Coal Ridge Waste Dam #1, also known as Sand Hill Lake, is a privately owned structure located in Weld County, Colorado, near the city of Platteville. Built in 1954 for irrigation purposes, this earth dam stands at a height of 31 feet and has a hydraulic height of 25 feet. The dam has a storage capacity of 1189 acre-feet, with a normal storage of 591 acre-feet and a surface area of 81 acres.

With a significant hazard potential and a satisfactory condition assessment as of July 2020, Coal Ridge Waste Dam #1 is regulated by the Colorado Department of Water Resources. The dam has an uncontrolled spillway with a width of 242 feet and a maximum discharge rate of 9290 cubic feet per second. The structure has been modified in 2001 for hydraulic purposes, and regular inspections are conducted, with the last one taking place in July 2020.

For water resource and climate enthusiasts, Coal Ridge Waste Dam #1 presents an interesting case study of a private irrigation dam in Colorado. Its location near the South Platte River and its association with recreational activities make it a vital part of the local water management infrastructure. With a moderate risk assessment and a history of satisfactory condition, this dam serves as a reminder of the importance of maintaining and monitoring such structures to ensure the safety of both the surrounding community and the environment.