranged from about 7.2 to 8.0. Water temperatures measured in the outflows ranged from 7.0 to 9.0 degrees Celsius, and dissolved oxygen ranged from about 6.5 to 9.1 milligrams per liter. Concentrations of dissolved nitrogen (as nitrite plus nitrate) ranged from 0.13 to 0.74 milligrams per liter. Dissolved phosphorus (as orthophosphate) and ammonia (NH4) generally were less than the minimum reporting level of 0.01 milligrams per liter. Availability and Quality of Water from Drift Aquifers in Marshall, Pennington, Polk, and Red Lake Counties, Northwestern Minnesota By R.J. Lindgren Abstract Sand and gravel aquifers present within glacial deposits are important sources of water in Marshall, Pennington, Polk, and Red Lake Counties in northwestern Minnesota. Saturated thicknesses of the unconfined aquifers range from 0 to 30 feet. Estimated horizontal hydraulic conductivities range from 2.5 to 600 feet per day. Transmissivity of the unconfined aquifers ranges from 33 to greater than 3,910 feet squared per day. Theoretical maximum well yields for 6 wells with specific-capacity data range from 12 to 123 gallons per minute. Saturated thicknesses of shallow confined aquifers (depth to top of the aquifer less than 100 feet below land surface) range from 0 to 150 feet. Thicknesses of intermediate, deep, and basal confined aquifers (depths to top of the aquifer from 100 to 199 feet, from 200 to 299 feet, and 300 feet or more below land surface, respectively) range from 0 to more than 126 feet. Transmissivity of the confined aquifers ranges from 2 to greater than 210,000 feet squared per day. Theoretical maximum well yields range from 3 to about 2,000 gallons per minute. Recharge to ground water is predominantly from precipitation that percolates downward to the saturated zone. Recharge to unconfined aquifers in the study area ranged from 4.5 to 12.0 inches per year during 1991 and 1992, based on hydrograph analysis. Model simulations done for this study indicate that recharge rates from 8 to 9 inches per year to unconfined aquifers produce the best matches

Water-Resources Investigations Report↗
USGS2002

Water quality, sediment quality, and stream-channel classification of Rock Creek, Washington, D.C., 1999-2000

Rock Creek Park is within the National Capital Region in Washington, D.C., and is maintained by the National Park Service. Part of Montgomery County, Maryland, and part of the District of Columbia drain into Rock Creek, which is a tributary of the Potomac River. Water quality in Rock Creek is important to biotic life in and near the creek, and in the Potomac River Basin and the Chesapeake Bay. The water quality of the Rock Creek Basin has been affected by continued urban and agricultural growth and development. The U.S. Geological Survey, in cooperation with the National Park Service, investigated water quality and sediment quality in Rock Creek over a 2-year period (1998?2000), and performed a stream-channel classification to determine the distribution of bottom sediment in Rock Creek. This report presents and evaluates water quality and bottom sediment in Rock Creek for water years 1999 (October 1, 1998 to September 30, 1999) and 2000 (October 1, 1999 to September 30, 2000). A synoptic surface-water assessment was conducted at five stations from June 23 to June 25, 1999, a temporal surface-water assessment was conducted at one station from February 18, 1999 to September 26, 2000, and bed-sediment samples were collected and assessed from three stations from August 17 to August 19, 1999. The synoptic surface-water assessment included pesticides (parent compounds and selected transformation products), field parameters, nutrients, and major ions. The temporal surface-water assessment included pesticides (parent compounds and selected transformation products) and field parameters. The bed-sediment assessment included trace elements and organic compounds (including low- and high-molecular weight polycyclic aromatic hydrocarbons, poly-chlorinated biphenyls, pesticides, and phthalates). Some, but not all, of the pesticides known to be used in the area were included in the synoptic water-quality assessment, the temporal water-quality assessment, and the bed-sediment assessment. In addition to the water-quality and sediment-quality assessments, a Rosgen stream-channel classification was performed on a 900-foot-long segment of Rock Creek. In the synoptic water-quality assessment, two pesticides were found to be above published criteria for the protection of aquatic life. In the temporal water-quality assessment, four pesticides were found to be above published criteria for the protection of aquatic life. In the bed-sediment assessment, 8 trace elements, 14 polycyclic aromatic hydrocarbons, 6 pesticides, and 1 phthalate compound were found to be above published criteria for the protection of aquatic life. In the Rosgen classification, a comparison to a previous classification for this segment showed an increase in sands and other fine-grained sediments in the creek bed.

Water-Resources Investigations Report↗
USGS2000

Methodology for applying monitored natural attenuation to petroleum hydrocarbon-contaminated ground-water systems with examples from South Carolina

Natural attenuation processes such as dispersion, advection, and biogradation serve to decrease concentrations of disssolved contaminants as they are transported in all ground-water systems. However, the efficiency of these natural attenuation processes and the degree to which they help attain remediation goals, varies considerably from site to site. This report provides a methodology for quantifying various natural attenuation mechanisms. This methodology incorporates information on (1) concentrations of contaminants in space and/or time; (2) ambient reduction/oxidation (redox) conditions; (3) rates and directions of ground-water flow; (4) rates of contaminant biodegradation; and (5) demographic considerations, such as the presence of nearby receptor exposure points or property boundaries. This document outlines the hydrologic, geochemical, and biologic data needed to assess the efficiency of natural attenuation, provides a screening tool for making preliminary assessments, and provides examples of how to determine when natural attenuation can be a useful component of site remediation at leaking underground storage tank sites. At a site in the Piedmont Physiographic Province (Laurens, South Carolina), hydrologic and water-chemistry data indicate that the natural attenuation capacity for benzene is approximately 5 percent per foot of flowpath. As a result, benzene concentrations would decrease from about 28,000 micrograms per liter in ground water at the source area to less than 5 micrograms per liter 200 feet downgradient and prior to discharging to a stream. Because of this rapid attenuation, contaminants do not presently impact the stream downgradient of the site. In contrast, at a site in the coastal Plain Physiographic Province (Charleston, South Carolina), hydrologic and water-chemistry data indicate that, even thought the site has a substantial natural attenuation capacity, it may not be sufficient to fully protect a nearby point of ground-water discharge. These two sites illustrate how the efficiency of natural attenuation processes acting on petroleum hydrocarbons can be systematically evaluated using hydrologic, geochemical, and microbiologic methods. These methods, in turn, can be used to assess the role that the natural attenuation of petroleum hydrocarbons can play in achieving overall site remediation.

South Carolina↗
USGS1987

Geohydrology and susceptibility of major aquifers to surface contamination in Alabama; area 1

This report delineates and describes the geohydrology and susceptibility of the major aquifers to contamination in Area 1 - Colbert, Franklin, Lauderdale, Lawrence, Limeston, Madison, and Morgan Counties. Most of the area is underlain by a Mississippian carbonate sequence that includes two major aquifers, the Tuscumbia-Fort Payne aquifer and the Bangor aquifer. A third major aquifer, the Tuscaloosa aquifer of Cretaceous age, occurs in the southwest part of the area. The Mississippi carbonate aquifers are the Tuscumbia-Fort Payne aquifer which includes most Tuscumbia Limestone and the Fort Payne Chert, and a small area of the Monteagle Limestone, and the Bangor aquifer which includes the Bangor Limestone and Hartselle Sandstone. Both of these aquifers possess highly-variable secondary porosity and permeability related to fractures that have been enlarged, sometimes to cavernous proportions, due to solution processes. The Tuscaloosa aquifer consists of the Tuscaloosa Group, an unconsolidated clastic deposit that has relatively uniform primary porosity and permeability. Significant quantities of groundwater are available from each of the aquifers. Water levels at nearly 2 ,000 wells indicate that, for each aquifer, general groundwater movement is from topographically high to low areas. Each of the aquifers is recharged throughout its outcrop in the study area and is susceptible to contamination within the outcrop. Generalized topographic settings such as closed-contour depressions are identified as areas that are highly susceptible to contamination. Specific features such as sinkholes also are identified as extremely susceptible to contamination.

Alabama↗
USGS1997

Water-quality assessment of the Rio Grande Valley, Colorado, New Mexico and Texas: Organic compounds and trace elements in bed sediment and fish tissue, 1992-93

The occurrence and distribution of contaminants in aquatic systems are major components of the National Water-Quality Assessment (NAWQA) Program. Bed-sediment samples were collected at 18 sites in the Rio Grande Valley study unit between September 1992 and March 1993 to characterize the geographic distribution of organic compounds, including chlorinated insecticides, polychlorinated biphenyls (PCB's), and other chlorinated hydrocarbons, and also trace elements. Two-millimeter-size- fraction sediment was analyzed for organic compounds and less than 63-micron-size-fraction sediment was analyzed for trace elements. Concentrations of p,p'-DDE were detected in 33 percent of the bed-sediment samples. With the exception of DDT-related compounds, no other organochlorine insecticides or polychlorinated biphenyls were detected in samples of bed sediment. Whole-body fish samples were collected at 11 of the bed- sediment sites and analyzed for organic compounds. Organic compounds were reported more frequently in samples of fish, and more types of organic compounds were found in whole-body fish samples than in bed-sediment samples. Concentrations of p,p'-DDE were detected in 91 percent of whole-body fish samples. Polychlorinated biphenyls, cis-chlordane, trans-chlordane, trans- nonachlor, and hexachlorobenzene were other organic compounds detected in whole-body samples of fish from at least one site. Because of the extent of mineralized areas in the Rio Grande Basin arsenic, cadmium, copper, lead, mercury, selenium, and zinc concentrations in bed-sediment samples could represent natural conditions at most sites. However, a combination of natural conditions and human activities appears to be associated with elevated trace-element concentrations in the bed-sediment sample from the site Rio Grande near Creede, Colorado, because this sample exceeded the background trace-element concentrations calculated for this study. Fish-liver samples were collected at 12 of the bed-sediment sites and analyzed for trace elements. Certain trace elements were detected at higher concentrations in fish-liver samples than in bed-sediment samples from the same site. Both bed-sediment and fish-tissue samples are necessary for a complete environmental assessment of the occurrence and distribution of trace elements.

Colorado, New Mexico, Texas↗
USGS1994

A technique for estimating ground-water levels at sites in Rhode Island from observation-well data

Estimates of future high, median, and low ground-water levels in Rhode Island are needed for engineering and architectural design decisions and for appropriate selection of land uses. For example, the failure of individual underground sewage-disposal systems due to high ground-water levels can be avoided if accurate water-level estimates are available. Estimates of extreme or average conditions are needed because short-duration re-construction observations are unlikely to be representative. The technique described in this report utilizes a single water-level measurement at a site of interest, in combination with a long-term water-level record at an observation well, to estimate the long-term high, median, and low water levels at the site of interest. The transfer of information to the site of interest depends on four fundamental assumptions: (1) Water levels will fluctuate in the future as they have in the past, (2) Water levels fluctuate seasonally, (3) Ground-water fluctuations depend on site geology, and (4) Water levels throughout Rhode Island are affected by similar precipitation and climate. The technique is based on the equivalent relation between the ratio of potential water-level change to maximum annual water-level range at the site and the ratio of potential water-level change to annual water-level range at the observation well. Equations for estimating high, median, and low water levels, and graphs of probable annual water-level range are given for selecting representative ranges of water levels for sand and gravel and till in Rhode Island. The accuracy of the technique is evaluated by use of the equations to estimate water levels at long-term observation wells where high, median, and low water levels are known from monthly measurements over many years. As a test of the estimating procedure, 6,697 estimates each of high, median, and low water levels (depth to water level exceeded 95, 50, and 5 percent of the time, respectively) were compared with measured water levels exceeded 95, 50, and 5 percent of the time at 14 sites unaffected by pumping or other known factors. Mean squared errors (average differences squared, between estimated and measured water levels) for the estimates ranged from 0.34 to 1.53 ft 2 for high water levels, 0.30 to 1.22 ft 2 for median water levels, and 0.32 to 2.55 ft 2 for low water levels. All mean squared errors are less than the State required 3-foot separation between the bottom of the stone underlying the seepage system and the maximum altitude of the water table. This degree of accuracy is acceptable for many design purposes.

Rhode Island↗
USGS1976

Magnitude and frequency of floods in Nebraska

Estimates of flood characteristics with recurrence intervals up to 100 years can be obtained at most sites in Nebraska by use of techniques presented in this report. Instructions, equations, and graphs are presented to aid the design engineer in estimating the magnitude and frequency of floods. For natural-flow streams, the estimating equations and graphical solutions are based on regional relations between floods of a specific return period and selected basin characteristics. Nebraska was subdivided into five hydrologic regions by means of regressions and residuals from the regressions. The boundaries of Regions 1 and 2 were determined to a great extent by differences in soil type. The divisions between Region 2 and Region 4 were also determined by differences in soil type. Boundaries of Region 3 and Region 5 are along or near basin divides. Flood magnitude and frequency solution diagrams are presented for major controlled streams such as the North Platte, South Platte, Platte, and Republican Rivers. Flood information on small controlled streams is limited to available station data. Flood characteristics are tabulated for 303 gaging stations having 13 or more years of record. These flood characteristics provide the best information on floods at these gaged sites. Observed maximum flood peaks at 303 gaging stations with 13 or more years of record and significant peaks at 57 short-term stations and 31 miscellaneous sites are useful in designing flood-control works for maximum safety from flood damage. Comparison is made with maximum observed floods in the United States.

Nebraska↗
USGS2002

Report of hydrologic investigations in the Three Sisters area of central Oregon, Summer 2001

An ongoing episode of crustal uplift centered in the Separation Creek drainage of the Three Sisters area, central Oregon Cascades, may result from a magmatic intrusion that began in 1998. An investigation of springs in this drainage in summer 2001 revealed slightly elevated water temperatures and chloride (Cl-) concentrations of up to about 5?C and 20 milligrams per liter (mg/L), respectively, above background. The total discharge of anomalous Cl- in Separation Creek was 9.2 grams per second, which in combination with the temperature-Cl- relation in the springs results in a total advective heat discharge of 16 MW (megawatts). Comparison with similar findings obtained a decade earlier suggests that total Cl- and heat discharges in the groundwater drainage are unaffected by the current uplift. However, the isotopic composition of the dissolved inorganic carbon (DIC) in the spring waters (delta carbon-13 (13C) = -9.03 to -11.6?; carbon-14 (14C) <25 pmC) combined with helium-3/helium-4 (3He/4He) ratios near 8 RA and C/3He ratios <1010 in two of the springs are indicative of a magmatic source. The high 3He/4He ratios indicate that the magmatic gas is derived from a relatively recent, if not ongoing, intrusion. The concentration of magmatic carbon is low, a few millimoles per liter (mmol/L) at most, with an average value of 1.53 mmol/L for all the springs sampled in the drainage. Combining this average with the late-summer water flow in Separation Creek suggests a discharge of 21 tonnes/day of magmatic carbon dioxide (CO2). The presence of magmatic carbon in the shallow groundwater system, and the fact that DIC is uncorrelated with Cl-, suggests that some magmatic gas could escape diffusely through the soils.

Water-Resources Investigations Report↗
USGS1983

Geologic and well-construction data for the H-10 borehole complex near the proposed Waste Isolation Pilot Plant site, southeastern New Mexico

The H-10 borehole complex, a group of three closely spaced boreholes, is located 3 1/2 miles southeast of the proposed Waste Isolation Pilot Plant site in west-central Lea County, New Mexico. The geological data presented in this report are part of a site-characterization study for the possible storage of defense-associated radioactive wastes within salt beds of the Salado Formation of Permian age. Each borehole was designated to penetrate a distinct water-bearing zone: H-10a (total depth 1 ,318 feet) was completed just below the Magenta Dolomite Member of the Rustler Formation of Permian age; H-10b (total depth 1 ,398 feet) was completed just below the Culebra Dolomite Member of the Rustler Formation; and H-10c (total depth 1,538 feet) was completed below the Rustler Formation-Salado Formation contact. The geologic units penetrated in borehole H-10c are surficial alluvium and eolian sand of Holocene age (0-5 feet); the Mescalero caliche (5-9 feet) and the Gatuna Formation (9-90 feet) of Pleistocene age; formation in the Dockum Group (Chinle Formation, 90-482 feet and Santa Rosa Sandstone, 482-658 feet) of Late Triassic age; and the Dewey Lake Red Beds (658-1,204 feet), the Rustler Formation (1,204-1,501 feet), and part of the Salado Formation (1,501-1,538 feet), all of Permian age. The sections of the Rustler and Salado Formations penetrated by borehole H-10c are complete and contain little or no evidence of dissolution of halite and associated rocks, indicating that the eastward-moving dissolution on top of the Salado, found just to the west of the WIPP site, has not reached the H-10 site. (USGS)

Water-Resources Investigations Report↗
USGS2003

Using water-quality profiles to characterize seasonal water quality and loading in the upper Animas River basin, southwestern Colorado

One of the important types of information needed to characterize water quality in streams affected by historical mining is the seasonal pattern of toxic trace-metal concentrations and loads. Seasonal patterns in water quality are estimated in this report using a technique called water-quality profiling. Water-quality profiling allows land managers and scientists to assess priority areas to be targeted for characterization and(or) remediation by quantifying the timing and magnitude of contaminant occurrence. Streamflow and water-quality data collected at 15 sites in the upper Animas River Basin during water years 1991?99 were used to develop water-quality profiles. Data collected at each sampling site were used to develop ordinary least-squares regression models for streamflow and constituent concentrations. Streamflow was estimated by correlating instantaneous streamflow measured at ungaged sites with continuous streamflow records from streamflow-gaging stations in the subbasin. Water-quality regression models were developed to estimate hardness and dissolved cadmium, copper, and zinc concentrations based on streamflow and seasonal terms. Results from the regression models were used to calculate water-quality profiles for streamflow, constituent concentrations, and loads. Quantification of cadmium, copper, and zinc loads in a stream segment in Mineral Creek (sites M27 to M34) was presented as an example application of water-quality profiling. The application used a method of mass accounting to quantify the portion of metal loading in the segment derived from uncharacterized sources during different seasonal periods. During May, uncharacterized sources contributed nearly 95 percent of the cadmium load, 0 percent of the copper load (or uncharacterized sources also are attenuated), and about 85 percent of the zinc load at M34. During September, uncharacterized sources contributed about 86 percent of the cadmium load, 0 percent of the copper load (or uncharacterized sources also are attenuated), and about 52 percent of the zinc load at M34. Characterized sources accounted for more of the loading gains estimated in the example reach during September, possibly indicating the presence of diffuse inputs during snowmelt runoff. The results indicate that metal sources in the upper Animas River Basin may change substantially with season, regardless of the source.

Colorado↗
USGS1979

Comparison of selected cultural, physical, and water-quality characteristics of lakes in Washington

This report presents comparisons and a graphical overview of the relative magnitude and the regional and statewide distribution of 19 selected cultural, physical, and water-quality characteristics measured in a reconnaissance study of several hundred lakes in Washington. The selected characteristics presented for each lake include types of land use in the lake drainage basin, shoreline residential development, altitude of lake, mean lake depth, nitrogen and phosphorus concentrations in upper and bottom waters, specific conductance, temperature and dissolved-oxygen concentration cf bottom water, Secchi-disc visibility, emersed macrophytes covering shoreline and lake surface, and fecal-coliform bacteria. Statewide, about two-thirds of the lake drainage basins studied have more than half their land in forest. Urban and suburban developments of the basins are highest in the more populated western Washington counties near Puget Sound, whereas most land in the drainage basins of lakes in the Columbia Plateau of eastern Washington is used for agricultural purposes. Statewide, almost one-fourth of the lakes are shallow (mean depth 2.0 meters or less) and only 7 percent of the lakes have mean depths greater than 20 meters. Dissolved-oxygen layering in summer was detected in many lakes throughout the State. The oxygen concentrations in the upper waters of these lakes were typically near saturation, but the bottom waters of many were severely depleted. Statewide, about one-third of the lakes had Secchi-disc readings of 2.0 meters or less, a value often considered characteristic of eutrophic lakes. The poorest water clarity was observed in the Columbia Plateau, where 68 percent of the lakes had Secchi-disc readings of less than 2.0 meters. Statewide, the median concentration of total phosphorus in the upper waters of lakes was 20 micrograms per liter. More than one-third of the lakes in the State had total phosphorus concentrations in their upper waters that exceeded 30 micrograms per liter, a concentration that is often considered characteristic of eutrophic lakes.

Washington↗
USGS1988

Stratigraphic and hydrogeologic framework of the Alabama Coastal Plain

Tertiary and Cretaceous sand aquifers of the Southeastern United States Coastal Plain comprise a major multlstate aquifer system informally defined as the Southeastern Coastal Plain aquifer system, which is being studied as part of the U.S. Geological Survey's Regional Aquifer System Analysis (RASA) program. The major objectives of each RASA study are to identify, delineate, and map the distribution of permeable clastlc rock, to examine the pattern of ground-water flow within the regional aquifers, and to develop digital computer simulations to understand the flow system. The Coastal Plain aquifers in Alabama are being studied as a part of this system. This report describes the stratlgraphlc framework of the Cretaceous, Tertiary, and Quaternary Systems in Alabama to aid in delineating aquifers and confining units within the thick sequence of sediments that comprises the Southeastern Coastal Plain aquifer system in the State. Stratigraphlc units of Cretaceous and Tertiary age that make up most of the aquifer system in the Coastal Plain of Alabama consist of clastlc deposits of Early Cretaceous age; the Coker and Gordo Formations of the Tuscaloosa Group, Eutaw Formation, and Selma Group of Late Cretaceous age; and the Midway, Wilcox, and Clalborne Groups of Tertiary age. However, stratigraphlc units of late Eocene to Holocene age partially overlie and are hydraulically connected to clastic deposits in southern Alabama. These upper carbonate and clastlc stratlgraphic units also are part of the adjoining Florldan and Gulf Coastal Lowlands aquifer systems. The Coastal Plain aquifer system is underlain by pre-Cretaceous rocks consisting of low-permeabillty sedimentary rocks of Paleozolc, Triassic, and Jurassic age, and a complex of metamorphic and igneous rocks of Precambrian and Paleozolc age similar to those found near the surface in the Piedmont physiographic province. Twelve hydrogeologlc units in the Alabama Coastal Plain are defined--slx aquifers and six confining units. Aquifers of the Coastal Plain aquifer system are composed of fine to coarse sand, gravel, and limestone; confining beds are composed of clay, shale, chalk, marl, and metamorphic and igneous rocks.

Water-Resources Investigations Report↗
USGS1994

Estimating the magnitude and frequency of low flows of streams in Massachusetts

The report presents techniques used for estimating 7-day 2-year (7Q2) and 7-day 10-year (7Q10) flows at continuous-record streamflow-gaging stations, partial-record stations, and ungaged sites on streams in Massachusetts. A two-parameter log-normal probability distribution was used to compute low flows at 31 continuous-record stream-flow-gaging stations. Graphical and mathematical techniques were used to estimate low flows at partial-record stations. Regional regression techniques commonly are used to estimate 7Q2 and 7Q10 flows at ungaged stream sites. The development and application of a low-flow regression model is described. The model contains two parameters, mean and standard deviation, computed from separate regression equations that use total drainage area and basin relief as independent variables. The coefficients of determination of the mean and standard deviation regression equations are 0.964 and 0.960, respec- tively; the percentage of standard error of the regression of each equation are 35 and 34, respec- tively. The model is applicable for basins in Massachusetts having a drainage area of 5 to 150 square miles, a slope of less than 4 percent, and an area of stratified drift greater than 4 percent of the total drainage area. A computer program is presented that can be used to compute 7Q2 and 7Q10 flows and the 95-percent intervals of confidence and prediction for a given basin.

Water-Resources Investigations Report↗