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Closed Basin

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Closed basins represent tractable systems for investigating hydrologic processes over large areas. The Great Salt Lake (GSL) stands out as a collector and integrator of signals from climatic and anthropogenically-induced hydrologic change. These changes are recorded in ancient lake terraces, accumulated sediments, short-term lake level changes, and recent changes in lake water chemistry.

About 15,000 years ago a large and deep lake, called Lake Bonneville, covered much of northern Utah. The shoreline of this ancient lake is preserved in many locations throughout the Great Salt Lake Basin, and is an important geologic feature of the Wasatch Front as well as one of the most striking topographic and scenic fixtures of the region. The terraces that make up the remnant of the shoreline hold valuable information about long term changes in climate within the region.

Terraced mountains in Logan, Utah Photograph of Lake Bonneville shoreline terraces just south of Utah State University in Logan. In this picture, houses have been built on one of the lower terraces, and a higher terrace can be seen above.

Sediment cores collected in the Great Salt Lake also provide a record of climatic and anthropogenic changes that have occurred within the basin. The following figure shows an example - polycyclic aromatic hydrocarbon (PAH) levels in lake sediments have increased as population has increased over the past half century.

Distribution of PAHs in relation to population in Salt Lake County, Utah Vertical distribution of total polycyclic aromatic hydrocarbons (PAHs) in a gravity core from Farmington Bay, and relation to population growth in Salt Lake County, Utah. (USGS, 2004).

Reference: USGS. 2004. Trace Elements and Organic Compounds in Sediment and Fish Tissue from the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998-1999. National Water-Quality Assessment Program. Water-Resources Investigations Report 03-4283.

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