Over the roughly 65,000 years that Lake Bonneville existed, sediments built up, creating a lacustrine plain over Utah Valley. As a result, the valley floor and lake bed are relatively flat, which causes the lake to be shallow. The lake has a maximum depth of just under and an average depth of about . This shallowness allows winds to easily stir up sediments from the lake's bottom, contributing to the turbidity or the impression of pollution seen in Utah Lake's water.