Schrammeck Lake WPA 



Climatic setting. The net annual precipitation balance for 

 Scranuneck Lake (from the MAPS database) is -25 inches, an 

 intermediate value for hydrologically similar sampling sites. 

 Monthly average precipitation for the Cascade climatic station 

 shows a strong May-June peak. Annual records for the Cascade 

 station show the 3-year running average at or above the long-term 

 average for most of the past 20 years. The annual total in 1993, 

 the year prior to sampling, exceeded the long-term mean by about 

 3 inches. 



Geologic setting. The Schrammeck Lake basin is underlain by 

 bentonitic shale and sandstone of the Colorado group. Colorado 

 Group sediments in the area reportedly include pebble conglomerates 

 derived from the phosphatic Phosphoria Formation. 



The area is beyond the maximum advance of Pleistocene glaciation. 

 Surficial sediments observed in and around the lake include 

 lacustrine sediments ranging from organic-rich, highly reduced 

 sticky mud to relatively well-sorted, fine to medium-grained 

 calcareous littoral sand on the northern shoreline. Vegetated 

 ridge-and-swale features at the northern end of the lake may be 

 small dunes, suggesting past desiccation of the lake. The lake 

 exhibits at least one relict shoreline at an elevation 

 approximately 10 feet above the observed lake stage, indicating 

 lake volume more than an order of magnitude greater than at the 

 time of sampling. In nearby Geyser Creek, groundwater discharge 

 reportedly causes small "eruptive" features in weathered Colorado 

 Group sediments. 



Hydrologic type. Schrammeck Lake is a nonglaciated (probably 

 structurally controlled) basin lacking surface outflow. Surface 

 outflow has probably occurred at higher water levels, shown 

 topographically by an apparent outflow channel north of the 

 wetland. Ground-water outflow through winnowed littoral sediments 

 may occur. 



Basin characteristics. Schrammeck Lake has a relatively small 

 surface catchment with respect to the area of the wetland. At 

 current water levels the volume of Schrammeck Lake is low relative 

 to it's surface area. The maximum measured water depth in August 

 of 1994 (at somewhat lower stage than during sampling) was 1.4 

 feet, with little variability across the open water portion of the 

 basin. 



Water chemistry. Schrammeck Lake water is a sodium carbonate type, 

 of moderate salinity at the time of sampling. This major-ion water 

 composition is unigue within the wetland sample set. Eguilibrium 

 calculations indicate substantial oversaturation with carbonate 

 species. 



Schrammeck Lake shows relatively high water-column concentrations 

 of several trace elements, including boron, chromium, iron, lead 



