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Wood Lake NAM-52

Riparian Nation(s) Canada
Lat. 50°05' N Lng. 119°23' W Alt. 391 m
Surface Area 9.3 km2 Mean Depth 21.5 m Volume 0.19 km3
Shoreline 13.5 km Catchment Area 190 km2 Residence Time 16.9 yr
Frozen Period Dec-Feb   Mixing Type Monomictic   Morphogenesis/Dam  
Related Info/Site  

Description

Wood Lake is the first (uppermost) of the chain of five major lakes which occupies portions 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 group of metamorphic rocks of differing lithology but of similar age. The trench is partially filled with up to several hundred meters of unconsolidated material. In the Wood Lake area this material is approximately 125 m thick under the centre of Wood Lake. It is likely that the unconsolidated material was deposited in association with earlier glaciations of the Pleistocene Epoch. Glaciation was well advanced by 9750 B. P. and the lakes of the Okanagan Valley were formed by about 8900 B. P.

Wood Lake has a simple "bath tub" shaped basin. This morphometry makes it very suitable for a variety of investigations, particularly the internal physical structure and mass balance study. The natural water residence time is quite long (30 years) and this may be a factor in the generally eutrophic conditions.

The watershed was first settled by Europeans in the last half of the 19th century. The climate (dry warm summers), well drained soils and availability of irrigation water led to the development of a substantial tree fruit industry around the lake and throughout the valley. The upper watershed is heavily forested (predominantly Douglas fir, Pseudotsuga menziesii) and has been logged for several decades. The lower elevation of the watershed is described as a Ponderosa pine (Pinus ponderosa)/bunchgrass community.

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 of poor water quality in Wood Lake and deteriorating water quality in Skaha and Osoyoos Lakes.

Wood Lake has displayed some remarkable changes in the past 20 years. Wood Lake is immediately adjacent to Kalamalka Lake, a larger oligotrophic marl lake, and connected to it by a dredged channel (the Oyama canal). The two lakes have generally demonstrated a dramatic side-by-side contrast in nutrient water chemistry and biological production. Wood Lake was, during the intensive study of the Okanagan Basin Study, described as eutrophic with summer cyanobacterial blooms and large hypolimnetic oxygen depletion. Recent water quality has improved with much better water clarity and other changes. Cooling water taken from Okanagan Lake is used by a distillery in the Wood Lake basin and flows into Wood Lake have reduced the normal water residence time of the lake by half. This change in water residence time as well as other hydrologic and climatic trends may play a role in the water chemistry changes noted in recent years.

During the 1970's, Eurasian milfoil (Myriophyllum spicatum) colonized significant portions of the littoral zone, especially in the shallower southern end of the lake. Combinations of dredging and herbicide treatments have been employed from time to time to limit this nuisance (Q, 2).

Photo of Wood Lake
Photo: R. N. Nordin