Beaver Creek Wetland 



Climatic setting. The net annual precipitation balance for the 

 Beaver Creek site (from the MAPS database) is -6 inches, placing 

 the site near mid-range in evaporative intensity for Rocky Mountain 

 sample sites. [At absolute values in this range, the "annual 

 precipitation balance" should definitely be considered only a 

 relative scaler of evaporative intensity, not an indicator of the 

 true sign of the site's moisture balance.] Mean monthly 

 precipitation for the Seeley Lake Ranger Station climatic station 

 shows a bimodal distribution with the primary peak in January and 

 a secondary June maximum. The 3-year running average at Seeley 

 Lake shows an apparent periodicity in annual precipitation, with 

 a period of five to six years. Since the early 1970 's, the three- 

 year average has been mainly below the average for the period of 

 record. Total precipitation in 1993 (the year prior to sampling) 

 was about 3 inches below average. 



Geologic setting. The Beaver Creek site is underlain by till (and 

 other glacial sediments?) deposited by the late Pleistocene advance 

 of glacial ice down Placid Creek. The texture of the till in the 

 general area is described as sandy; soil drainage, however, is 

 described as poor. Bedrock formations underlying the area inferred 

 to have contributed glacial sediments to the site include mainly 

 noncalcareous formations of the late Proterozoic Belt series. 



Hydrologic type. The Beaver Creek wetland is an apparent kettle 

 lacking discrete surface water inflow or outflow. Mineral 

 equilibria (see below) may reflect either a ground-water recharge 

 position for this site, or a lack of carbonate lithologies in local 

 geologic materials. 



Basin characteristics. The WET03 site is one of a cluster of 

 poorly integrated depressions forming a stepwise profile across an 

 interfluvial plateau. Ground-water flow between depressions is 

 inferred from the lack of surface drainage and dilute water quality 

 of the sample site. The calculated ratio of catchment to wetland 

 area is toward the higher end for sites included in this type; the 

 surface catchment used, however, does not discriminate small 

 internally drained areas and so may not be meaningful to the 

 hydrology of the wetland site. Road construction may have altered 

 drainage from this wetland. 



Water chemistry. The Beaver Creek wetland displays very dilute 

 calcium bicarbonate chemistry. The measured total dissolved solids 

 concentration was among the lowest in the sample set. Mineral 

 equilibria indicate substantial undersaturation with carbonate 

 species. Phosphorous concentrations were near the low end of the 

 range for all sample sites, nitrate was below detection limits, and 

 the ammonium concentration was mid-range for hydrologically similar 

 sites. The total organic carbon concentration was among the upper 

 50% of hydrologically similar sample sites. 



