Earth Sciences Report 1977-01

Hydrogeology of the Lesser Slave Lake Area, Alberta

Executive Summary

The hydrogeology of the Lesser Slave Lake area (NTS 83O) is described. Data are unevenly distributed and have been supplemented with field observations and a test drilling program during 1974. A large amount of interpretation was involved in the construction of the hydrogeological map and profiles.

The most important aquifers in the area are basal or near-basal sands and gravels occurring in preglacial drainage networks. They have been assigned a 20-year safe yield of 25 to 500 igpm (approximately 2 to 38 l/sec).

The most important bedrock aquifers are sandstones and coals of the Wapiti Formation which have been assigned a 20-year safe yield of 5 to 25 igpm (approximately 0.4 to 2 l/sec).

Water chemistry is variable and total dissolved solids contents range from 200 to 2000 ppm in the drift and non-marine strata. Iron concentrations are usually very high. Groundwaters are generally of the Ca or Na/HCO3 +C03 type with local areas of (1) Ca or Na/SO4 types attributed to high sulfate contents in till, and (2) Na+Ca/Cl types attributed to contamination from deeper marine strata. These deeper marine rocks contain highly saline waters of the Na/Cl type.

Place Keywords: 83o; alberta; lesser slave lake

Theme Keywords: bedrock aquifer; hydrogeology