Geology topics

N.D. Jacobson

Publications and source records attributed to N.D. Jacobson.

2 recordsLinked to original sources

USGS1984

Hydrogeology of eastern Michaud Flats, Fort Hall Indian Reservation, Idaho

Groundwater in Michaud Flats, southeastern Idaho, is developed extensively for irrigation and industry. Extensive clay beds overlie the Bighole Basalt and Sunbeam Formation, which yield most of the water for irrigation and industrial wells; artesian aquifers in these rock units have heads below land surface and near those in the shallow water-table aquifer in the overlying Michaud Gravel. Transmissivities in artesian aquifers range from 19,6000 to 444,000 feet squared per day. High levels of arsenic were detected in groundwater in the Flats in 1972. During 1982, concentrations of arsenic twice exceeded the recommended drinking water limit of 50 micrograms per liter. Concentrations of other chemical constituents were generally within drinking water limits. Stable-isotope data suggest more than one source of aquifer recharge and indicate some mixing between waters from industrial ponds and local groundwater. Management alternatives are being implemented by two industries for control of groundwater contamination. These include reduction of effluent, installation of liners and leachate recovery systems in ponds, and removal and reclamation of precipitates in old slurry and evaporation ponds. Six sites will be monitored through 1985 to determine changes in groundwater chemistry and migration of contaminants. (USGS)

Water-Resources Investigations Report↗

USGS1982

Ground-water conditions in the eastern part of Michaud Flats, Fort Hall Indian Reservation, Idaho

The Michaud Flats study area occupies about 20 square miles on the Snake River Plain in southeastern Idaho: Ground-water resources are extensively developed for irrigation and industrial uses. The more productive wells are completed in the Pediment Gravel and the basalt flows of the Bighole Basalt and Starlight Formation and the sand and gravel of the Sunbeam Formation. A few shallow domestic wells are completed in the water-table aquifer in the Michaud Gravel. Historically, high levels of arsenic were observed in water from several wells completed in the shallow aquifer. In most wells and springs sampled during this study, levels of arsenic and other minor elements were within limits recommended by the U.S. Public Health Service. Heavy metal concentrations in one well completed in the shallow aquifer, and the concentration of arsenic exceeded the recommended limits. There is some evidence that arsenic, as well as several other minor elements, may occur in above-normal levels naturally in local ground water. Ground water used for irrigation generally has a low sodium-absorption ratio and can be used on almost all soils. All irrigation water sampled have a medium to high salinity hazard, and caution should be used when applying these waters on poorly drained soils. (USGS)

Open-File Report↗