Milliron Reservoir Number 1 is a reservoir located in Dawson County, Montana. It appears on the Cluster Buttes NW USGS 7.5-minute topographic quadrangle. The elevation at this location is approximately 2,301.80 feet (701.59 m) above sea level. The nearest populated place is Lufboro (historical), approximately 7.9 miles to the NNW.