Today the Bear River is directed into Bear Lake to maintain the lake as a reservoir. Without the river water, Bear Lake's level would be entirely
maintained by water from springs and runoff of rain and snow. Part of our study is to identify past changes in climate by looking for evidence
of higher and lower lake levels before the reservoir maintenance began in AD 1912. We will look at diatoms,
pollen, geochemistry, isotopes and
grain-size to find evidence of changing environments linked to water level.Previous studies have found evidence of several higher-than-today shorelines, seen as bench-like features in the Bear Lake Valley. The town of Garden City is just above one of these terraces, formed about 7700-8200 years ago. At times of high water, Bear Lake's length increased from 30 km (about 18 miles) to 82 km (51 miles), almost all to the north. The higher lake levels have been estimated at 25 ft above today's level (Williams and others, 1962), but our surveys in 1998-99 suggest that the lake may have reached as high as 75 ft above present levels (Reheis, oral commun., 2000). These very high levels may have occurred early on, about 130,000-600,000 years ago. We are using amino acid dating of lake fossils in these high terraces to determine their age.
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