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USGS2002

Quality of shallow ground water in areas of recent residential and commercial development, Wichita, Kansas, 2000

Water samples from 30 randomly distributed monitoring wells in areas of recent residential and commercial development (1960–96), Wichita, Kansas, were collected in 2000 as part of the High Plains Regional Ground-Water Study conducted by the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program. The samples were analyzed for about 170 water-quality constituents that included chlorofluorocarbons, physical properties, dissolved solids and major ions, nutrients and dissolved organic carbon, trace elements, pesticide compounds, and volatile organic compounds. The purpose of this report is to provide an assessment of water quality in recharge to shallow ground water underlying areas of recent residential and commercial development and to determine the relation of ground-water quality to overlying urban land use. Analyses of water from the 30 monitoring wells for chlorofluorocarbons were used to estimate apparent dates of recharge. Water from 18 wells with nondegraded and uncontaminated chlorofluorocarbon concentrations had calculated apparent recharge dates that ranged from 1979 to 1990 with an average date of 1986. Water from 14 monitoring wells (47 percent) exceeded the 500-milligrams-per-liter Secondary Maximum Contaminant Level established by the U.S. Environmental Protection Agency for dissolved solids in drinking water. The Secondary Maximum Contaminant Levels of 250 milligrams per liter for chloride and sulfate were exceeded in water from one well. The source of the largest concentrations of dissolved solids and associated ions, such as chloride and sulfate, in shallow ground water in the study area probably is highly mineralized water moving out of the Arkansas River into the adjacent, unconsolidated deposits and mixing with the dominant calcium bicarbonate water in the deposits. Concentrations of most nutrients in water from the sampled wells were small, with the exception of nitrate. Although water from the sampled wells did not have nitrate concentrations larger than the 10-milligram-per-liter Maximum Contaminant Level for drinking water, water from 50 percent of the sampled wells showed nitrate enrichment (concentrations greater than 2.0 milligrams per liter). Most trace elements in water from the sampled wells were detected only in small concentrations, and few exceeded respective water-quality standards. Twenty percent of iron concentrations, 40 percent of manganese concentrations, 3 percent of arsenic concentrations, and 13 percent of uranium concentrations exceeded respective Maximum Contaminant Levels or Secondary Maximum Contaminant Levels. A total of 47 pesticide compounds were analyzed in ground-water samples during this study. Water from 73 percent of the wells sampled had detectable concentrations of one or more of 8 of these 47 compounds. The herbicide atrazine or its degradation product deethylatrazine were detected most frequently (in water from 70 percent of the sampled wells). Metolachlor was detected in water from 10 percent of the wells, and simazine was detected in water from 30 percent of the wells sampled. Other pesticides detected included dieldrin, pendimethalin, prometon, and tebuthiuron (each in water from 3 percent of the wells). All concentrations of these compounds were less than established Maximum Contaminant Levels. A total of 85 volatile organic compounds (VOCs) were analyzed in ground-water samples during this study. Water from 43 percent of the wells had a detectable concentration of one or more VOCs. Chloroform was the most frequently detected VOC (23 percent of the wells sampled).Seven other VOCs were detected in water at frequencies of 13 percent or less in the wells sampled. Concentrations of VOCs were less than respective Maximum Contaminant Levels, except one sample with a concentration of 9.0 micrograms per liter for tetrachloroethylene (Maximum Contaminant Level of 5.0 micrograms per liter). An analysis of hydraulic gradient, flow velocity, and residence time of the ground water indicated potential recharge areas that ranged from 0.8 to 2.8 miles upgradient of monitoring-well locations. Nineteen (63 percent) of these potential recharge areas were in agricultural areas or areas in transition from agricultural to residential and (or) commercial land use at the time water sampled from the monitoring wells was recharged to the shallow ground water. The occurrence of atrazine or deethylatrazine in water from 70 percent of the monitoring wells may indicate a historical agricultural land-use relation. This agricultural relation also may affect concentrations of other water-quality constituents of possible agricultural origin such as nitrate, which generally were in excess of background concentrations in shallow ground water.

Kansas↗

USGS2003

Forest Types in the Lower Suwannee River Floodplain, Florida?-A Report and Interactive Map

A map of forest types in the lower Suwannee River floodplain, Florida, was created during a study conducted from 1996 to 2000 by the U.S. Geological Survey in cooperation with the Suwannee River Water Management District. The map is presented with this report on a compact disc with interactive viewing software. The forest map can be used by scientists for ecological studies in the floodplain based on land cover types and by landowners and management personnel making land use decisions. The study area is the 10-year floodplain of the lower Suwannee River from its confluence with the Santa Fe River to the lower limit of forests near the Gulf of Mexico. The floodplain is divided into three reaches: riverine (non-tidal), upper tidal, and lower tidal, due to changes in hydrology, vegetation, and soils with proximity to the coast. The 10-year floodplain covers about 21,170 hectares; nearly 88 percent of this area (18,580 hectares) is mapped as 14 major forest types. Approximately 29 percent (5,319 hectares) of these forests have been altered by agriculture or development. About 75 percent of the area of major forest types (13,994 hectares) is wetland forests and about 25 percent (4,586 hectares) is upland forests. Tidal wetland forests (8,955 hectares) cover a much greater area than riverine wetland forests (5,039 hectares). Oak/pine upland forests are present in the riverine and upper tidal reaches of the floodplain on elevations that are inundated only briefly during the highest floods. High bottomland hardwoods are present on the higher levees, ridges, and flats of the riverine reach where soils are usually sandy. Low bottomland hardwood forests are present in the riverine reach on swamp margins and low levees and flats that are flooded continuously for several weeks or longer every 1 to 3 years. Riverine swamps are present in the lowest and wettest areas of the non-tidal floodplain that are either inundated or saturated most of the time. Upper tidal bottomland hardwood forests are present on sandy soils on high flats and in transitional areas between upland forests and swamps. Upper tidal mixed forests are found on low levees or between swamps and higher forest types. Upper tidal swamps are present at elevations below median monthly high stage and usually have surface soils that are permanently saturated mucks. Lower tidal hammocks are found on higher elevations that do not receive regular tidal inundation but have a high water table and are briefly inundated by storm surges several times a decade. Lower tidal mixed forests include swamps with numerous small hummocks or less common larger hummocks. Lower tidal swamps are found on deep muck soils that are below the elevation of the median daily or monthly high stage. Seven additional land cover types (2,590 hectares) are mapped. Water in the main channel of the lower Suwannee River (1,767 hectares) was mapped separately from open water in the floodplain (239 hectares). Other land cover types are: seepage slopes (70 hectares), isolated forested wetlands (19 hectares), marshes upstream of the tree line (505 hectares), beds of emergent aquatic vegetation (21 hectares), and floodplain glades (46 hectares)

Water-Resources Investigations Report↗

USGS1996

Uncertainty analysis of the simulations of effects of discharging treated wastewater to the Red River of the North at Fargo, North Dakota, and Moorhead, Minnesota

Two separate studies to simulate the effects of discharging treated wastewater to the Red River of the North at Fargo, North Dakota, and Moorhead, Minnesota, have been completed. In the first study, the Red River at Fargo Water-Quality Model was calibrated and verified for icefree conditions. In the second study, the Red River at Fargo Ice-Cover Water-Quality Model was verified for ice-cover conditions. To better understand and apply the Red River at Fargo Water-Quality Model and the Red River at Fargo Ice-Cover Water-Quality Model, the uncertainty associated with simulated constituent concentrations and property values was analyzed and quantified using the Enhanced Stream Water Quality Model-Uncertainty Analysis. The Monte Carlo simulation and first-order error analysis methods were used to analyze the uncertainty in simulated values for six constituents and properties at sites 5, 10, and 14 (upstream to downstream order). The constituents and properties analyzed for uncertainty are specific conductance, total organic nitrogen (reported as nitrogen), total ammonia (reported as nitrogen), total nitrite plus nitrate (reported as nitrogen), 5-day carbonaceous biochemical oxygen demand for ice-cover conditions and ultimate carbonaceous biochemical oxygen demand for ice-free conditions, and dissolved oxygen. Results are given in detail for both the ice-cover and ice-free conditions for specific conductance, total ammonia, and dissolved oxygen. The sensitivity and uncertainty of the simulated constituent concentrations and property values to input variables differ substantially between ice-cover and ice-free conditions. During ice-cover conditions, simulated specific-conductance values are most sensitive to the headwatersource specific-conductance values upstream of site 10 and the point-source specific-conductance values downstream of site 10. These headwater-source and point-source specific-conductance values also are the key sources of uncertainty. Simulated total ammonia concentrations are most sensitive to the point-source total ammonia concentrations at all three sites. Other input variables that contribute substantially to the variability of simulated total ammonia concentrations are the headwater-source total ammonia and the instream reaction coefficient for biological decay of total ammonia to total nitrite. Simulated dissolved-oxygen concentrations at all three sites are most sensitive to headwater-source dissolved-oxygen concentration. This input variable is the key source of variability for simulated dissolved-oxygen concentrations at sites 5 and 10. Headwatersource and point-source dissolved-oxygen concentrations are the key sources of variability for simulated dissolved-oxygen concentrations at site 14. During ice-free conditions, simulated specific-conductance values at all three sites are most sensitive to the headwater-source specific-conductance values. Headwater-source specificconductance values also are the key source of uncertainty. The input variables to which total ammonia and dissolved oxygen are most sensitive vary from site to site and may or may not correspond to the input variables that contribute the most to the variability. The input variables that contribute the most to the variability of simulated total ammonia concentrations are pointsource total ammonia, instream reaction coefficient for biological decay of total ammonia to total nitrite, and Manning's roughness coefficient. The input variables that contribute the most to the variability of simulated dissolved-oxygen concentrations are reaeration rate, sediment oxygen demand rate, and headwater-source algae as chlorophyll a.

Water-Resources Investigations Report↗

USGS2001

Summary of and factors affecting pesticide concentrations in streams and shallow wells of the lower Susquehanna River basin, Pennsylvania and Maryland, 1993-95

This report presents the detection frequency of 83 analyzed pesticides, describes the concentrations of those pesticides measured in water from streams and shallow wells, and presents conceptual models of the major factors affecting seasonal and areal patterns of pesticide concentrations in water from streams and shallow wells in the Lower Susquehanna River Basin. Seasonal and areal patterns of pesticide concentrations were observed in 577 samples and nearly 40,000 pesticide analyses collected from 155 stream sites and 169 shallow wells from 1993 to 1995. For this study, shallow wells were defined as those generally less than 200 feet deep. The most commonly detected pesticides were agricultural herbicides?atrazine, metolachlor, simazine, prometon, alachlor, and cyanazine. Atrazine and metolachlor are the two most-used agricultural pesticides in the Lower Susquehanna River Basin. Atrazine was detected in 92 percent of all the samples and in 98 percent of the stream samples. Metolachlor was detected in 83 percent of all the samples and in 95 percent of the stream samples. Nearly half of all the analyzed pesticides were not detected in any sample. Of the 45 pesticides that were detected at least once, the median concentrations of 39 of the pesticides were less than the detection limit for the individual compounds, indicating that for at least 50 percent of the samples collected, those pesticides were not detected. Only 10 (less than 0.025 percent) of the measured concentrations exceeded any established drinking-water standards; 25 concentrations exceeded 2 mg/L (micrograms per liter) and 55 concentrations exceeded 1 mg/L. None of the elevated concentrations were measured in samples collected from streams that are used for public drinking-water supplies, and 8 of the 10 were measured in storm-affected samples. The timing and rate of agricultural pesticide applications affect the seasonal and areal concentration patterns of atrazine, simazine, chlorpyrifos, and diazinon observed in water from wells and streams in the Lower Susquehanna River Basin. Average annual pesticide use for agricultural purposes and nonagricultural pesticide use indicators were used to explain seasonal and areal patterns. Elevated concentrations of some pesticides in streams during base-flow and storm-affected conditions were related to the seasonality of agricultural-use applications and local climate conditions. Agricultural-use patterns affected areal concentration patterns for the high-use pesticides, but indicators of nonagricultural use were needed to explain concentration patterns of pesticides with smaller amounts used for agricultural purposes. Bedrock type influences the movement and discharge of ground water, which in turn affects concentration patterns of pesticides. The ratio of atrazine concentrations in stream base flow to concentrations in shallow wells varied among the different general rock types found in the Lower Susquehanna River Basin. Median concentrations of atrazine in well water and stream base flow tended to be similar in individual areas underlain by carbonate bedrock, indicating the connectivity of water in streams and shallow wells in these areas. In areas underlain by noncarbonate bedrock, median concentrations of atrazine tended to be significantly higher in stream base flow than in well water. This suggests a deep ground-water system that delivers water to shallow wells and a near-surficial system that supplies base-flow water to streams. In addition to the presence or absence of carbonate bedrock, pesticide leaching potential and persistence, soil infiltration capacity, and agricultural land use affected areal patterns in detection frequency and concentration differences between samples collected from streams during base-flow conditions and shallow wells.

Water-Resources Investigations Report↗

USGS1998

Water-quality assessment of part of the upper Mississippi River Basin, Minnesota and Wisconsin— Ground-water quality in the Prairie du Chien-Jordan aquifer, 1996

The Prairie du Chien-Jordan (PDCJ) aquifer (Prairie du Chien-Trempealeau aquifer in Wisconsin), composed of dolomite and sandstone of Cambrian to Ordovician age, is the principal bedrock aquifer in the Upper Mississippi River study unit of the National Water-Quality Assessment (NAWQA) Program. The aquifer supplies approximately 75 percent of the ground water withdrawn in the area. In certain areas, the aquifer is overlain by bedrock or glacial deposits having low hydraulic conductivity (termed "confined portion" of the aquifer in this report). In other areas the aquifer is overlain by glacial sand and gravel deposits having greater hydraulic conductivity (termed "unconfined portion" of the aquifer in this report). Differences in the hydrogeologic characteristics of these overlying units have potential to affect the downward movement of water and of contaminants into the aquifer from the land surface. Ground-water samples were collected from 50 domestic wells completed in this aquifer in July, August, and September of 1996 as part of the U.S. Geological Survey's National WaterQuality Assessment Program. The purpose of this report is to describe the chemical characteristics of water in the PDCJ aquifer and to summarize the differences in water quality in confined and unconfined portions of the aquifer. Twenty-five wells were sampled in each portion of the aquifer. Water samples from the wells were measured for physical parameters and analyzed for concentrations of major ions, nutrients, dissolved organic carbon, trace metals, radon, tritium, pesticides, and volatile organic compounds. Differences in anthropogenic and naturally occurring materials in water between confined and unconfined portions of the PDCJ aquifer are small and frequently the differences are not statistically significant at the 95 percent confidence level. Dissolved oxygen concentrations were slightly less and specific conductances and alkalinities were slightly greater in water in the confined portion of the aquifer. Only the differences in specific conductance and alkalinity, however, were statistically significant at the 95 percent confidence level (two sample t-test). Concentrations of most major ions were generally greater in water from the confined portion of the aquifer. Nitrate (nitrite plus nitrate as N) and phosphorus were generally greater in the unconfined portion of the PDCJ aquifer although the differences were not statistically significant at the 95 percent confidence level (nonparametric Mann-Whitney test). In the confined portion of the aquifer no samples exceeded the maximum contaminant level of 10 milligrams per liter for nitrate. In the unconfined portion of the aquifer nitrate in two samples exceeded the maximum contaminant level of 10 milligrams per liter. Phosphorus concentrations were generally about an order of magnitude less than nitrate concentrations. Iron and manganese concentrations commonly exceeded the secondary maximum contaminant levels set by the U.S. Environmental Protection Agency and were generally greater in the confined portion of the PDCJ aquifer, although the differences were not statistically significant at the 95 percent confidence level (nonparametric Mann-Whitney test). Radon concentrations were greater in the confined portion of the aquifer than in the unconfined portion, although the difference was not statistically significant at the 95 percent confidence level (two sample t-test), with medians of 500 and 340 picoCuries per liter, respectively. Sixty-six percent of the radon concentrations were greater than the suspended maximum contaminant level of 300 picoCuries per liter. Tritium concentrations indicate that water in the unconfined portion of the PDCJ aquifer may have been recharged more recently than water in the confined portion of the aquifer, although differences in tritium concentrations between confined and unconfined portions of the aquifer were not statistically significant at the 95 percent confidence level (nonparametric MannWhitney test). Atrazine and its metabolite, deethylatrazine, were the most frequently detected pesticide compounds in water samples from the PDCJ aquifer. Volatile organic compounds were detected in 41 of the 50 water samples, but none of the concentrations exceeded 1 microgram per liter. Concentrations of volatile organic compounds were slightly greater in the unconfined portion, although the differences in detection rates were not statistically significant at the 95 percent confidence level (nonparametric Mann-Whitney test). Carbon disulfide and methyl chloride were the most frequently detected volatile organic compounds. Water in the unconfined portion of the PDCJ aquifer in Minnesota and Wisconsin appears to be affected to a greater degree by anthropogenic activities than water in the confined portion of the aquifer. Water in the confined portion has a longer residence time and greater concentrations of dissolution products of minerals. In general, however, differences in anthropogenic and naturally occurring materials among confined and unconfined portions of the aquifer are small and frequently not significantly different.

Minnesota, Wisconsin↗

USGS1989

Sediment transport and accretion and the hydrologic environment of Grove Creek near Kenansville, North Carolina

The Grove Creek basin includes an area of about 42 square miles in Duplin County, southeastern North Carolina. This report evaluates sediment transport and sediment-accretion rates in the lowermost 9-mile reach of Grove Creek by using hydrologic, dendrologic, and radioisotopic data collected at seven sites along the study reach. Hydrologic data indicate two discharge frequencies. In the swampiest reaches downstream of site 5, inundation occurs 35 percent of the time; above this site, inundation occurs about 15 percent of the time. For the period from October 1982 through September 1987, overbank flows at site 4 occurred 82 times and lasted a total of 632 days with a maximum duration of 3 months. Distribution of tree species indicates that water-tolerant bald cypress have developed along the lowermost 7 miles of Grove Creek where the flood plain is inundated 35 percent of the time. These swampy conditions have been in existence across limited parts of the flood plain for the last 80 to 150 years. In contrast, the upstream sites have been comparatively dry for the same period. The sediment that is transported in Grove Creek is predominately silt and clay. Measured suspended-sediment concentrations at discharges less than 100 cubic foot per second are less than 15 milligrams per liter; concentrations at higher discharges did not exceed 67 milligrams per liter. Calculated suspended-sediment loads ranged from 75 to 444 tons per year at the various data-collection sites on Grove Creek. Sediment-accretion rates estimated from dendrologic data ranged from 0.03 foot per year to 0.06 foot per year. The highest accretion rates occur in the downstream swampy reaches and are due to channel braiding, low channel gradients and flow velocities, and high frequency and duration percentages of overbank flow, which result in the deposition of clay and silt over wide areas of the flood plain. Sediment-accretion rates along Grove Creek were also estimated by radioisotope methods. Sediment cores from the flood plain showed detectable levels of cesium-137, lead-210, and radium-226. Cesium-137 was not present in the sediment cores below a depth of 10 inches; this indicates a maximum accretion rate of about 0.024 foot per year for the period 1952-87. Lead-210 and radium-226 data from these same sediment cores indicate an average accretion rate of 0.026 foot per year to a depth of about 2 feet. The maximum age of the flood-plain sediment at the 2-foot level is about 80 years. The atmosphere was confirmed as the source of excess lead-210 in flood-plain sediments by nearly matching calculated values of the lead-210 flux at each site with the measured value for atmospheric deposition.

North Carolina↗

USGS1995

Statistical characteristics of stream discharge in tributaries of selected estuaries in southern New Jersey

This report presents the results of a study, done in cooperation with the New Jersey Department of Environmental Protection, to analyze the characteristics of stream discharge for tributaries of the estuaries of the Metedeconk, Toms, Great Egg Harbor, Tuckahoe, and Maurice Rivers. The following statistics were calculated for selected streamflow-gaging stations: (1) mean annual and mean monthly discharge, and (2) lowest annual 7-day mean discharge for selected recurrence intervals.Values of lowest annual 7-day mean discharge were calculated for the entire year and for the 3-, 4-, 5-, and 6-month periods of greatest tributary discharge. The monthly variation in discharge was examined. Values of discharge at different stations were converted to runoff and compared; runoff is expressed as discharge per unit area of drainage for a given period. Tests for trend were conducted on values of monthly discharge and lowest annual discharges at continuous-record stations. Statistics were determined from discharge records of the U.S. Geological Survey. The monthly variation in discharge is similar for most streams in the study area; discharge is greatest during March and April and least during August, September, and October. The 3-, 4-, 5-, and 6-month periods of greatest discharge are February through April, January through April, January through May, and December through May, respectively. Mean annual runoff is greater in the tributaries of the Metedeconk and Toms River estuaries than in the tributaries of the other estuaries. Runoff in tributaries of these two basins ranges from 24 to 29 inches per year; the corresponding range for tributaries of the other estuaries is 16 to 23 inches per year. Trend analysis showed that values of lowest annual discharges at continuous-record stations on tributaries of all five estuaries decreased during water years 1970-89. For four stations, values of 183-day lowest annual discharge during the complete year decreased; for three of lowest annual 7- or 30-day mean discharge during the 3-, 4-, 5-, and 6-month periods of greatest discharge decreased. There were no trends in monthly discharge for water years 1970-89. For other periods tested, there were no trends either in lowest annual discharges or monthly discharges. Discharge statistics at the heads of tide were calculated from the period-of-record characteristics at continuous-record stations and characteristics determined for partial-record stations. Results show that discharge at the heads of tide of the estuaries is directly related to the drainage area.Drainage areas and discharge are greatest for the Great Egg Harbor and Maurice Rivers, whose mean annual discharges are 340 and 310 cubic feet per second, respectively. Mean annual discharges of the Toms and Metedeconk Rivers are 220 and 140 cubic feet per second, respectively. Drainage area and discharge of the Tuckahoe River are the smallest of the estuaries studied; mean annual discharge is 43.9 cubic feet per second.

New Jersey↗

USGS2000

Laboratory performance in the Sediment Laboratory Quality-Assurance Project, 1996-98

This report describes the results of the first 3 years of an ongoing study of sediment laboratories used by the U.S. Geological Survey (USGS). The sediment laboratories currently in operation constitute the entire USGS national laboratory system for sediment analyses. As with all environmental data, physical sediment data can be expected to contain a certain amount of difference, whether the difference resulted from the collecting, transporting, or analyzing of the sample. Because it is important to know how each laboratory is performing, the USGS initiated the Sediment Laboratory Quality-Assurance (SLQA) project in August 1996. From August 1996 through June 1998, five studies were made, the results of which are the basis of this report. The focus of the project is on quantitative analyses done on water-sediment mixtures to derive suspended-sediment concentrations, sediment-mass determinations, and sand/fine separations. For the purpose of this report, all mass determinations are net values—the tare weight of the container is excluded. The fine-size material is defined as particles sieved to a size of less than 62 micrometers (µm) and sand-size material is defined as particles sieved to a size of between 63 and 125 µm. Also, in this report, class 1 samples are defined as samples containing 50 to 100 milligrams (mg) of fine-size material, class 2 samples are defined as samples containing 101 to 300 mg of fine-size material, and class 3 samples are defined as samples containing 2,200 to 3,200 mg of fine-size material. In studies 96-1 through 98-1, the amount of sand added to each sample ranged from 9 to 28 percent of the mass of fine-size material in each sample class. Analytical results from all sediment quality-control samples are compiled and statistically summarized by the USGS, Branch of Quality Systems, both on an intra- and interlaboratory basis. When evaluating these data, the reader needs to keep in mind that every measurement has an error component associated with it. It is premature to use the data from the first five SLQA studies to judge any of the laboratories as performing in an unacceptable manner. There were, however, some notable differences in the results for the 12 laboratories that participated in the five SLQA studies. For example, the overall median percent difference for suspended-sediment concentration on an individual laboratory basis ranged from –18.04 to –0.33 percent. Five of the 12 laboratories had an overall median percent difference for suspended-sediment concentration of –2.02 to –0.33 percent. There was less variability in the median difference for the measured fine-size material mass. The overall median percent difference for fine-size material mass ranged from –10.11 to –4.27 percent. Except for one laboratory, the median difference for fine-size material mass was within a fairly narrow range of –6.76 to –4.27 percent. The median percent difference for sand-size material mass differed among laboratories more than any other physical sediment property measured in the study. The overall median percent difference for the sand-size material mass ranged from –1.49 percent to 26.39 percent. Five of the nine laboratories that do sand/fine separations had overall median percent differences that ranged from –1.49 to 2.98 percent for sand-size material mass. Careful review of the data reveals that certain laboratories consistently produced data within statistical control limits for some or all of the physical sediment properties measured in this study, whereas other laboratories occasionally produced data that exceeded the control limits.

Water-Resources Investigations Report↗

USGS1996

Variations in surface-water quantity and quality as a result of the 1993 summer flood in the Devils Lake basin, North Dakota

Greater-than-normal precipitation during the summer of 1993 affected the hydrologic response and surface-water quality in the Devils Lake Basin. Large areas in the basin were flooded as a result of the precipitation, and water from these areas drained slowly through the chain of lakes into Devils Lake. This report summarizes the results of surface-water quantity and quality monitoring designed to document the effects of flooding in the Devils Lake Basin. Specific objectives are (1) to document the quantity and quality of streamflow in the Devils Lake Basin immediately before, during, and after the 1993 flood and (2) to document the hydrologic and chemical changes in the upstream chain of lakes and in Devils Lake during April through October 1993. Precipitation during June through August ranged from about 17 inches in the Mauvais Coulee subbasin to about 21.4 inches in the Edmore Coulee subbasin. Streamflow measured for Edmore Coulee Tributary indicated that 12.2 inches of runoff occurred during April through October 1993. This is one of the greatest runoffs in North Dakota for which records are available. During April through September, the cumulative volume of inflow to the chain of lakes was about 8 percent of the cumulative volume of rainfall and the measured cumulative volume of outflow from the chain of lakes was about 7 percent of the cumulative volume of rainfall. The cumulative volume of water stored in the chain of lakes increased from 6,350 acre-feet in April to 82,300 acre-feet in August and then decreased to 24,400 acre-feet in October. Devils Lake rose from 1,423.0 feet above sea level on June 10 to 1,427.0 feet above sea level on September 28, largely in response to direct precipitation on the lake. Nutrient concentrations for coulees that flow into the chain of lakes generally were at a maximum during the spring and a minimum during the late summer and fall. About 37 percent of the dissolved-solids load and about 43 percent of the total ammonia plus organic nitrogen load was attributed to Edmore Coulee Tributary. Between May and October, increases in the total ammonia plus organic nitrogen mass for the chain of lakes ranged from about 39 to 133 percent. Increases in the total phosphorus mass ranged from about 43 to 157 percent. Decreases in dissolved-solids concentrations from May to early August ranged from about 77 percent in Sixmile Bay to about 9 percent in Main Bay, Creel Bay, and East Devils Lake. Decreases in the dissolved-solids concentrations in Devils Lake and East Devils Lake may have been the result of dilution by direct precipitation. However, during the same period, dissolvedsolids concentrations increased about 6 percent in East Bay. Between May and October, the dissolved-solids mass for Devils Lake and East Devils Lake increased 500 million kilograms. Only about 25 percent of the increase can be attributed to streamflow. The total ammonia plus organic nitrogen mass for Devils Lake and East Devils Lake increased about 38 percent between May and October, and the total phosphorus mass increased about 79 percent.

Water-Resources Investigations Report↗

USGS2000

Contaminant trends in sport fish from Lake Roosevelt and the upper Columbia River, Washington, 1994-1998

Fish from Lake Roosevelt were first reported to contain elevated concentrations of contaminants in the early 1980?s, with mercury, dioxins and furans, and polychlorinated biphenyls (PCBs) identified as being of most concern to human health. Over the following years there were a series of studies by United States and Canadian agencies addressing contaminants in fish from both a human and environmental perspective. In the early 1990?s, industrial discharges to the Columbia River above the international boundary decreased. The dominant changes in industrial practices included a reduction in slag and effluent discharges from a lead-zinc smelter, and a reduction in dioxins and furans due to processing changes at a Canadian pulp mill. It is believed that these two alterations in industrial practices may have greatly reduced the loading of selected contaminants to the Columbia River system. In response to these recent changes, the U.S. Geological Survey initiated this present study for the purpose of determining the present concentrations of mercury, dioxins and furans, and PCBs in fish, and, if possible, to determine if concentrations have changed since the 1994 studies. All contaminant analysis was done on fish fillets in order to address human health concerns. Our study concluded that the concentrations of contaminants in fish that were identified as a potential threat to human health have either not changed since the 1994 studies, or have decreased. PCBs, as determined by Aroclor 1254, do not appear to have changed between 1994 and 1998; sources of PCBs are presently unknown. In contrast, dioxins and furans, as indicated by 2,3,7,8-TCDF, did show a significant decrease in rainbow trout fillets from 1994 to 1998. However, there was no apparent change in the average 2,3,7,8-TCDF concentrations in mountain whitefish, with the reason uncertain at this time. Average concentrations of 2,3,7,8-TCDF were higher in mountain whitefish than in rainbow trout. Toxicity equivalence concentrations (TEC) are determined by summing the relative toxicity of individual congeners of dioxins, furans, and toxic ?dioxin-like? PCB congeners in individual fish. Rainbow trout from the upper reach have higher TECs than rainbow trout from the lower reach, with trout from the upper reach having a higher percentage of the toxicity from toxic ?dioxin-like? PCBs than dioxin and furan compounds. In relation to mercury, the concentrations of total mercury in walleye have significantly decreased by about 50 percent from 1994 to 1998.

Water-Resources Investigations Report↗

USGS1995

Analysis of steady-state flow and advective transport in the eastern Snake River Plain aquifer system, Idaho

Quantitative estimates of ground-water flow directions and traveltimes for advective flow were developed for the regional aquifer system of the eastern Snake River Plain, Idaho. The work included: (1) descriptions of compartments in the aquifer that function as intermediate and regional flow systems, (2) descriptions of pathlines for flow originating at or near the water table, and (3) quantitative estimates of traveltimes for advective transport originating at or near the water table. A particle-tracking postprocessing program was used to compute pathlines on the basis of output from an existing three-dimensional steady-state flow model. The flow model uses 1980 conditions to approximate average annual conditions for 1950-80. The advective transport model required additional information about the nature of flow across model boundaries, aquifer thickness, and porosity. Porosity of two types of basalt strata has been reported for more than 1,500 individual cores from test holes, wells, and outcrops near the south side of the Idaho National Engineering Laboratory. The central 80 percent of samples had porosities of 0.08 to 0.25, the central 50 percent of samples, O. 11 to 0.21. Calibration of the model involved choosing a value for porosity that yielded the best solution. Two radiologic contaminants, iodine-129 and tritium, both introduced to the flow system about 40 years ago, are relatively conservative tracers. Iodine- 129 was considered to be more useful because of a lower analytical detection limit, longer half-life, and longer flow path. The calibration value for porosity was 0.21. Most flow in the aquifer is contained within a regional-scale compartment and follows paths that discharge to the Snake River downstream from Milner Dam. Two intermediate-scale compartments exist along the southeast side of the aquifer and near Mud Lake.One intermediate-scale compartment along the southeast side of the aquifer discharges to the Snake River near American Fails Reservoir and covers an area of nearly 1,000 square miles. This compartment, which receives recharge from an area of intensive surface-water irrigation, is apparently fairly stable. The other intermediate-scale compartment near Mud Lake covers an area of 300 square miles. The stability and size of this compartment are uncertain, but are assumed to be in a state of change. Traveltimes for advective flow from the water table to discharge points in the regional compartment ranged from 12 to 350 years for 80 percent of the particles; in the intermediate-scale flow compartment near American Falls Reservoir, from 7 to 60 years for 80 percent of the particles; and in the intermediate-scale compartment near Mud Lake, from 25 to 100 years for 80 percent of the particles. Traveltimes are sensitive to porosity and assumptions regarding the importance of the strength of internal sinks, which represent ground-water pumpage. A decrease in porosity results in shorter traveltimes but not a uniform decrease in traveltime, because the porosity and thickness is different in each model layer. Most flow was horizontal and occurred in the top 500 feet of the aquifer. An important limitation of the model is the assumption of steady-state flow. The most recent trend in the flow system has been a decrease in recharge since 1987 because of an extended drought and changes in land use. A decrease in flow through the system will result in longer traveltimes than those predicted for a greater flow. Because the interpretation of the model was limited to flow on a larger scale, and did not consider individual wells or well fields, the interpretations were not seriously limited by the discretization of well discharge. The interpretations made from this model also were limited by the discretization of the major discharge areas. Near discharge areas, pathlines might not be representative at the resolution of the grid. Most improvement in the estimates of ground-waterflow directions and travelt

Water-Resources Investigations Report↗

USGS1986

Shallow ground-water conditions, Tom Green County, Texas

Most of the water needs of Tom Green County, Texas, are supplied by ground water; however, the city of San Angelo is supplied by surface water. Groundwater withdrawals during 1980 (latest year for which data are available) in Tom Green County totaled about 15,300 acre-feet, all derived from shallow aquifers. Shallow aquifers in this report refer to the ground-water system generally less than 400 feet deep that contains water with less than a 10,000 milligrams per liter concentration of dissolved solids; aquifers comprising this system include: The Leona, Comanche Peak, Trinity, Blaine, San Angelo, Choza, Bullwagon, Vale, Standpipe, and Arroyo aquifers. The current (1983) water levels in shallow aquifers in Tom Green County are relatively unchanged from those levels listed in previous reports. In most wells, the change in water level is less than 10 feet, and only a few isolated wells or areas have changes of more than 20 feet. Based on long-term hydrographs of selected wells and precipitation, water levels are directly related to precipitation and associated pumpage for irrigation. Current (1983) water levels probably are higher than normal due to the above-normal precipitation during 1980-81. Ground water in Tom Green County commonly is very hard (greater than 180 milligrams per liter as calcium carbonate), and chemical types vary in the aquifers and in different parts of the county. The concentrations of dissolved solids range from 200 to 3,000 milligrams per liter, the dissolved-chloride concentrations range from about 40 to 1,000 milligrams per liter, and the dissolved-sulfate concentrations normally range from about 25 to 600 milligrams per liter. The dissolved-nitrate concentrations in samples from eight wells ranged from 2 to 37 milligrams per liter. Five of these samples exceeded the maximum contaminant level of 10 milligrams per liter set by the U.S. Environmental Protection Agency. Of the eight water samples analyzed for minor elements, two exceeded the maximum contaminant level for selenium, and one exceeded the maximum contaminant level for manganese. Samples from three wells were analyzed for selected pesticides; no pesticides were detected. Two groups of ground-water samples were tested for bacteria in April and August 1983. The first group consisted of samples from 25 wells; no samples contained fecal-coliform bacteria, but 15 samples contained fecal-streptococci bacteria. The second group consisted of samples from 29 wells and 1 spring; twelve of these samples contained fecal-coliform bacteria and all 30 contained fecal-streptococci bacteria. Water samples from seven wells were common to both groups, and the samples tested in August contained more bacteria. Counts of fecal-coliform bacteria ranged from 0 to 26 colonies per 100 milliliters with most less than 5 colonies per 100 milliliters. Counts of fecal-streptococci bacteria ranged from 0 to 400 colonies per 100 milliliters with most less than 20 colonies per 100 milliliters. The presence of fecal-coliform and fecalstreptococci bacteria in water is only an indicator that pollution from septic systems may be present and is not a positive check for fecal pollution. Generally, the aquifers are not contaminated by septic-system effluent, however, some individual wells or localized areas could be contaminated by nearby septic systems. Using dissolved-solids concentrations as an indicator, historical and current (1983) water-quality records were compared to determine if any changes in water quality had occurred. The quality of water from Cretaceous rocks underlying the Edwards Pleateau has not changed significantly; this water is the least mineralized ground water in the county. The quality of water from the Arroyo and Bullwagon aquifers in the eastern most part of the county also has not changed significantly; dissolved-solids concentrations range from 1,500 to 2,000 milligrams per liter. In the remainder of the county, dissolved-solids concentrations have increased from 10 to 500 milligrams per liter in ground water along the river valleys and in the Li pan Flat area and increases of 500 to 1,100 milligrams per liter have occurred in ground water southeast of San Angelo, west of Twin Buttes Reservoir, and about 10 miles east of San Angelo. Locally, dissolved-solids concentrations have increased by as much as 4,530 milligrams per liter in water from individual wells. Pollution from oil-field activities may affect the quality of water in some isolated wells and in some areas in the county. No historical records are available for determining any changes in pesticides, minor elements, or bacteria.

Texas↗

USGS2003

Simulation of net infiltration and potential recharge using a distributed-parameter watershed model of the Death Valley region, Nevada and California

This report presents the development and application of the distributed-parameter watershed model, INFILv3, for estimating the temporal and spatial distribution of net infiltration and potential recharge in the Death Valley region, Nevada and California. The estimates of net infiltration quantify the downward drainage of water across the lower boundary of the root zone and are used to indicate potential recharge under variable climate conditions and drainage basin characteristics. Spatial variability in recharge in the Death Valley region likely is high owing to large differences in precipitation, potential evapotranspiration, bedrock permeability, soil thickness, vegetation characteristics, and contributions to recharge along active stream channels. The quantity and spatial distribution of recharge representing the effects of variable climatic conditions and drainage basin characteristics on recharge are needed to reduce uncertainty in modeling ground-water flow. The U.S. Geological Survey, in cooperation with the Department of Energy, developed a regional saturated-zone ground-water flow model of the Death Valley regional ground-water flow system to help evaluate the current hydrogeologic system and the potential effects of natural or human-induced changes. Although previous estimates of recharge have been made for most areas of the Death Valley region, including the area defined by the boundary of the Death Valley regional ground-water flow system, the uncertainty of these estimates is high, and the spatial and temporal variability of the recharge in these basins has not been quantified. To estimate the magnitude and distribution of potential recharge in response to variable climate and spatially varying drainage basin characteristics, the INFILv3 model uses a daily water-balance model of the root zone with a primarily deterministic representation of the processes controlling net infiltration and potential recharge. The daily water balance includes precipitation (as either rain or snow), snow accumulation, sublimation, snowmelt, infiltration into the root zone, evapotranspiration, drainage, water content change throughout the root-zone profile (represented as a 6-layered system), runoff (defined as excess rainfall and snowmelt) and surface water run-on (defined as runoff that is routed downstream), and net infiltration (simulated as drainage from the bottom root-zone layer). Potential evapotranspiration is simulated using an hourly solar radiation model to simulate daily net radiation, and daily evapotranspiration is simulated as an empirical function of root zone water content and potential evapotranspiration. The model uses daily climate records of precipitation and air temperature from a regionally distributed network of 132 climate stations and a spatially distributed representation of drainage basin characteristics defined by topography, geology, soils, and vegetation to simulate daily net infiltration at all locations, including stream channels with intermittent streamflow in response to runoff from rain and snowmelt. The temporal distribution of daily, monthly, and annual net infiltration can be used to evaluate the potential effect of future climatic conditions on potential recharge. The INFILv3 model inputs representing drainage basin characteristics were developed using a geographic information system (GIS) to define a set of spatially distributed input parameters uniquely assigned to each grid cell of the INFILv3 model grid. The model grid, which was defined by a digital elevation model (DEM) of the Death Valley region, consists of 1,252,418 model grid cells with a uniform grid cell dimension of 278.5 meters in the north-south and east-west directions. The elevation values from the DEM were used with monthly regression models developed from the daily climate data to estimate the spatial distribution of daily precipitation and air temperature. The elevation values were also used to simulate atmosp

Water-Resources Investigations Report↗

USGS1997

Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania: Hydrology of a small carbonate site near Ephrata, Pennsylvania, prior to implementation of nutrient management

The U.S. Geological Survey, in cooperation with the U.S. Department of Agriculture and Pennsylvania Department of Environmental Protection, investigated the effects of agricultural best-management practices on water quality in the Conestoga River headwaters watershed. This report describes environmental factors and the surface-water and ground-water quality of one 47.5-acre field site, Field-Site 2, from October 1984 through September 1986, prior to implementation of nutrient management. The site is partially terraced agricultural cropland underlain by carbonate rock. Twenty-seven acres are terraced, pipe-drained, and are under no-till cultivation. The remaining acreage is under minimum-till cultivation. Corn is the primary crop. The average annual rate of fertilization at the site was 480 pounds per acre of nitrogen and 110 pounds per acre of phosphorus. An unconfined limestone and dolomitic aquifer underlies the site, Depth to bedrock ranges from 5 to 30 feet below land surface. Estimated specific yields range from 0.05 to 0.10, specific capacities of wells range from less than 1 to about 20 gallons per minute per foot of drawdown, and estimates of transmissivities range from 10 to 10,000 square feet per day. Average ground-water recharge was estimated to be about 23 inches per year. The specific capacity and transmissivity data indicate that two aquifer regimes are present at the site. Wells drilled into dolomites in the eastern part of the site have larger specific capacities (averaging 20 gallons per minute per foot of drawdown) relative to specific capacities (averaging less than 1 gallon per minute per foot of drawdown) of wells drilled into limestones in the western part of the site. Median concentrations of soil-soluble nitrate and soluble phosphorus in the top 4 feet of silt- or silty-clay-loam soil ranged from 177 to 329 and 8.5 to 35 pounds per acre, respectively. Measured runoff from the pipe-drained terraces ranged from 10 to 48,000 cubic feet and was 1.7 and 0.8 percent, respectively, of the 1985 and 1986 annual precipitation. An estimated 90,700 cubic feet of surface runoff carried 87 pounds to total nitrogen and 37 pounds of total phosphorus, or less that 0.65 percent of the amount of either nutrient applied during the study period. Rainfall on the snow-covered, frozen ground produced more that half of the runoff and nitrogen and phosphorus loads measured in pipe-drained runoff. Graphical and regression analyses of surface runoff suggest that (1) mean-storm concentrations of total nitrogen species and total phosphorus decreased with increasing time between a runoff event and the last previous nutrient application, and (2) mean total-phosphorus concentrations approached a baseline value (estimated at 2 to 5 milligrams per liter for total-phosphorus concentrations) after several months without nutrient applications. Dissolved nitrate concentrations in ground water in wells unaffected by an on-site ammonia spill ranged from 7.4 to 100 milligrams per liter. Average annual additions and removals of nitrogen were estimated. Nitrogen was added to the site by applications of manure and commercial fertilizer nitrogen, as well as by precipitation and ground water entering across the western site boundary. These sources of nitrogen accounted for 95, 3, 1, and 1 percent, respectively, of estimated additions. Nitrogen was removed from the site in harvested crops, by ground-water discharge, by volatilization, and in surface runoff, which accounted for 42, 28, 29, and less than 1 percent, respectively, of estimated removals.

Pennsylvania↗

USGS2004

Characterization of aquifer heterogeneity using cyclostratigraphy and geophysical methods in the upper part of the Karstic Biscayne Aquifer, Southeastern Florida

This report identifies and characterizes candidate ground-water flow zones in the upper part of the shallow, eogenetic karst limestone of the Biscayne aquifer in the Lake Belt area of north-central Miami-Dade County using cyclostratigraphy, ground-penetrating radar (GPR), borehole geophysical logs, and continuously drilled cores. About 60 miles of GPR profiles were used to calculate depths to shallow geologic contacts and hydrogeologic units, image karst features, and produce qualitative views of the porosity distribution. Descriptions of the lithology, rock fabrics, and cyclostratigraphy, and interpretation of depositional environments of 50 test coreholes were linked to the geophysical interpretations to provide an accurate hydrogeologic framework. Molluscan and benthic foraminiferal paleontologic constraints guided interpretation of depositional environments represented by rockfabric facies. Digital borehole images were used to characterize and quantify large-scale vuggy porosity. Preliminary heat-pulse flowmeter data were coupled with the digital borehole image data to identify candidate ground-water flow zones. Combined results show that the porosity and permeability of the karst limestone of the Biscayne aquifer have a highly heterogeneous and anisotropic distribution that is mostly related to secondary porosity overprinting vertical stacking of rock-fabric facies within high-frequency cycles (HFCs). This distribution of porosity produces a dual-porosity system consisting of diffuse-carbonate and conduit flow zones. The nonuniform ground-water flow in the upper part of the Biscayne aquifer is mostly localized through secondary permeability, the result of solution-enlarged carbonate grains, depositional textures, bedding planes, cracks, root molds, and paleokarst surfaces. Many of the resulting pore types are classified as touching vugs. GPR, borehole geophysical logs, and whole-core analyses show that there is an empirical relation between formation porosity, permeability, formation electrical conductivity, and GPR reflection amplitudes? as porosity and permeability increase, formation electrical conductivity increases and reflection amplitude decreases. This relation was observed throughout the entire vertical and lateral section of the upper part of the Biscayne aquifer in the study area. Further, upward-shallowing brackish- or freshwatercapped cycles of the upper part of the Fort Thompson Formation show low-amplitude reflections near their base that correspond to relatively higher porosity and permeability. This distribution is related to a systematic vertical stacking of rock-fabric facies within the cycle. Inferred flow characteristics of the porosity distribution within the upper part of the Biscayne aquifer were used to identify four ground-water flow classes, with each characterized by a discrete pore system that affects vertical and horizontal groundwater flow: (1) a low-permeability peat, muck, and marl ground-water flow class; (2) a horizontal conduit ground-water flow class; (3) a leaky, low-permeability ground-water flow class; and (4) a diffuse-carbonate ground-water flow class. At the top of the Biscayne aquifer, peat, muck, and marl can combine to form a relatively low-permeability layer of Holocene sediment that water moves through slowly. Most horizontal conduit flow is inferred to occur along touching vugs in portions of the following rock-fabric facies: (1) touchingvug pelecypod floatstone and rudstone, (2) sandy touching-vug pelecypod floatstone and rudstone, (3) vuggy wackestone and packstone, (4) laminated peloid grainstone and packstone, (5) peloid grainstone and packstone, and (6) peloid wackestone and packstone. Gastropod floatstone and rudstone, mudstone and wackestone, and pedogenic limestone rock-fabric facies are the main hosts for leaky, low-permeability units.

Florida↗

USGS2000

Geothermal hydrology of Valles Caldera and the southwestern Jemez Mountains, New Mexico

The Jemez Mountains in north-central New Mexico are volcanic in origin and have a large central caldera known as Valles Caldera. The mountains contain the Valles geothermal system, which was investigated during 1970-82 as a source of geothermal energy. This report describes the geothermal hydrology of the Jemez Mountains and presents results of an earlier 1972-75 U.S. Geological Survey study of the area in light of more recent information. Several distinct types of thermal and nonthermal ground water are recognized in the Jemez Mountains. Two types of near-surface thermal water are in the caldera: thermal meteoric water and acid sulfate water. The principal reservoir of geothermal fluids is at depth under the central and western parts of the caldera. Nonthermal ground water in Valles Caldera occurs in diverse perched aquifers and deeper valley-fill aquifers. The geothermal reservoir is recharged by meteorically derived water that moves downward from the aquifers in the caldera fill to depths of 6,500 feet or more and at temperatures reaching about 330 degrees Celsius. The heated geothermal water rises convectively to depths of 2,000 feet or less and mixes with other ground water as it flows away from the geothermal reservoir. A vapor zone containing steam, carbon dioxide, and other gases exists above parts of the liquid-dominated geothermal zone. Two subsystems are generally recognized within the larger geothermal system: the Redondo Creek subsystem and the Sulphur Creek subsystem. The permeability in the Redondo Creek subsystem is controlled by stratigraphy and fault-related structures. Most of the permeability is in the high-angle, normal faults and associated fractures that form the Redondo Creek Graben. Faults and related fractures control the flow of thermal fluids in the subsystem, which is bounded by high-angle faults. The Redondo Creek subsystem has been more extensively studied than other parts of the system. The Sulphur Springs subsystem is not as well defined. The upper vapor-dominated zone in the Sulphur Creek subsystem is separated from the liquid-dominated zone by about 800 feet of sealed caldera-fill rock. Acid springs occur at the top of the vapor zone in the Sulphur Springs area. Some more highly permeable zones within the geothermal reservoir are interconnected, but the lack of interference effects among some wells during production tests suggests effective hydraulic separation along some subsystem boundaries. Chemical and thermal evidence suggests that the Sulphur Springs subsystem may be isolated from the Redondo Creek subsystem and each may have its own zone of upflow and lateral outflow. The area of the entire geothermal reservoir is estimated to be about 12 to 15 square miles; its western limit generally is thought to be at the ring-fracture zone of the caldera. The top of the reservoir is generally considered to be the bottom of a small- permeability 'caprock' that is about 2,000 to 3,000 feet below land surface. Estimated thicknesses to the bottom of the reservoir range from 2,000 to 6,000 feet. Reservoir temperatures measured in exploration wells range from 225 degrees Celsius just below the caprock to about 330 degrees Celsius in deeper drill holes. Pressures measured in exploration wells in the Redondo Creek area ranged from 450 to 1,850 pounds per square inch. Steam-producing zones have been encountered above the liquid- dominated zones in wells, but the extent of steam zones is not well defined. The reservoir contains a near-neutral, chloride-type water containing about 7,000 milligrams per liter dissolved solids. No thermal springs in the caldera have geochemical characteristics similar to those of the geothermal reservoir fluids sampled in wells. Oxygen-18 and deuterium isotope concentrations of geothermal reservoir fluid indicate a meteoric origin. The moat valleys in

Water-Resources Investigations Report↗

USGS1999

Traveltimes along Clear Creek and selected tributaries upstream from Golden, Colorado, 1996-97

Increased traffic along mountainous stretches of Interstate Highway 70, U.S. Highway 40, and U.S. Highway 6 in Colorado has resulted in a corresponding increase in the movement of hazardous materials. The proximity of Clear Creek and its tributaries to these highways places downstream water users at risk in the event of an accidental hazardous-material release. A traveltime study was performed on two reaches of Clear Creek and two of its tributaries to provide the necessary information to allow downstream water managers to protect water supplies in the event of a hazardous-material release. The information also can be used by hazardous-materialresponse teams to intercept contaminants as they move downstream. This report summarizes the methods and findings of the traveltime study. Traveltime measurements were made using rhodamine-WT dye as a tracer in two reaches of Clear Creek and two Clear Creek tributaries in Clear Creek and Jefferson Counties, Colorado. The reaches were Clear Creek from the town of Berthoud Falls to the city limits of Golden; Clear Creek from the eastern edge of the Loveland Basin Ski Area parking lot to the town of Georgetown; the headwaters of two Clear Creek tributaries near Loveland Pass to the Loveland Valley Ski Area; and two unnamed tributaries of Hoop Creek (a tributary of Clear Creek) near Berthoud Pass to the confluence with the West Fork of Clear Creek. Measurements were made at three times of the year to obtain data from different flow conditions. Traveltime and average velocities were determined for each stream reach. During high flow, dye-cloud leading-edge traveltimes ranged from about 0.6 hour along the Loveland Pass to the Loveland Valley Ski Area drainage to about 8.8 hours between Berthoud Falls and Golden. During low flow, leading-edge traveltimes ranged from about 2.6 hours along the same drainage from Loveland Pass to about 28.6 hours between Berthoud Falls and Golden. Average velocity between the Loveland Pass sites ranged from about 1.3 miles per hour during high flow to about 0.3 mile per hour during low flow. Average velocities between Berthoud Falls and Golden ranged from about 4.4 miles per hour during high flow to about 1.3 miles per hour during low flow. A curve-fitting program was used to fit Lorentz and Gaussian distributions to the data generated from the traveltime measurements. Because discrete (not continuous) traveltime measurements were made, an estimate of the actual time of the leading edge, peak, and trailing edge needed to be determined from the sample data. The curve-fitting program provided the means to calculate the timing of events (leading edge, peak, and trailing edge) that were not precisely measured. Calculated leading-edge, peak, and trailing-edge times were used to generate a series of graphs for each study reach. Traveltime estimation tables were generated from the data for a range of Clear Creek discharges. Because of the high variability of discharge within the basin, the Lawson surface-water gage located near the center of the basin was used as the reference location. Discharge measurements for the Lawson gage are available on the Internet, which can be accessed by most hazardous-material-team dispatchers. Traveltimes determined during the individual studies were plotted against the corresponding discharge at the reference location. A curve-fitting program was used to generate a series of curves, which were used to produce traveltime estimation tables.

Colorado↗

USGS1996

Water quality of the lower Columbia River Basin: Analysis of current and historical water-quality data through 1994

The lower Columbia River Basin includes the river basins draining into the Columbia River below Bonneville Dam—the largest of which is the Willamette River. This report presents the results of a study by the U.S. Geological Survey, done in cooperation with the Lower Columbia River Bi-State Water- Quality Program, to describe the water-quality conditions in the lower Columbia River Basin by interpreting historical data collected and data collected in 1994. Historical water-quality data spanning more than 50 years and comprising more than 200 parameters were collated for interpretation in this report. The U.S. Geological Survey, the Oregon Department of Environmental Quality, and the Washington Department of Ecology collected water-quality data at 10 sites in the lower Columbia River Basin from January to December of 1994. Water-quality constituents measured in 1994 were screened against U.S. Environmental Protection Agency (EPA) and State guidelines. Arsenic, a human carcinogen, was detected in 15 of 16 samples in the lower Columbia River, but was not detected in any of the sampled tributaries. All 15 arsenic detections had concentrations that exceeded both the EPA ambient water-quality criteria for the protection of human health and the EPA human-health advisories for drinking water. Chromium was detected at all four Columbia River sites—most frequently in the Columbia River at Hayden Island. None of the chromium concentrations detected, however, exceeded water-quality criteria or guidelines. Measurements of suspended trace-element concentrations (trace-element concentrations associated with the suspended-sediment fraction) showed that the suspended form is the dominant transport phase for aluminum, iron, and manganese, whereas the dissolved form is the dominant transport phase for arsenic, barium, chromium, and copper. On the basis of tributary loads during summer low-flow months, sources of suspended silver, nickel, aluminum, and antimony exist in the lower Columbia River Basin, whereas the sources of suspended zinc and arsenic exist outside of the lower basin. Twenty organic compounds were detected of the 47 compounds analyzed for this study. None of the organic compounds measured exceeded EPA’s ambient water-quality criteria or drinking-water guidelines. The Willamette River at Portland had the largest number of detections, and all 20 compounds were detected at one time or another at that site. The largest concentrations of the agricultural pesticides, atrazine, metolachlor, and simazine were detected in the Willamette River, where they were detected in 93, 86, 93 percent, respectively, of the samples collected. The highest concentrations of atrazine in the Willamette River were associated with the spring application and fall runoff periods. Both historical and current data showed that the highest water temperatures in the lower Columbia River Basin are present during August. For water years 1977–81 in the Columbia River at Bradwood (river mile 38.9), 75 percent of the daily mean water temperatures during August exceeded 20 degrees Celsius, a “special condition” criterion for the State of Washington. The special condition criterion was exceeded at four sites on the lower Columbia River during July and August, 1994—a period coinciding with season-high air temperatures and low streamflow. Trend tests using data from 1974 to 1994 showed significant (r < 0.05) upward trends for water temperature at the Columbia River at Warrendale and the Willamette River at Portland. Concentrations of dissolved oxygen and total dissolved gas were above saturation levels during high stormflows in the lower Columbia River and the Willamette River during 1994. The high concentrations of total dissolved gas in the Columbia River exceeded Oregon and Washington State standards of 110 percent of saturation and were caused by spilling water at the Columbia River dams. Aquatic life in the lower Columbia River Basin was not subjected to low dissolved-oxygen concentrations. Comparison of dissolved-oxygen concentrations in the Willamette River from 1949–58 to 1972–94 showed a significant increase in dissolved-oxygen concentrations during the low-streamflow months of summer. Trend tests showed significant (r < 0.05) downward trends from 1973 to 1994 for three constituents at the Columbia River at Warrendale: phosphorus in unfiltered water, total dissolved solids, and specific conductance. These trends may be a consequence of more conservative agricultural practices in the area upstream from Warrendale.

Oregon↗