Typically, the Native Americans built dams across the river or other tributary streams in the spring out of materials including boulders, dirt, reeds, grass or other elements. The watercourse below the dam would then be desiccated, and the water led by canal to the irrigated plot of land, typically no more than a few square miles. Directly after the dam was closed and the river dried up, fish trapped on the dry riverbed would then be gathered and eaten. Before winter storms caused floods, the dam would be breached, allowing the river to flow naturally again, while fish would be collected in the dried-up river channel. By then, there would be enough food stored to last the winter in which the cropland would lie fallow.