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K.J. Covay

Publications and source records attributed to K.J. Covay.

7 recordsLinked to original sources
USGS2003

Morphometric and histopathological parameters of gonadal development in adult common carp from contaminated and reference sites in Lake Mead, Nevada

This study examined the hypothesis that exposure to sublethal concentrations of contaminants alters the gonadal condition of feral common carp Cyprinus carpio . Adult common carp in Lake Mead, Nevada, were collected from a contaminated site (Las Vegas Bay) that receives municipal and industrial effluent and from a reference site (Overton Arm) with a relatively low level of contamination. Fish were sampled seven times over a 1-year period extending over two separate spawning seasons. Morphometric and histopathological parameters of gonadal and germ cell development were determined. In males, the pattern of seasonal changes in the gonadosomatic index (GSI) was similar between the sites and showed no clear association with site-specific seasonal temperature profiles. However, Las Vegas Bay males had consistently lower GSI values and, on one of the sampling dates, a lower proportion of sperm relative to other germ cell stages (determined histologically). Further, Las Vegas Bay males had a higher incidence of gonadal macrophage aggregates, which are putative tissue biomarkers of contaminant exposure in fishes. In females, seasonal GSI profiles, the frequency of fish with postovulatory follicles (an index of spawning activity), and the timing of new follicle recruitment all showed differences between sites, but these differences generally matched differences in water temperature profile. Also, the peak size-frequency of full-grown follicles did not differ between sites, and estimates of fecundity for the second spawning season indicated that females from the reference site unexpectedly produced a lower number of gametes. Overall, site differences in gonadal condition were observed in carp of both sexes but they seemed to be associated with site differences in contaminant levels only in males. The apparent lack of association between contaminant level and gonadal condition in female carp from mildly mesotrophic Lake Mead may indicate a lack of contaminant effects in females or a confounding effect of the higher nutrient loads in the Las Vegas Bay environment.

Nevada↗
USGS2001

Sediment-deposition rates and organic compounds in bottom sediment at four sites in Lake Mead, Nevada, May 1998

In May 1998 the U.S. Geological Survey, in cooperation with the University of Nevada, Las Vegas, investigated rates of sediment deposition and concentrations of selected synthetic organic compounds at four sites in Lake Mead. Sediment cores were extracted from two sites (one shallow and one deep) in Las Vegas Bay, from one site in the Overton Arm, and from one site near the historic confluence of the Colorado and Virgin Rivers. The sediment cores were age-dated using cesium-137 and were analyzed for the presence of organochlorine compounds (pesticides and degradation products, polychlorinated biphenyls, dioxins, and furans) and for semivolatile organic compounds (polycyclic aromatic hydrocarbons and phenols). Sediment-deposition rates after impoundment of the Colorado River by Hoover Dam were determined by measuring the accumulation of mass during three different periods: (1) from the approximate impoundment date for each site (1935-37) to the initial occurrence of cesium-137 in the atmosphere (1952); (2) from 1952 to the maximum concentration of cesium-137 in the atmosphere (1964); and (3) from 1964 to the collection date of the sample (1998). Sediment-deposition rates for the entire post-impoundment period (1935-98) averaged 1.45 (g/cm2)/yr (grams per square centimeter per year) at the Las Vegas Bay shallow site, 1.25 (g/cm2)/yr at the Las Vegas Bay deep site, 0.80 (g/cm2)/yr at the Overton Arm site, and 0.65 (g/cm2)/yr at the Colorado and Virgin Rivers confluence site. Sediment-deposition rates after impoundment of the Colorado River by Hoover Dam were determined by measuring the accumulation of mass during three different periods: (1) from the approximate impoundment date for each site (1935-37) to the initial occurrence of cesium-137 in the atmosphere (1952); (2) from 1952 to the maximum concentration of cesium-137 in the atmosphere (1964); and (3) from 1964 to the collection date of the sample (1998). Sediment-deposition rates for the entire post-impoundment period (1935-98) averaged 1.45 (g/cm2)/yr (grams per square centimeter per year) at the Las Vegas Bay shallow site, 1.25 (g/cm2)/yr at the Las Vegas Bay deep site, 0.80 (g/cm2)/yr at the Overton Arm site, and 0.65 (g/cm2)/yr at the Colorado and Virgin Rivers confluence site. Total numbers of synthetic organic compounds detected in sediment samples were 48 at the Las Vegas Bay shallow site, 57 at the Las Vegas Bay deep site, 26 at the Overton Arm site, and 31 at the Colorado and Virgin Rivers confluence site. The most commonly detected organochlorine pesticide and polychlorinated biphenyl compounds were dichlorodiphenyldichloroethane and dichlorodiphenyldichloroethylene. The most commonly detected dioxin compounds were tetrachlorodibenzo-p-dioxin and octochlorodibenzo-p-dioxin. The most commonly detected furan compounds were tetrachlorodibenzofuran and octochlorodibenzofuran. The most commonly detected polycyclic aromatic hydrocarbons included perylene, benzo[g,h,i]perylene, 2,6-dimethylnaphthalene, and indeno[1,2,3-c,d]pyrene. The most commonly detected phenol compound was phenol.

Open-File Report↗
USGS1985

Benthic invertebrates in selected streams of the Piceance Creek basin, northwestern Colorado, water years 1977-81

Data from the periodic collection of benthic invertebrates at six streamflow stations in the basin during water years 1977-81 are presented and summarized. A total of 162 genera from 8 insect orders and 8 non-insect orders were documented. Numbers of organisms per sample ranged from 0 to 3,700. Counts generally were greater during low streamflow. Diptera (two-winged flies) were the most numerous organisms and the percent composition of Diptera increased downstream. Organisms associated with both unpolluted and polluted streams were collected. The assignment of taxa into trophic groups placed most taxa into the burrowers-sprawlers-clingers (habits) groups and primary and secondary consumer (food-web) groups. General community structure, however, remained balanced and stable. Mean diversity indices ranged from 2.21 to 2.82 and similarity indices indicate better than 50% consistency of composition. Mean diversity indices were greatest in the middle part of the Piceance Creek basin. The distribution of benthic invertebrates collected indicated that no deleterious water quality conditions existed during the study period. Differences in benthos communities within and between sites are attributed to differences in water discharge, water temperature, substrate, and chemical quality of water. (USGS)

Water-Resources Investigations Report↗
USGS1985

Water-quality characteristics of streams in the Piceance Creek and Yellow Creek drainage basins, northwestern Colorado, water years 1977-81

Physical and chemical data for streams in the Piceance Creek and Yellow Creek drainage basins, Colorado collected during the 1977-81 water years are summarized. Stream temperatures ranged from -0.5 to 35.0 degrees Celsius and were warmest near the downstream reaches of Piceance and Yellow Creeks. Minimum concentrations of dissolved oxygen were greater than 3.0 milligrams per liter in Piceance and Yellow Creeks, and concentrations of dissolved oxygen exceeded saturation during periods of active photosynthesis. Values of pH in streams ranged from 6.9 to 9.0 and were least during snowmelt runoff and greatest in low flows in the lower reaches of Piceance and Yellow Creeks. Concentrations of suspended sediment exceeded 100 ,000 milligrams per liter in localized runoff. Specific conductance varied inversely with discharge. Sodium, magnesium, bicarbonate, and sulfate ions and concentration ranges of dissolved solids between 400 and 1,700 milligrams per liter were characteristic of the water quality of the perennial streams. Calcium and bicarbonate dominated the major ions, and concentrations of dissolved solids normally were less than 600 milligrams per liter in the intermittent streams during storm and snowmelt runoff. Augmentation to Piceance and Yellow Creeks from ground-water sources in the lower reaches of both streams increased concentrations of dissolved solids several thousand milligrams per liter during medium and low flows and caused a change in water-quality type from sodium magnesium bicarbonate to a high-percentage sodium bicarbonate. Increases in dissolved concentrations of arsenic, boron, fluoride, lithium, strontium, and sulfate were related to ground-water sources or discharges from areas of energy resource development. (USGS)

Water-Resources Investigations Report↗
USGS1984

Quantity and quality of streamflow in the White River basin, Colorado and Utah

The water quality and flow of existing streams in the White River basin, located in northwestern Colorado and northeastern Utah, are adequate for present uses, but future development (such as energy) may affect stream quality and quantity. Present conditions are described as a baseline to enable planners to allocate available water and to measure changes in quantity and quality of water in the future. The White River basin contains extensive energy resources consisting of oil, natural gas, coal, and oil shale. Large quantities of water will be required for energy-resource development and associated municipal and industrial uses. An average of 70% of the annual flow in the White River occurs during May, June, and July as a result of snowmelt runoff. The 7-day, 10-year low-flow discharges/sq mi and the 1-day, 25-year high-flow discharges/sq mi are larger in the eastern part of the basin than in the western part. Flow-duration curves indicate that high flows in the White River and the North and South Fork White Rivers result mainly from snowmelt runoff and that base flow is sustained throughout the year by groundwater discharge from the alluvial and bedrock aquifers. Water type varies in the basin; however, calcium and sodium are the dominantly occurring cations and sulfate and bicarbonate are the dominantly occurring anions. Computed total annual dissolved-solids loads in the White River range from 31 ,800 tons/yr in the North Fork White River to 284,000 tons/yr at the mouth. A 10% increase to a 14% decrease of the dissolved-solids load could result at the mouth of the White River near Ouray, Utah. This corresponds to a 5% increase to a 10% decrease in dissolved-solids concentration. The seasonal pattern of stream temperatures was found to fit a harmonic curve.

Colorado, Utah↗