Most life was wiped out, and the creatures that did survive huddled in small pockets of open water, where hot springs continued to bubble up. This was Snowball Earth â a deep freeze that began around 715 million years ago and held Earth in its icy grip for a good 120 million years. There are no other comparable glacial periods on Earth.
Lake Barkley Lake Levels. The lake's level is fluctuated from summer to winter for flood control purposes. Summer pool (359 ft. sea level) is normally reached by May 1. The water level begins dropping gradually on July 1, and winter pool (354 ft.) is reached by December 1.
Dworshak Reservoir is the name of the lake formed behind the dam. At normal maximum water levels of 1,600 feet (490 m) above sea level, the reservoir stretches 53 miles (85 km) upstream, covering 17,090 acres (69.2 km2) and containing 3,468,000 acre feet (4.278 km3) of water with 175 miles (282 km) of shoreline.