These consist of planks of wood placed across the canal to form a dam.

A total of 398516yd3 m3 of concrete was poured to form a dam standing 226 ft above the riverbed and 344 ft above foundations.

When the meltwater reaches the freezing air, ice accumulates, forming a dam, and snow that melts later can not drain properly through the dam.

During the last deglaciation, numerous glacial lake outburst floods were caused by the collapse of either ice sheets or glaciers that formed the dams of proglacial lakes.