Animas-La Plata

La Plata County, Colorado



A very large archaeological project preceded the Bureau of Reclamation’s Animas-La Plata Project, which constructed a dam and Lake Nighthorse Reservoir in Ridges Basin, just south and west of Durango. Congress authorized the project in 1968, and the resulting 1,490 acre-reservoir was filled in 2013.


The many delays to the project were caused, in part, by increasing environmental awareness — including concerns for cultural resources and the environment. The archaeology project was conducted in the early 2000s under a multi-year, multi-million dollar subcontract between the Ute Mountain Ute Tribe’s Weeminuche Construction Authority and SWCA, an environmental consulting firm headquartered in Phoenix, Arizona with offices in Broomfield, Fort Collins, and Durango.


SWCA investigated 74 archaeological sites ranging in date from 7,500 BC to European-American sites occupied from the late 19th century to 1950. Most of the sites dated to the early Pueblo I period (A.D. 750 to 825).


SWCA established a full archaeological laboratory in Durango to meet the obligations of their contract. The lab supported field investigations, analyzed materials, and prepared data and materials for curation at the Canyons of the Ancients Visitor Center and Museum. Today Lake Nighthorse is managed by the Bureau of Reclamation and the City of Durango, providing water to local communities and Tribes, and offering recreational opportunities including swimming, boating, and fishing.