The Grand Ditch, also known as the Grand River Ditch and originally known as the North Grand River Ditch, is a water diversion project in the Never Summer Mountains, in northern Colorado (United States). It is long, wide, and deep on average. Streams and creeks that flow from the highest peaks of the Never Summer Mountains are diverted into the ditch, which flows over the Continental Divide at La Poudre Pass at , delivering the water into Long Draw Reservoir and the Cache La Poudre River for eastern plains farmers. The water would otherwise have gone into the Colorado River (formerly known as the Grand River, from which the name of the ditch is derived) that flows west towards the Pacific; instead, the Cache La Poudre River goes East and through the Mississippi River discharges into the Gulf of Mexico.