Beindy Reservoir 



Climatic setting. The net annual precipitation balance for the 

 Bandy Reservoir site (from the MAPS database) is -15 inches, 

 placing the site toward the more humid end of the range for 

 hydrologically and regionally similar sites. Monthly average 

 precipitation for the Ovando 9 SSE climatic station shows a bimodal 

 distribution, with a primary June peak and a secondary January 

 peak. The 3-year moving average of total annual precipitation 

 remained below (often considerably below) the long-term average 

 from the mid-1970s through 1993. The total precipitation for 1993 

 (the year prior to sampling) was very near the long-term average. 



Geologic setting. Bandy Reservoir is underlain by calcareous late 

 Pleistocene till deposited by ice advancing down Monture Creek from 

 sources in the Swan Range. Bandy Reservoir lies along the kettle- 

 pocked lateral moraine marking the westward extent of the Monture 

 advance. The till is described as variable in texture and may 

 overlie glacial deposits (including outwash) deposited by the 

 slightly earlier Clearwater glacial advance. Fine-grained Tertiary 

 aged valley fill deposits underlie glacial deposits at unknown (but 

 probably shallow) depths. 



Bedrock geologic units in the source area for sediments deposited 

 by the Monture advance include several distinct formations of the 

 Proterozoic-aged Belt series; large areas are underlain by the 

 calcareous and dolomitic Helena Formation. 



Hydrologic type. Bandy Reservoir is an artificial impoundment of 

 a natural basin that probably had a prior history as a smaller 

 natural water body. Presently it provides off -stream storage of 

 water diverted from Shanley Creek. Discharge is back to Shanley 

 Creek (and to local irrigated areas?). Water levels are 

 manipulated for irrigation storage purposes, and probably do not 

 reflect natural water level fluctuations of unmanipulated nearby 

 lakes. 



Basin characteristics. The natural (closed) catchment of Bandy 

 Reservoir is small and probably supported only a minor (perhaps 

 seasonal) pond or wetland similar to many others along the Monture 

 moraine. As a reservoir, it receives inflow from a large catchment 

 and has a relatively high catchment to wetland area ratio. 

 Diversion rates and lake volume are unknown, but the flux of water 

 through the reservoir is probably relatively rapid. 



Water chemistry. At the time of sampling, Bandy Reservoir 

 contained dilute ("fresh") but highly alkaline calcium- 

 magnesium/carbonate water. Equilibrium calculations indicate 

 oversaturation with carbonate species at the sampled pH. 

 Phosphorous, nitrogen and total organic carbon concentrations were 

 near the low end of the ranges for hydrologically and regionally 

 similar sites. Most trace element concentrations were below 

 detection limits. Arsenic and copper were found at concentrations 



