The Experimental Lakes Area (ELA) is located at 93°30′–94°00′W and 49°30′–49°45′N at an altitude of 360–380 m above mean sea level. This area is underlain by Precambrian acid granites overlain in some areas by thin glacial drift composed largely of sand and gravel of quartz, plagioclase, and K-feldspar. The area was under glacial ice about 14,000 years B.P. (before present). With the melting of this glacial ice, ELA was situated on the eastern margin of glacial Lake Agassiz. As Lake Agassiz levels receded, the present lake basins were formed. The ELA watersheds now drain into the Winnipeg River, which is in the Hudson Bay drainage system.Mean annual temperatures in the vicinity of ELA are between 0.5 and 2.2 C, and annual precipitation is between 500 and 750 mm. Brunisols were observed over sand deposits in the ELA, but considerable variation in soil types and soil depth were also found. ELA is in a boreal (fire-controlled) subclimax forest of jack pine, black spruce, trembling aspen, and white birch. Aquatic macrophytes were scarce in the littoral zone of ELA lakes. Nearby logging operations and hunting and sport fishing have not influenced the immediate watersheds of ELA lakes.Morphometric maps and measurements are given for 16 lakes in ELA. These lakes vary from 2.5 to 33 m in maximum depth, and from 1.7 to 56 ha in lake surface area. Using estimates of precipitation, evaporation, evapotranspiration, drainage areas, and lake morphometry, a preliminary calculation of theoretical water renewal time is given for these lakes. These values range from 2.6 to 38 years.