The following report is the fourth in a series of reports on rare and uncommon elements prepared by the Geological Survey. This report covers columbius and tantalus, two chemical elements belonging to the fifth group of the periodic table and quinquevalent in most of their compounds.

Abstract: Procedures are presented in detail of two methods for the determination of very small percentages or uranium (down to 0.0025). The methods are applicable to a wide variety of materials. Notes on the methods and confirmatory experiments are also given.

From abstract: This report examines and compares "the quality of water discharging from a strip-mined basin and a relatively unmined basin on the Cumberland Plateau in Tennessee." They determine that "the chemical and aesthetic quality of these waters will directly affect the chemical and aesthetic quality of the water flowing through a proposed national river and recreation area." It includes maps, graphs, and tables.

From abstract: A preliminary quasi-three-dimensional finite-difference ground-water-flow model of the seven-county Twin Cities Metropolitan area was constructed and used to evaluate parameter sensitivity and adequacy of available data.

From abstract: This report evaluates "four dam-break flood-wave models [...] by using three field data sets and selected criteria of desirable features." It includes maps, graphs, and tables.

The model discussed in this report simulates recharge to, flow through, and discharge from the water-table aquifer representative of most of Chester County, Pennsylvania. It includes maps and graphs.

This report evaluates and describes the effects that strip mining the Anna S. Mine has on the water quality of Babb Creek in Pennsylvania. It includes maps, graphs, and tables.

This report presents a historical review of sediment-data collected for the San Francisco Bay systems in California from 1909 to 1966. It includes maps, graphs, tables, and a foreword.

From introduction: This report contains a general description of the hydrology of the project site, summaries of the data collected during 1971 to 1978, and discusses some of the factors affecting the hydrology of the site. This information and the water-level contour map (Fuentes and Patterson, 1979) will be helpful in designing an effective ground-water monitoring program and will provide baseline hydrologic information from which future changes can be detected.

From purpose and scope: The purpose of this study was to update hydrologic data and refine understanding of the hydrologic system within the San Dieguito, San Elijo, and San Pasqual hydrologic subareas in San Diego County, Calif., and to evaluate the suitability of these areas for reclaimed water use.

From abstract: This report provides "hydrologic information for the north-central and western coal-mining regions of Missouri . . . to define the hydrologic system in these areas of major historic and planned coal development." It "describes the physical setting, climate, coal-mining practices, general hydrologic systems, and the current (1980) hydrologic data base in these two coal-mining regions."

Abstract: The primary effect of a floodwater-retarding structure (FRS) on the flow of Trout Creek, Wisconsin, is attenuation of flood peaks. Reduction of flood peaks ranged from 58 to 91 percent during the study period, 1975 to 1979. An inverse relationship exists between sediment concentration and outflow from the FRS during floods. Most sediment stored in the flood pool during floods is released from the reservoir during subsequent reduced discharge. Sediment-trapping efficiency of the FRS was 7 percent during the 4-year study. The bankfull capacity of the channel was reduced from 154 cubic feet per second upstream from the FRS to 65 cubic feet per second downstream. Mean bankfull depth downstream from the FRS has adjusted to a value 45 percent less than upstream from the structure due to the sedimentation of materials transported from the FRS during reduced flows. The FRS was not found to have any significant adverse effect on the arthropod fauna or trout reproduction in Trout Creek from 1975 to 1979. During 1960-1979, winter floods seem to have had the greatest adverse effect on the survival of brown trout eggs and sac fry.

From introduction: The purpose of this report is to describe the general quality and quantity of water in the principal water-supply aquifers in Minnesota.

This report analyses resistivity and porosity logs to determine water-quality trends in carbonate aquifers. It contains tables and other figures.

This report uses data collected from seventeen lakes and ponds in Eagan, Minnesota from 1972 through 1978 to determine the effects of urbanization on water quality. It contains a map, graphs, and tables.