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 ug/L; micrograms per liter), uranium (43 ug/
L), and vanadium (51 ug/L) in Dry Lake Unit, and boron (1,000 ug/L) in Lake 
Bowdoin were notably larger than at other sites. Zinc concentrations in an 
irrigation drain (56 ug/L) and two shallow domestic wells (40 and 47 ug/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 ug/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 ug/
g; micrograms per gram), copper (37 ug/g), nickel (37 ug/g), vanadium (160 ug/
g), and zinc (120 ug/g) that were about double the mean background 
concentrations. The maximum selenium concentration in bottom sediment was 
0.6 ug/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 ug/g dry weight) and in potential food items for waterfowl, including the 
vascular plant sago pondweed (810 ug/g dry weight) and plankton (750 ug/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 ug/g dry weight) 
and plankton (13 ug/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.