Reconnaissance investigation of water quality, bottom sediment, and biota associated with irrigation drainage in Bowdoin National Wildlife Refuge and adjacent areas of the Milk River basin, northeastern Montana, 1986-87

Abstract

Concentrations of trace elements, radiochemicals, and pesticides in the Bowdoin National Wildlife Refuge lakes generally were not substantially larger than those in the water supplied from Dodson South Canal or in irrigation drainage. Concentrations of arsenic uranium and vanadium in Dry Lake Unit, and boron in Lake Bowdoin were notably larger than at other sites. Zinc concentrations in an irrigation drain and two shallow domestic wells were elevated relative to other sites. Concentrations of gross alpha radiation and gross beta radiation were elevated in Dry Lake Unit. Pesticides concentrations at all sites were 0.08 microg/L or less. Water use guidelines concentrations for boron, cadmium, uranium, zinc, and gross alpha radiation were slightly exceeded at several sites. In general, trace-constituent concentrations measured in the water do not indicate any potential toxicity problems in Bowdoin National Wildlife Refuge; however, highwater conditions in 1986 probably caused dilution of dissolved constituents compared to recent dry years. Trace element concentrations in bottom sediment of the refuge lakes were generally similar to background concentrations in the soils. The only exception was Dry Lake Unit, which had concentrations of chromium, copper, nickel, vanadium, and zinc that were about double the mean background concentrations. The maximum selenium concentrationmore » in bottom sediment was 0.6 microg/g. Pesticide concentrations in bottom sediments were less than analytical detection limits at all sites. 46 refs., 13 figs., 22 tabs.« less