Skaha Lake is the fourth of the chain of five major lakes which occupy portion of the Okanagan Valley in the interior of British Columbia. The Okanagan Valley is a structural trench overlying a system of sub-parallel linked faults that separate the late Paleozoic or early Mesozoic Monoshee group of metamorphic rocks of differing lithology but of similar age. The trench is partially filled with several hundred meters of unconsolidated material (400 m in the Skaha Lake area). It is likely that the unconsolidated material was deposited in association with early glaciations of the Pleistocene Epoch. It seems probable that during the Pleistocene the valley was the site of deposition resulting from glacial outwash, direct glaciation and lacustrine fluvial sedimentation. During deglaciation a number of terraces were formed as lowering of post glacial lake levels was repeatedly arrested.

Prominent silt and clay cliffs border Skaha Lake as a result of this period of glacial down-washing and degradation. Deglaciation was well advanced by 9750 B. P. and the lakes of Okanagan valley were formed about 8900 B. P.

Skaha Lake is comprised of two distinct basins separated by a bedrock sill at a depth of 24 m. The surrounding watershed has "benches" (terrace) along the east and west shores which rise to mountainous slopes with the flat valley bottom at the north and south ends. Skaha Lake is separated from Okanagan Lake to the north by a narrow stretch of valley bottom on which the city of Penticton has developed.

The watershed of Skaha Lake was first settled by Europeans in the last half of the 19th century. The climate (dry warm summers) and soil and availability of irrigation water led to the development of a substantial tree fruit industry around the lake and throughout the valley. Logging occurs in the upper elevation forests of the valley. The lower elevation vegetation of the Skaha Lake watershed is described as a Ponderosa pine (Pinus ponderosa)/bunchgrass community and the higher elevation is dominated by Douglas fir (Pseudotsuga menziesii) forest.

Little limnological information was collected prior to 1969 when the Okanagan Basin Study was undertaken. Initiative for this comprehensive program came about primarily due to complaints to deteriorating water quality in Skaha Lake as a result of sewage discharge from the city of Penticton to the Okanagan River draining into Skaha Lake. Tertiary treatment was undertaken in 1971. Water quality subsequently improved.

The lake is highly utilized as summer recreation location and tourism is presently a major component of the local economy (Q, 2).