Lee Metcalf National Wildlife Refuge 



Climatic setting. The net annual precipitation balance for the Lee 

 Metcalf NWR (from the MAPS database) is -24 inches, near the more 

 strongly evaporative extreme for sites in the intermontane valleys 

 and in western Montana generally. Mean monthly precipitation for 

 the Western Agricultural Experiment Station (near Stevensville) 

 shows a relatively broad distribution with a maximum in May. The 

 3-year moving average of annual precipitation totals for the 

 Western Ag Station was below the long-term average from 1985 to 

 1992. In 1993 (the year prior to sampling) precipitation exceeded 

 the long-term average by about 2.5 inches. Data for 1994 (the year 

 of sampling) were not retrieved; regionally, 1994 totals were below 

 average . 



Geologic setting. The Lee Metcalf Refuge is underlain by permeable 

 alluvium of the Recent Bitterroot River floodplain. Alluvial 

 terraces of the Bitterroot River and floodplain and fan deposits 

 of tributary streams border the refuge. Glaciof luvial gravels and 

 fine-grained Tertiary-aged sediments underlie the Holocene alluvium 

 at depth and form elevated benches to the east. Shallow water 

 table depths and ground-water discharge areas occur beneath and 

 around the refuge, contributing some of the water budget of the 

 wetland complex. 



Hydrologic type. The Lee Metcalf site is an artificial impoundment 

 holding both natural ground-water discharge and imported water from 

 the Burnt Fork and Threemile Creek drainage. The impounded wetland 

 sampled at site WET45 has surface water outflow and probably also 

 has ground-water outflow under at least some conditions. 



Basin characteristics. The natural surface catchment of the WET45 

 wetland is relatively small. The natural surface catchment is 

 little importance to the site's water balance, however, since most 

 water is contributed either by ground water in probable connection 

 with the Bitterroot River, or by surface water imported from 

 tributary drainages. Water depths are not available, but are 

 probably quite shallow. 



Water chemistry. At the time of sampling, the Lee Metcalf wetland 

 contained dilute water of mixed cation-bicarbonate composition and 

 high (biologically influenced) pH. Equilibrium calculations 

 indicate oversaturation with carbonate minerals under the high pH 

 conditions measured. Ammonium, nitrate and orthophosphate 

 concentrations were below reporting limits, and total phosphorous 

 and total organic carbon concentrations were near the lower end of 

 the ranges shown for sites in any class. 



Arsenic and iron (both reported at their detection limits) and 

 copper concentrations were at the lower end of the ranges shown by 

 sample sites within this class. Most other trace element 

 concentrations were below reporting limits. 



