**National Irrigation Water Quality Program**\
U.S. Department of the Interior

Reconnaissance Investigation of Water Quality, Bottom Sediment, and
Biota Associated with Irrigation Drainage in the Bowdoin National
Wildlife Refuge and Adjacent Areas of the Milk River Basin, Northeastern
Montana, 1986-87

J.H. Lambing, U.S. Geological Survey\
W.E. Jones, U.S. Fish and Wildlife Service\
J.W. Sutphin, U.S. Bureau of Reclamation

ABSTRACT

Water, bottom sediment, and biota were sampled in 1986 at Bowdoin
National Wildlife Refuge and adjacent areas of the Milk River basin in
northeastern Montana. This report describes the results of a study
conducted to determine concentrations of selected trace elements,
radiochemicals, and pesticides in water, bottom sediment, and biota, and
to compare the analytical\
results to various guidelines for environmental protection and to
available baseline information.

Concentrations of trace elements, radiochemicals, and pesticides in the
refuge lakes generally were not substantially larger than\
those in the water supplied from Dodson South Canal or in irrigation
drainage. Concentrations of arsenic (47 µg/L; micrograms per liter),
uranium (43 µg/L), and vanadium (51 µg/L) in Dry Lake Unit, and boron
(1,000 µg/L) in Lake Bowdoin were notably larger than at other sites.
Zinc concentrations in an irrigation drain (56 µg/L) and two shallow
domestic wells (40 and 47 µg/L) were elevated relative to other sites.
Concentrations of gross alpha radiation (64 picocuries per liter) and
gross beta radiation (71 picocuries per liter) were elevated in Dry Lake
Unit. Pesticide concentrations at all sites were 0.08 µg/L or less.
Water-use guideline 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 (99
µg/g; micrograms per gram), copper (37 µg/g), nickel (37 µg/g), vanadium
(160 µg/g), and zinc (120 µg/g) that were about double the mean
background concentrations. The maximum selenium concentration in bottom
sediment was 0.6 µg/g. Pesticide concentrations in bottom sediments were
less than analytical detection limits at all sites.

With few exceptions, concentrations of trace elements and pesticides in
biota generally were less than values known to produce harmful effects
on growth or reproduction. Boron concentrations in two coot livers (140
µg/g dry weight) and in potential food items for waterfowl, including
the vascular plant sago pondweed (810 µg/g dry weight) and plankton (750
µg/g dry weight), were at levels associated with adverse reproductive
effects. Selenium concentrations in most organisms sampled were
indicative of noncontaminated conditions; however, selenium
concentrations in some samples of waterfowl dietary items such as
macroinvertebrates (6.5 µg/g dry weight) and plankton (13 µg/g dry
weight) were near levels producing detrimental effects. Several other
trace elements were present in biota at concentrations that were
potentially elevated in comparison to the general\
range of values among the sampling sites, but no particular site or
trophic level of biota consistently had unusually large concentrations.
Pesticide concentrations in biota were small, relative to available
toxicity data, at all sites.