While irrigators built more and larger reservoirs, they still depended on the Poudre River to fill their lakes. A dry year on the Poudre meant reservoirs and ditches ran low. Locals continued to search for new sources of water up in the mountains. The Poudre’s headwaters lie fairly close to those of several other river basins. Investors saw potential; with high elevation ditch-digging, snowmelt that drained into other river basins could be diverted into the Poudre. Today, about ten percent of the Poudre’s flow originates in other basins.
Perhaps the best-known trans-mountain diversion is the Grand River Ditch. Named in the nineteenth century when the Colorado River was called the Grand River, the ditch developed over a period of 44 years and extended 17 miles. This high country trench reroutes Colorado River water and carries up to five hundred cubic feet per second.