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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 55 records · Page 3Linked to original sources
USGS1977

Geology and water-supply potential of the Anoka Sand Plain aquifer, Minnesota

Intensified land development on the Anoka sand plain necessitates a better understanding of the hydrogeology of the surficial outwash deposits of the area. The Anoka sand-plain aquifer consists of outwash attributable to two different ice lobes. Predominant grain size of the upper outwash decreases and sorting coefficient increases from west to east. Till or lake deposits underlie most of the surficial outwash. In some areas, these deposits are absent and the aquifer is directly underlain by bedrock, mainly sandstone. Preliminary study indicates that parts of the aquifer may yield several hundred to more than 1,000 gallons of water per minute to properly developed large-diameter wells. Storage in the aquifer is estimated to be 2,000 billion gallons and annual withdrawals approaching 250 billion gallons may be sustained. More detailed analysis is essential for proper management and optimum use of the resource.

Minnesota↗
USGS1980

Laboratory procedure for estimating residue dynamics of xenobiotic contaminants in a freshwater food chain

A laboratory method of measuring the accumulation, transfer, elimination, and degradation of xenobiotic contaminants is described for organisms in a freshwater food chain (microorganisms, filter-feeder, and fish). A flow-through diluter-system, 14 C-labeled contaminants, gas and thin-layer chromatography, autoradiography, and liquid scintillation spectrometry are used in making residue determinations. Accumulation factors and various index values are developed for measuring and estimating potential accumulation of xenobiotic contaminants by aquatic organisms. The laboratory procedure is economical, simple, reproducible, and ecologically relevant.

Technical Paper↗
USGS1983

Biology, population structure, and estimated forage requirements of lake trout in Lake Michigan

Data collected during successive years (1971-79) of sampling lake trout ( Salvelinus namaycush ) in Lake Michigan were used to develop statistics on lake trout growth, maturity, and mortality, and to quantify seasonal lake trout food and food availability. These statistics were then combined with data on lake trout year-class strengths and age-specific food conversion efficiencies to compute production and forage fish consumption by lake trout in Lake Michigan during the 1979 growing season (i.e., 15 May-1 December). An estimated standing stock of 1,486 metric tons (t) at the beginning of the growing season produced an estimated 1,129 t of fish flesh during the period. The lake trout consumed an estimated 3,037 t of forage fish, to which alewives ( Alosa pseudoharengus ) contributed about 71%, rainbow smelt ( Osmerus mordax ) 18%, and slimy sculpins ( Cottus cognatus ) 11%. Seasonal changes in bathymetric distributions of lake trout with respect to those of forage fish of a suitable size for prey were major determinants of the size and species compositions of fish in the seasonal diet of lake trout.

Technical Paper↗