Carlsbad Irrigation District, McMillan Dam, On Pecos River, 13 miles North of Carlsbad, Carlsbad, Eddy County, NM

Significance: The Pecos Irrigation and Improvement Company constructed McMillan Dam in 1893 as part of an overly-ambitious plan to irrigate hundreds of thousands of acres in the Pecos Valley. The reservoir created by the dam served as the main storage reservoir for the privately funded irrigation project and continued in that capacity after acquisition of the project by the U.S. Reclamation Service in 1905. McMillan Dam is a long, low, rockfill dam faced with a layer of impervious earth. As originally built the structure was 55 feet high with a total crest length of 1,686 feet. The dam's crest was raised in 1911 and 1938. The dam's outlet works (1908-1909) consist of a concrete headgate structure leading to a channel returning to the river. Five sluicegates control the flow of water through the headgates. Two other uncontrolled concrete spillways provide flood protection and a network of earthen embankments help define the reservoir bed.
Survey number: HAER NM-4-A
National Register of Historic Places NRIS Number: 66000476