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Map showing outcrops of ash-flow tuffs, Basin and Range Province and vicinity, Trans-Pecos Texas

This map report is one of a series of geologic and hydrologic maps covering all or parts of the States within the Basin and Range province of the western United States, resulting from work under the U.S. Geological Survey's program for geologic and hydrologic evaluation of the Basin and Range province to identify potentially suitable regions for future study relative to isolation of high-level nuclear waste (Bedinger, Sargent, and Reed, 1984) . The map report on the ash-flow tuffs of Trans-Pecos Texas was prepared from published maps and reports and from recent work in progress by geologists of the Texas Bureau of Economic Geology, and was compiled utilizing the project guidelines of Sargent and Bedinger (1984). The map shows the outcrops and localities of measured thicknesses of the ash-flow tuffs that resulted from silicic volcanism 38 to 28 million years ago (Henry and McDowell, 1982). Locally, however, some thin, inadequately studied tuffs of limited distribution have been excluded from the map. Such tuffs are reported in the "lower rhyolite" in the Eagle Mountains (Underwood, 1963), in the southern Davis Mountains (Parker, 1977), within parts of the Shely Group and Morita Ranch Formation in the Chinati Mountains (Cepeda and Henry, 1983) , and in the Rawls Formation in the Bofecillos Mountains (McKnight, 1969). The distribution of most ash-flow tuffs in the northern Davis and Wylie Mountains is not well known. The Chambers Tuff, largely tuffaceous sedimentary rocks, is reported to contain several ash-flow tuffs (Walton, 1972), but their distribution is poorly documented. Metamorphosed ash-flow tuffs of Precambrian age in the Thunderbird Group in the Franklin Mountains (Thomann, 1981) and in the Carrizo Mountain Group near Van Horn (Rudnick , 1983) were not included on the map. In some areas studied in reconnaissance, the definitive lithology of some volcanic units described as lava flows or tuffs has not been determined. In the Description of Map Units, the general location, caldera source and volume of tuff, isotopic age, if available, lithologic data, and the reference sources for each geologic unit are described. The nomenclature of the geologic units is from published reports and does not necessarily conform to U.S. Geological Survey usage.

Texas

Sediment-data sources and estimated annual suspended-sediment loads of rivers and streams in Colorado

Sources of sediment data collected by several government agencies through water year 1984 are summarized for Colorado. The U.S. Geological Survey has collected suspended-sediment data at 243 sites; these data are stored in the U.S. Geological Survey 's water data storage and retrieval system. The U.S. Forest Service has collected suspended-sediment and bedload data at an additional 225 sites, and most of these data are stored in the U.S. Environmental Protection Agency 's water-quality-control information system. Additional unpublished sediment data are in the possession of the collecting entities. Annual suspended-sediment loads were computed for 133 U.S. Geological Survey sediment-data-collection sites using the daily mean water-discharge/sediment-transport-curve method. Sediment-transport curves were derived for each site by one of three techniques: (1) Least-squares linear regression of all pairs of suspended-sediment and corresponding water-discharge data, (2) least-squares linear regression of data sets subdivided on the basis of hydrograph season; and (3) graphical fit to a logarithm-logarithm plot of data. The curve-fitting technique used for each site depended on site-specific characteristics. Sediment-data sources and estimates of annual loads of suspended, bed, and total sediment from several other reports also are summarized. (USGS)

Colorado

Aquatic macroinvertebrates collected at Ravenna Army Ammunition Plant, Portage and Trumbull Counties, Ohio, 1998

The results of a survey of macroinvertebrate communities in the Ravenna Army Ammunition Plant, were used as an indicator of disturbance in streams flowing through or near the training areas at the Plant. The data were interpreted using the Invertebrate Community Index (ICI), a multiple-metric index developed by the Ohio Environmental Protection Agency and based on the structural and functional characteristics of the macroinvertebrate community. Quantitative samples of the macroinvertebrate were collected for ICI determination from three streams South Fork Eagle Creek, Sand Creek, and Hinkley Creek flowing through the study area. These samples were collected using Hester-Dendy type artificial substrate samplers, which were placed in the streams during a 6-week sampling period, June 2 through July 15, 1998. A qualitative- dipnet sample from the natural substrates also was collected at each station on July 15, 1998, the last day of the sampling period. The macroinvertebrate communities at all three stations met the criterion designated for warmwater habitat aquatic life use, and communities at two of the three stations exceeded the criterion. The ICI scores were 42 at South Fork Eagle Creek, 50 at Sand Creek, and 48 at Hinkley Creek. The density of macroinvertebrates at South Fork Eagle Creek was 1,245 per square foot and represented 38 distinct taxa. The density at Sand Creek was 246 per square foot and represented 29 distinct taxa. The density at Hinkley Creek was 864 per square foot and represented 36 distinct taxa. Qualitative samples were also collected at 21 other sites using a D-framed dipnet. The qualitative sites encompassed three main environments: stream, pond, and swamp-wetland. All available habitat types in each environment were sampled until no new taxa were evident during coarse examination. The highest number of taxa were collected from the streams. The total number of taxa collected in streams ranged from 25 to 76; the mean was 60 and median 64. The total taxa collected from ponds ranged from 32 to 60; the mean was 42 and median 41. The total taxa collected from swamp-wetland areas ranged from 6 to 30; the mean was 20 and median 23. The results are listed in phylogenetic order in this report and establish baseline data for future studies.

Ohio

Water-resources investigations of the U.S. Geological Survey in the northern Great Plains coal region of Wyoming, Montana, and North Dakota, 1975

The Geological Survey's Water Resources Division has for many years maintained a program of water-resources investigations that includes the coal regions of Wyoming, Montana, and North Dakota. These programs have been supported by State and local agencies and by other agencies of the Federal government, largely to provide data for water-resources development projects, allocations of water, and to inventory of water resources for future planning. The recent interest in coal has added new dimensions and greater intensity to the investigations. The work has expanded to include monitoring the environmental effects of coal mining and processing and to determine the availability of additional water supplies for coal-conversion plants and related demands. New objectives are now reflected in the program. Much of the work is to assist the Bureau of Land Management in its responsibilities to minimize the possible detrimental effects of coal mining on the public resource lands. The Environmental Protection Agency also supports a significant part of the program. Their support is to assure that water-quality information is collected at key locations, with types of water-quality data and frequency of sampling needed by that agency in the discharge of its function. Relatively large increases in the program have been funded by direct appropriation to the Geological Survey. This report describes the water-resources investigation program that is currently in operation. Locations of gaging stations and water-quality measuring sites, frequencies and parameters, and areas of groundwater studies are included in this report. Brief descriptions of coal-related studies by investigators who are headquartered outside the Northern Great Plains coal regions are also included. Such studies are research in topics related to coal extraction, water supply, and post-mining reclamation

Montana, North Dakota, Wyoming

Recharge rates and aquifer hydraulic characteristics for selected drainage basins in middle and east Tennessee

Quantitative information concerning aquifer hydrologic and hydraulic characteristics is needed to manage the development of ground-water resources. These characteristics are poorly defined for the bedrock aquifers in Middle and East Tennessee where demand for water is increasing. This report presents estimates of recharge rate, storage coefficient, diffusivity, and transmissivity for representative drainage basins in Middle and East Tennessee, as determined from analyses of stream-aquifer interactions. The drainage basins have been grouped according to the underlying major aquifer, then statistical descriptions applied to each group, in order to define area1 distribution of these characteristics. Aquifer recharge rates are estimated for representative low, average, and high flow years for 63 drainage basins using hydrograph analysis techniques. Net annual recharge during average flow years for all basins ranges from 4.1 to 16.8 in/yr (inches per year), with a mean value of 7.3 in. In general, recharge rates are highest for basins underlain by the Blue Ridge aquifer (mean value11.7 in/yr) and lowest for basins underlain by the Central Basin aquifer (mean value 5.6 in/yr). Mean recharge values for the Cumberland Plateau, Highland Rim, and Valley and Ridge aquifers are 6.5, 7.4, and 6.6 in/yr, respectively. Gravity drainage characterizes ground-water flow in most surficial bedrock aquifer in Tennessee. Accordingly, a gravity yield analysis, which compares concurrent water-level and streamflow hydrographs, was used to estimate aquifer storage coefficient for nine study basins. The basin estimates range from 0.002 to 0.140; however, most estimates are within a narrow range of values, from 0.01 to 0.025. Accordingly, storage coefficient is estimated to be 0.01 for all aquifers in Middle and East Tennessee, with the exception of the aquifer in the inner part of the Central Basin, for which storage coefficient is estimated to be 0.002. Estimates of aquifer hydraulic diffusivity are derived from estimates of the streamflow recession index and drainage density for 75 drainage basins; values range from 3,300 to 130,000 ft^2/d (feet squared per day). Basin-specific and site-specific estimates of transmissivity are computed from estimates of hydraulic diffusivity and specific-capacity test data, respectively. Basin-specific, or areal, estimates of transmissivity range from 22 to 1,300 ft^2/d, with a mean of 240 ft^2/d In general, areal transmissivity is highest for basins underlain by the Cumberland Plateau aquifer (mean value 480 ft^2/d) and lowest for basins underlain by the Central Basin aquifer (mean value 79 ft^2/d). Mean transmissivity values for the Highland Rim, Valley and Ridge, and Blue Ridge aquifer are 320,140, and 120 ft^2/d respectively. Site-specific estimates of transmissivity, computed from specific-capacity data from 118 test wells in Middle and East Tennessee range from 2 to 93,000 ft^2/d with a mean of 2,600 ft^2/d Mean transmissivity values for the Cumberland Plateau, Highland Rim, Central Basin, Valley and Ridge, and Blue Ridge aquifers are 2,800,1,200, 7,800, 390, and 65Oft Id, respectively.

Tennessee

Application of a Geographic Information System for regridding a ground-water flow model of the Columbia Plateau Regional Aquifer System, Walla Walla River basin, Oregon-Washington

Computerized Geographic Information Systems (GIS) have become viable and valuable tools for managing,analyzing, creating, and displaying data for three-dimensional finite-difference ground-water flow models. Three GIS applications demonstrated in this study are: (1) regridding of data arrays from an existing large-area, low resolution ground-water model to a smaller, high resolution grid; (2) use of GIS techniques for assembly of data-input arrays for a ground-water model; and (3) use of GIS for rapid display of data for verification, for checking of ground-water model output, and for the cre.ation of customized maps for use in reports. The Walla Walla River Basin was selected as the location for the demonstration because (1) data from a low resolution ground-water model (Columbia Plateau Regional Aquifer System Analysis [RASA]) were available and (2) concern for long-term use of water resources for irrigation in the basin. The principal advantage of regridding is that it may provide the ability to more precisely calibrate a model, assuming chat a more detailed coverage of data is available, and to evaluate the numerical errors associated with a particular grid design.Regridding gave about an 8-fold increase in grid-node density.Several FORTRAN programs were developed to load the regridded ground-water data into a finite-difference modular model as model-compatible input files for use in a steady-state model run.To facilitate the checking and validating of the GIS regridding process, maps and tabular reports were produced for each of eight ground-water parameters by model layer. Also, an automated subroutine that was developed to view the model-calculated water levels in cross-section will aid in the synthesis and interpretation of model results.

Water-Resources Investigations Report

Water resources of the Palau Islands

The Palau Islands are a group of 350 islands, ranging in size from a few hundred square feet to the 153-square-mile island of Babelthuap. Babelthuap is the second largest island in the Western Pacific and comprises more than 80 percent of the total land area of the Palau Islands. Most of the islands are uninhabited limestone ridges covered with dense vegetation. These islands have no freshwater resources and are not included in this report. The island of Koror with an area of 3.6 square miles is the administrative, commercial, and population center of Palau and has an annual average rainfall of 148 inches. Short-term rainfall records at other locations in the islands indicate little variation in annual rainfall throughout the Palau Islands. Runoff-to-rainfall ratios for streams on Babelthuap show that about 70 percent of the rain falling on the island runs off to the ocean. The uniformity of rainfall and basin characteristics is shown by the excellent correlation between mean annual rainfall on Koror and streamflow on Babelthuap and by the close correlations between discharge at gaging stations and partial-record sites. Surface water quality is generally very good as shown by 55 chemical analyses of water from 18 sources. The dissolved solids concentration of water samples did not exceed 66 milligrams per liter. This report summarizes in one volume hydrologic data collection in a 14-year period of study and provides interpretations of the data than can be used by planners and public works officials as a basis for making decisions on the development and management of the islands' water resources.

Water-Resources Investigations Report

Potentiometric surface of the Ozark Aquifer in northern Arkansas, 1995

The Ozark aquifer in northern Arkansas is comprised of dolostones, limestones, sandstones, and shales of Late Cambrian to Middle Devonian age, and ranges in thickness from approximately 1,100 feet to more than 4,000 feet. Hydrologically, the aquifer is complex, characterized by discrete and diffuse flow components with large spatial variations in porosity and permeability. Regionally, the flow within the aquifer is to the south and southeast in the eastern and central part of the study area and to the northwest and north in the western part of the study area. Within Arkansas, the potentiometric-surface map based on October- December 1995 data indicates maximum water-level altitudes of greater than 1,300 feet in Boone, Carroll, and Madison Counties and minimum water-level altitudes of less than 400 feet in Independence, Izard, Lawrence, Randolph, Sharp, and Stone Counties. Comparing the 1995 potentiometric-surface map with a predevelopment potentiometric- surface map (Imes, 199), indicates general agreement between the two surfaces except in parts of Benton and Sharp Counties. Water-level differences could be attributed to differences in the time of year in which the water-level data were collected, differences in pumping conditions just prior to water-level measurement, differences in interpretation resulting (in part) from greater number of water-level measurements used for this report than for Imes (1990), or erroneous water-level data.

Water-Resources Investigations Report

Hydrogeologic data for the Quinnipiac River basin, Connecticut

This report contains geologic, ground-water, and quality-of-water data collected for the ground-water part of a water-resources inventory of the Quinnipiac River basin, Connecticut. The study was made by the U.S. Geological Survey in fiscal cooperation with the Connecticut Department of Environmental Protection. Collection sites for data used in the study are shown in plate A. A companion report interprets the ground-water, quality-of-water, and surfacewater data collected for the study (Connecticut Water Resources Bulletin No. 27, in parparation). The Quinnipiac River basin~ as used in this report~ is a 360-square-mile area in south-central Connecticut drained principally by the Quinnipiac River and its tributaries and several smaller streams~ which drain directly to Long Island Sound. (See front cover and plate A.) The study area includes all or parts of the following towns: Ansonia, Berlin, Bethany, Branford, Bristol, Cheshire, Derby, Durham, East Haven, Farmington, Guilford, Hamden, Meriden, Middlefield, Middletown, Milford, New Britain, New Haven, North Branford, North Haven, Orange, Plainville, Prospect, Southington, Wallingford, West Haven, Wolcott, and Woodbridge. Data collected for this investigation from July 1969 to December 1971 were supplemented by data collected during previous investigations. This report includes some records of wells and test holes published in Connecticut Water Resources Bulletin No. 5 and also includes some records used but not published in Connecticut Water Resources Bulletin No. 14. Table 5 contains old but previously unpublished analyses of water from wells in New Haven collected primarily from 1938 to 1949. Ownership of the sampled wells, as shown in table 1 and table 5, was determined at the time of the original inventory, and this information may now be outdated. Many of these wells have been destroyed since they were last sampled and others, though still in existence, are no longer in use.

Connecticut

Methodology used to produce an encoded 1:100,000-scale digital hydrographic data layer for the Pacific Northwest

The U.S. Geological Survey (USGS) has produced a River Reach File data layer for the Pacific Northwest for use in water-resource management applications. The Pacific Northwest (PNW) River Reach Files, a geo-referenced river reach data layer at 1:100,000-scale, are encoded with the U.S. Environmental Protection Agency"s (EPA) reach numbers. The encoding was a primary task of the River Reach project, because EPA"s reach identifiers are also an integral hydrologic component in a regional Northwest Environmental Data Base-an ongoing effort by Federal and State agencies to compile information on reach-specific resources on rivers in Oregon, Idaho, Washington, and western Montana. A unique conflation algorithm was developed by the USGS to transfer the EPA reach codes and other meaningful attributes from the 1:250,000-scale EPA TRACE graphic files to the PNW Reach Files. The PNW Reach Files also were designed so that reach-specific information upstream or downstream from a point in the stream network could be extracted from feature attribute tables or from a Geographic Information System. This report documents the methodology used to create this 1:100,000-scale hydrologic data layer.

Water-Resources Investigations Report

Water-quality characteristics and trends for selected sites in or near the Earth Resources Observation Systems (EROS) Data Center, South Dakota, 1973-2000

This report presents data on water-quality samples that were collected in and near the Earth Resources Observation Systems (EROS) Data Center from 1973 through 2000. The investigation is a collaborated effort between the U.S. Geological Survey, Water Resources Discipline (WRD), and Geography (formerly National Mapping) Discipline, EROS Data Center. A water-quality monitoring program was initiated in 1973, when the EROS Data Center was constructed, and continues at the present time (2003). Under this program, water-quality samples were collected at various sites on the EROS Data Center's property and in the surrounding area. These sites include 4 wastewater-treatment lagoons, 1 site on EROS Lake located behind the EROS Data Center, 2 stream sites near the EROS Data Center, and 9 ground-water wells surrounding the EROS Data Center. Additionally, 3 sites on EROS Lake, 7 stream sites, and 9 ground-water sites are located within the study area and have been sampled during the period covered in the report. Some of these additional sites were part of the initial water-quality monitoring conducted during and immediately after the construction of the EROS Data Center. For other sites, some special sampling (depth-profile and bottom material) has occurred at times during the sampling history; however, these sites have little water-quality data and were not used for statistical or trend analysis. A trend-analysis program, Estimate TREND (ESTREND), was used to analyze for trends for one surface-water site, the Big Sioux River, which was the only site that had a substantial number of samples collected during an extensive period. The ESTREND trend-analysis program was used to analyze 16 constituents. Specific conductance and dissolved orthophosphate were the only constituents determined to have statistically significant trends. Results showed an increasing trend for specific conductance and a decreasing trend for dissolved orthophosphate. Scatter plots with regression smoothing lines for selected constituents are presented for selected surface-water and ground-water sites. Regression analyses using a Lowess (Locally Weighted Scatterplot Smoothing) smoothing line for Split Rock Creek, EROS Lake, the lagoon sites, and the ground-water sites indicated variable results, with some constituents indicating an increasing or decreasing trend, some having varied results, and others indicating no change during the sampling period.

South Dakota

Areas of gain and loss along the Platte River, central Nebraska, spring 1999

In an effort to protect endangered and other wildlife species, the governors of Nebraska, Colorado, and Wyoming, and the Secretary of the U.S. Department of the Interior signed an agreement in 1997 (Platte River Endangered Species Partnership, 1997) to initiate the development of a basin-wide habitat recovery program for the central reaches of the Platte River in Nebraska. This agreement recognizes the need to maintain minimal flows in the central reaches of the Platte River. An understanding of the surface-water and ground-water interaction along the central reaches of the Platte River is critical to deliver water to the targeted habitat areas. Therefore, a study by the U.S. Geological Survey (USGS), in cooperation with the Bureau of Reclamation and the U.S. Fish and Wildlife Service, was conducted to determine qualitatively the areas of gain and loss along the central Platte River between Gothenburg and Silver Creek, Nebraska (fig. 1). The purpose of this report is to present the results of the study.

Nebraska

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory-Determination of organophosphate pesticides in bottom sediment by gas chromatography with flame photometric detection

A method for the isolation of 20 parent organophosphate pesticides and 5 pesticide degradates from bottom-sediment samples is described. The compound O-ethyl-O-methyl-S-proplyphosphorothioate is reported as an estimated concentration because of variable performance. In this method, the sediment samples are centrifuged to remove excess waster mixed with anhydrous sodium sulfate and Soxhlet extracted overnight with dichloromethane (93 percent) and methanol (7 percent). The extract is concentrated and then filtered through a 0.2-micrometer polytetrafluoroethylene membrane syringe filter. An aliquot of the sample extract is quantitatively injected onto two polystyrene-divinylbenzene gel-permeation chromatographic columns connected in series. The compounds are eluted with dichloromethane and a fraction is collected for analysis, with some coextracted interferences, including elemental sulfur, separated and discarded. The aliquot is concentrated and solvent exchanged to ethyl acetate. The extract is analyzed by dual capillary-column gas chromatography with flame photometric detection. Single-operator method detection limits in sodium sulfate matrix samples ranged from 0.81 to 2 micrograms per kilogram. Method performance was validated by spiking all compounds into three different solid matrices (sodium sulfate, bed sediment from Clear Creek, and bed sediment from Evergreen Lake) at three different concentrations. Eight replicates were analyzed at each concentration in each matrix. Mean recoveries of method compounds spiked in Clear Creek samples ranged from 43 to 110 percent, and those in Evergreen Lake samples ranged from 62 to 118 percent for all pesticides. Mean recoveries of method compounds spiked in reagent sodium sulfate samples ranged from 41 to 101 percent for all pesticides. The only exception was O-ethyl-O-methyl-S-propylphosphorothioate, which had an average recovery of 35 percent, and, thus, sample concentration is reported as estimated ('E' remark code).

Water-Resources Investigations Report

Monthly and annual water budgets of Lake Wingra, Madison, Wisconsin, 1972-77

This report presents estimated annual and monthly water budgets for Lake Wingra and the adjacent wetland area for January 1972 through September 1972. Annually, inputs from precipitation, surface runoff, and groundwater inflow are approximately equal (31, 34, and 35 percent, respectively). Outputs include outflow from the lake into Murphy Creek (70 percent), evapotranspiration from the lake and wetland (26 percent), and ground-water outflow (4 percent). The inputs and outputs vary seasonally. In months when snowmelt occurs, surface runoff is a major input (56 percent in March; 46 percent in April). In fall and winter ground-water inflow is a major input (57 percent in November). Precipitation comprises 41 percent of the input in August but only 18 percent in January. Lake outflow is the major output except from July through September. Combined evaporation and evapotranspiration is a major output in summer (45 to 58 percent) but minor in winter (less than 13 percent). Ground-water outflow is a small part of the budget each month, ranging from 2 percent in March and April to a maximum of 7 percent in September. The water budget is based on field data collected from January 1972 through June 1973, and on fragmentary data and estimates for July 1973 through September 1977. The budget terms differ from those published by Oakes, Hendrickson, and Zuehls (1975, table 10) because springflow has been included in total ground-water inflow and estimated on a monthly basis in this report. Previously only annual estimates were provided.

Wisconsin

Bias and precision of selected analytes reported by the National Atmospheric Deposition Program and National Trends Network, 1984

The U.S. Geological Survey operated a blind audit sample program during 1974 to test the effects of the sample handling and shipping procedures used by the National Atmospheric Deposition Program and National Trends Network on the quality of wet deposition data produced by the combined networks. Blind audit samples, which were dilutions of standard reference water samples, were submitted by network site operators to the central analytical laboratory disguised as actual wet deposition samples. Results from the analyses of blind audit samples were used to calculate estimates of analyte bias associated with all network wet deposition samples analyzed in 1984 and to estimate analyte precision. Concentration differences between double blind samples that were submitted to the central analytical laboratory and separate analyses of aliquots of those blind audit samples that had not undergone network sample handling and shipping were used to calculate analyte masses that apparently were added to each blind audit sample by routine network handling and shipping procedures. These calculated masses indicated statistically significant biases for magnesium, sodium , potassium, chloride, and sulfate. Median calculated masses were 41.4 micrograms (ug) for calcium, 14.9 ug for magnesium, 23.3 ug for sodium, 0.7 ug for potassium, 16.5 ug for chloride and 55.3 ug for sulfate. Analyte precision was estimated using two different sets of replicate measures performed by the central analytical laboratory. Estimated standard deviations were similar to those previously reported. (Author 's abstract)

Water-Resources Investigations Report

The use of three-parameter rating table lookup programs, RDRAT and PARM3, in hydraulic flow models

Subroutines RDRAT and PARM3 enable computer programs such as the BRANCH open-channel unsteady-flow model to route flows through or over combinations of critical-flow sections, culverts, bridges, road- overflow sections, fixed spillways, and(or) dams. The subroutines also obstruct upstream flow to simulate operation of flapper-type tide gates. A multiplier can be applied by date and time to simulate varying numbers of tide gates being open or alternative construction scenarios for multiple culverts. The subroutines use three-parameter (headwater, tailwater, and discharge) rating table lookup methods. These tables may be manually prepared using other programs that do step-backwater computations or compute flow through bridges and culverts or over dams. The subroutine, therefore, precludes the necessity of incorporating considerable hydraulic computational code into the client program, and provides complete flexibility for users of the model for routing flow through almost any affixed structure or combination of structures. The subroutines are written in Fortran 77 language, and have minimal exchange of information with the BRANCH model or other possible client programs. The report documents the interpolation methodology, data input requirements, and software.

Water-Resources Investigations Report

Water resources of Soledad, Poway, and Moosa basins, San Diego County, California

Reclaimed water is being considered as as supplemental water supply in the Soledad, Poway, and Moosa basins, San Diego County. This report describes the geology, soils, hydrology, and cultural factors in each of the basins as they relate to use of reclaimed water. Imported water is currently the major water-supply source in the basins. Groundwater supplies are used to a limited extent for both agricultural and domestic needs. Surface water flows are intermittent and, therefore, have not been developed for use in the basins. All three of the basins have the potential for use of reclaimed water, but only the Moosa basin is currently implementing a plan for such use. Concentrations of dissolved solids, chloride, and sulfate in both ground and surface water commonly exceed local basin objectives. As of 1985, plans for use of reclaimed water are oriented toward improving the quality of the groundwater.

California

Water-quality and algal conditions in the North Umpqua River Basin, Oregon, 1992-95, and implications for resource management

This report describes the results of a synoptic water-quality and algal investigation during July 1995 at 36 stream sites in a 1,350 square-mile area of the North Umpqua River Basin, Oregon. The study area includes a headwaters hydroelectric project area, a Wild and Scenic reach in the main stem immediately downstream, and the watersheds of several major tributaries. Additional data from previous investigations are reviewed, and impacts on water quality in the Wild and Scenic reach from resource management, including forestry and reservoir operations, are inferred where sufficient data exist. Water-quality standards were occasionally exceeded for dissolved oxygen and pH, and daily maximum stream temperatures in the Wild and Scenic reach were higher than both the 1996 standard for the State of Oregon and the optimal temperature ranges for many anadromous fish. Dissolved oxygen in the basin was controlled more by stream temperature and reaeration than by primary production. Arsenic concentrations in the river during low flow (1 µg/L [microgram per liter]) indicate a potential cancer risk of between 1:5,000 and 1:20,000 for people using the river as a source of drinking water and fish for consumption. Streambed-sediment concentrations of arsenic, chromium, copper, manganese, and nickel were approximately double the sediment-quality criteria values adopted by New York State and by the Ontario Ministry of the Environment. High concentrations of phosphorus in bed sediments indicated that much of the phosphorus observed in the water column throughout the basin (medians: 32, 9, and 50 µg/L in the main stem, tributaries, and hydroelectric project areas, respectively) could have been geologically derived. Inorganic and organic nitrogen concentrations in water were mostly below minimum reporting limits (5 and 200 µg/L, respectively), indicating severe nitrogen limitation at most locations. Benthic algal biomass, biovolume, and chlorophyll a concentrations were highest at the sites directly below impoundments and at one headwater tributary (medians: 46 grams per square meter, 821 million cubic micrometers per square centimeter, and 126 milligrams per square meter, respectively), and were also somewhat elevated downstream in the Wild and Scenic reach compared with those in similar streams in the Pacific Northwest. Classification of the algal taxa indicated that, among all sites sampled, alkaliphilic taxa, nitrogen fixing taxa, and eutrophic taxa were the most abundant on the basis of biovolume and density. Cold-water taxa, facultative nitrogen heterotrophs, and oligotrophic taxa constituted the remainder of the taxa. Multivariate analyses indicated that algal communities at the hydroelectric-project-affected sites were distinct from communities at sites on the main stem and Steamboat Creek. At many locations, the river’s algal community might be compensating for the low nitrogen concentrations by fixation of atmospheric nitrogen or through heterotrophic assimilation of organic nitrogen. Water quality in the Wild and Scenic reach is dominated by water released from the hydroelectric project area during summer. Effects of the hydroelectric project include seasonal control of streamflow, water temperature, and phosphorus concentrations, and the possible release of low but ecologically important concentrations of organic nitrogen. A review of available data and literature suggests that the reservoirs can increase the interception of sediments and large organic debris, and promote their conversion into fine-grained particulate and dissolved organic matter for downstream transport. These effects could be compounded by the effects of forestry in the basin, including alteration of hydrologic cycles, changes in sediment and nutrient runoff, reductions of the transport of large woody debris, and degradation of habitat quality. It is hypothesized that, in the North Umpqua River, these processes have induced a fundamental shift in the river’s food web, from a detritus-based system to a system with a 2 higher emphasis on algal production. Confirmation of these changes and their effects on higher trophic levels are needed to properly manage the aquatic resources for all designated beneficial uses in the basin.

Oregon