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A Proposal To Fertilize The Overton Arm And Gregg Basin Areas Of Lake Mead, Larry J. Paulson

Publications (WR)

Several limnological studies have been conducted in Lake Mead during the past decade. The recent studies clearly show that most of Lake Mead is deficient in nutrients, especially phosphorus, and very low in productivity. The reservoir-wide average total phosphorus concentration for 1981 - 1982 was only 9 mg/m³. This is below levels found In most oligotrophic lakes and reservoirs. Algal biomass, as measured by chlorophyll-a, averaged only 1.5 mg/m³. That also places Lake Mead in the oligotrophic range. Transparency, as measured by a Secchi disc, averaged 9-5 m in Lake Mead during 1981-1982. That far exceeds …

Glaciochemical Investigations As A Tool In The Historical Delineation Of The Acid Precipitation Problem, William B. Lyons, Paul Andrew Mayewski

Earth Science Faculty Scholarship

Precipitation in the Northern Hemisphere has been recently recognized to have hydrogen ion concentrations 10 to 100 times higher than expected for natural precipitation (Likens and Bormann 1974, Cogbill and Likens 1974, Lewis and Grant 1980). However, controversy has arisen regarding the nature of the acidity of the precipitation sampled and whether, indeed, the pH of North American precipitation has increased over time (Miller and Everett 1979, Lerman 1979, Stensland 1980, Sequeria 1981, Carlson and Rodhe 1982). In most locations pH records have been constructed rather imperfectly due to differences in sampling, handling, and analytical procedures used (Galloway and Likens …

Seasonal And Spatial Heterogeneity In The Limnetic Zooplankton Community Of Lake Mead, Gene Robert Wilde

Publications (WR)

Zooplankton samples collected from throughout Lake Mead, in 1981-1982, demonstrate the presence of a statistically significant seasonal and spatial heterogeneity in zooplankton densities. Seasonally, the major zooplankton groups were most abundant in the spring and fall, coincident with maxima in chlorophyll-a concentrations. Successions among the various rotifers, cladocerans and copepods present in the reservoir were influenced by food availability, diapause, predation by planktivorous fish and, possibly, water temperatures.

Spatial heterogeneity in zooplankton densities was unrelated to water temperature, pH, conductivity and dissolved oxygen concentrations, but was related to the abundance of phytoplankton (chlorophyll-a concentrations) and fish. Statistical analyses indicate that …

The Role Of Nannoplankton In The Phytoplankton Dynamics Of Four Colorado River Reservoirs (Lakes Powell, Mead, Mohave, And Havasu), Jeffrey John Janik

Publications (WR)

Phytoplankton species composition and community size structure were studied in four warm-monomictic Colorado River reservoirs; lakes Powell, Mead, Mohave, and Havasu from March 1981 to February 1982. Sampling was done at approximately monthly intervals from several stations in each reservoir. The Utermohl technique was used to enumerate phytoplankton. The phytoplankton assemblage was divided into the following six size classes using microscopic techniques; netplankton (>64 um), and nannoplankton (>5, 5-11, 12-21, 22-44, and 45-64 um).

Total phytoplankton biomass and community size structure were different among these four reservoirs with considerable spatial and temporal variation present. Average reservoir-wide areal weighted …

Las Vegas Wash Multispectral Scanner Survey, T. H. Mace, M. V. Olsen, Environmental Protection Agency

Publications (WR)

At the request of the U.S. Bureau of Reclamation, Boulder City, Nevada, the U.S. Environmental Protection Agency's Environmental Monitoring Systems Laboratory at Las Vegas collected multispectral scanner imagery of Las Vegas Wash on October 1, 1982.

A combined maximum likelihood classification and editing procedure was used to classify the multispectral scanner imagery into 12 categories of land cover. The classification identified four categories of marsh vegetation, one category of riparian, two categories of mixed scrub, and two desert categories. Turbid water and cultivated land formed an "other" category. Area tabulations were formed by georeferencing the classification to the Universal Transverse …

Monthly Report On The State Of Rivers 1984, Albert Kuo

Reports

Chiefly graphs showing monthly salinity, temperature, dissolved oxygen distributions at slackwater for the James, York, Pamunkey, and Rappahannock Rivers.

1984: April, May, June, July, August, September, October

Factors Affecting Reproductive Success Of Bonytail Chubs And Razorback Suckers In Lake Mohave, Michael A. Bozek, Larry J. Paulson, James E. Deacon, U.S. Department Of Interior, Fish And Wildlife Service

Publications (WR)

Razorback suckers (Xyrauchen texanus) and bonytail chubs (Gila elegans) were once widespread throughout the Colorado River system. The ranges and populations of these native species and others have declined in the past 50 years. Bonytail chubs appear to be extremely rare and possibly nearing extinction in the Upper Colorado River Basin. The razorback sucker is widely distributed in the upper river but is considered rare throughout most of that range and is also rare in the Grand Canyon. Razorback suckers are abundant only in a few habitats in the upper river. They congregate and spawn over …

Las Vegas Wash Advanced Water Quality Study: Final Report, Richard A. Roline, James J. Sartoris, U.S. Bureau Of Reclamation

Publications (WR)

The purpose of the Las Vegas Wash Advanced Water Quality Study is to determine the existence, extent, and mechanisms of nutrient and toxin stripping in Las Vegas Wash under present conditions and under future conditions, both with and without construction of the proposed salinity control unit as described by the Bureau of Reclamation (USBR, 1982b). This study was performed for the Lower Colorado Region Division of Planning by personnel of the Environmental Sciences Section of the Division of Research and Laboratory Services, E&R Center, Denver, Colorado. Work on the study began in February 1983.

The general approach adopted for this …

Investigations And Research In Nevada By The Water Resources Division, U. S. Geological Survey, 1982-83, Terry Katzer, Otto Moosburner, William D. Nichols

Publications (WR)

The Water Resources Division, U.S. Geological Survey, is charged with (1) maintaining a hydrologic network in Nevada that provides information on the status of the State's water resources and (2) engaging in technical water-resources investigations that have a high degree of transferability. To meet these broad objections, 26 projects were active in Nevada during fiscal year 1982 in cooperation with 36 Federal, State, and local agencies. Total funds were $3,319,455, of which State and local cooperative funding amounted to $741,500 and Federal funding (comprised of Geological Survey Federal and cooperative programs plus funds from six other Federal agencies) amounted to …

Kepone Uptake: A Comparison Of Field And Laboratory Data, Micheal E. Bender, Robert J. Huggett, Harold D. Sloane

VIMS Books and Book Chapters

The ability to predict the environmental fate and effects of pollutants in the marine environmenits of utmost importance in assessing the hazards posed by a compound's use and/or disposal. Most commonly utilized methods to establish potential environmental effects have involved an assessment with bioassays of a compound's acute and chronic toxicity. For compounds that have the ability to bioaccumulate, the potential dangers from this process must also be determined. A "first cut" estimate can be made by determining the partition coefficients between an organic solvent, usually n-octanol, and water. If this coefficient exceeds 25,000, EPA requires a report of the …

A Study Of Long-Term Environmental Fluctuations In The Chesapeake Bay Region, Reidar S. Leinebo, David A. Evans

Reports

A time series of monthly mean values of temperature measurements (1952-1981) for Gloucester Point, Virginia, U.S.A. and Vardo In Northern Norway are described and the results of an eigenfunction analysis are presented. Seasonal, year-to-year and long term changes of salinlty measurements (1960-1977) for Gloucester Point and monthly mean stream-flow values (1951-1982) are also described. Commerclal Catch data from Virginia for menhaden, bluefish and Atlantic croaker shows reasonable correlation with cllmatlc changes.

The time around 1965 was a cold period with high sallnlty and low streamflow. The same period was also cold In Northern Norway (Europe). Around 1974 was a period …