Even the best ditch could not deliver water if the river lacked flow. The Poudre surged with springtime snowmelt for a few months, only to have insufficient flows later in the season. Northern Coloradoans needed to store the abundant spring flow ; reservoirs provided a solution.
As the snow melted, these artificial lakes held the water and allowed junior water right holders to release water from their reservoirs to senior water right holders in exchange for the junior water holders being able to divert a like amount of water from the Poudre.
In 1875, Fort Collins’ Warren Lake became the Poudre valley’s first irrigation reservoir. Steady reservoir expansion continued into the twentieth century.