Grand Coulee Dam south, enclosed and created Banks Lake, which covered the northern of the Grand Coulee. Additional dams, such as the Pinto and O'Sullivan Dams, were constructed alongside siphons and canals, creating a vast irrigation supply network called the Columbia Basin Project. Irrigation began between 1951 and 1953 as six of the 12 pumps were installed and Banks Lake was filled. After World War II, the growing demand for electricity sparked interest in constructing another power plant supported by the Grand Coulee Dam. One obstacle to an additional power plant was the great seasonality of the Columbia River's streamflow. Today the flow
Grand Coulee Dam and during construction, workers and engineers experienced problems. Contracts for companies to construct the various parts of the dam were difficult to award as few companies were sizable enough to fill them. This forced companies to consolidate. In addition, Native American graves had to be relocated and temporary fish ladders had to be constructed. During construction additional problems included landslides and the need to protect newly poured concrete from freezing. Construction on the downstream Grand Coulee Bridge began in and more considerable earth-moving began in August. Excavation for the dam's foundation required the removal of of dirt and stone. To