Glacial Lake Columbia Glacial Lake Columbia Glacial Lake Columbia was the lake formed on the ice-dammed Columbia River behind the Okanogan lobe of the Cordilleran Ice Sheet when the lobe covered of the Waterville Plateau west of Grand Coulee in central Washington state during the Wisconsin glaciation. Lake Columbia was a substantially larger version of the modern-day lake behind the Grand Coulee Dam. Lake Columbia's overflow – the diverted Columbia River – drained first through Foster Coulee, and as the ice dam grew, through first Moses Coulee, and finally, the Grand Coulee. The Cordilleran ice sheet also blocked the Clark Fork River and
Grand Coulee Dam Wenatchee. Together, they became known as the "Dam College". Woods began promoting the Grand Coulee Dam in his newspaper, often with articles written by O'Sullivan. The dam idea gained popularity with the public in 1918. Backers of reclamation in Central Washington split into two camps. The "pumpers" favored a dam with pumps to elevate water from the river into the Grand Coulee from which canals and pipes could irrigate farmland. The "ditchers" favored diverting water from northeast Washington's Pend Oreille River via a gravity canal to irrigate farmland in Central and Eastern Washington. Many locals such as Woods, O'Sullivan and