LAKES OF THE BONNEVILLE BASIN

The Lake Bonneville basin is a major topographic depression covering approximately 52,000 sq mi (134,000 sq km), about a quarter of the Great Basin of the Basin and Range physiographic province and extending into the western edge of the Rocky Mountain physiographic province. Climate change drives fluctuations of closed-basin lakes. Lake Bonneville is the large pluvial lake that existed during glacial time of marine isotope stage 2 and spilled across the rim of the Great Basin into the Columbia River Basin. Great Salt Lake is the shallow, highly saline, interglacial lake that presently occupies the lowest areas of the basin.

Increased surface water, ground water, and precipitation onto the lake surface increase lake volume as do some changes in basin configuration. For example, the Bear River that presently provides about half of the inflow to Great Salt Lake formerly drained to the Snake River and on to the Pacific Ocean. Basalt flows apparently diverted the Bear River south into the Bonneville Basin prior to the rise of Lake Bonneville.

Human activities impact lake configuration, stream inflow, and lake evaporation. Conversely, Great Salt Lake impacts Wasatch Front communities. The lake limits westward expansion of some communities; impacts weather and air quality; affects tourism; provides resources of salt, brine shrimp eggs, and wetlands; and, on occasion, damages structures built on its lake bed. The wet cycle of the 1980s caused the lake to rise to historic high levels of the 1860s-1870s. Strategies to control lake flooding included diking portions of the lake to protect property; diverting the Bear River to the Snake River drainage to decrease surface inflow; increasing evaporation by changing lake albedo; and pumping into the Great Salt Lake Desert to decrease the volume of water in the main bodies of the lake and to increase evaporation.

People living around Great Salt Lake find it difficult to accept that fluctuations are essential to the health of the lake.