Dickinson Irrigation, also known as Rock Ranch, is a private water resource structure located in Sedgwick, Colorado. Completed in 1906, this earth dam serves multiple purposes including irrigation, fire protection, stock watering, and small fish pond management. The dam has a height of 32 feet and a length of 569 feet, with a storage capacity of 166 acre-feet and a drainage area of 3 square miles.

Despite its historical significance, Dickinson Irrigation faces challenges with an unsatisfactory condition assessment as of December 2011. The dam has a low hazard potential but is classified as having a moderate risk due to its age and condition. The spillway, with a width of 93 feet, is uncontrolled, and the last inspection took place in 2011 with a recommended frequency of every 6 years.

Managed by the private owner, this dam on the South Platte River-TR has state regulation and oversight, with permitting, inspection, and enforcement in place. With its rich history and vital role in water management for agriculture and wildlife in the region, Dickinson Irrigation represents a key piece of Colorado's water infrastructure that requires ongoing monitoring and maintenance to ensure its continued safe operation.