explorer Juan Maria de Rivera of Santa Fe recorded the name "Rio de las Animas" in 1765. One theory is that the full name of the river was once "Rio de las Animas Perdidas", although this idea may indicate confusion with the Purgatoire River of southeastern Colorado.
The ancestral Puebloan site of Aztec Ruins National Monument is situated along the river in the present day town of Aztec and for much of its course the river flows through native Ute and Navajo lands.
Engineering and development
Numerous irrigation ditches serve the surrounding farmland along the river. The Durango Pumping Plant, completed in 2011, as part of the Animas-La Plata Water Project, draws an average annual of 57,100 acre-feet from the river, for storage in Lake Nighthorse.
Wildlife and plants
The Animas serves as habitat to resident and migratory bald eagles which arrive in the winter months to take advantage of the ice-free river.
2015 contaminants spill
In August 2015, the La PlataCounty Sheriff's Office closed the river to the public after a crew working for the EPA released approximately 3 million gallons of mine waste into Cement Creek, a tributary of the Animas. The plug was accidentally removed while investigating a leak at the abandoned Gold King Mine. The mine was last active in the 1920s, but it had been leaking toxic water at a rate of 50 to 250 gallons a minute for years. The spill contained the toxic metalsarsenic, cadmium, and lead, as well as the metals aluminum and copper. There may be other toxic heavy metals in the plume. The spill changed the color of the river to orange, and the spill was described as "devastating" by Kim Stevens, the director of Environment Colorado, who said that businesses who rely on the river for profit might have to close down. The river's fish population might also be at risk due to the toxic waste that now runs through the river. In February 2016, the Associated Press reported that the spill "dumped 880,000 pounds of metals" into the Animas River, and that "most of the metals settled into the riverbed." The metals considered are "cadmium, copper, lead, mercury, nickel, zinc, and possibly others."
Recreation
The Animas river is a major white water rafting attraction accounting for 8.9% of Colorado's commercial rafting market while annually generating 45,411 commercial user days and direct expenditures of $5,207,033. The Animas is a freestone fishery well populated with rainbow, brown, Colorado River cutthroat, and brook trout. It is considered a gold medal fishery above Rivera Bridge Crossing in Colorado. Recreational fishing with artificial lures and flies on the Animas is available year-round due to moderate winter weather. Insect hatches of aquatic diptera and mayflies occur in the winter and spring months. In late spring, summer and through fall the Animas sees caddisfly and mayfly hatches as well as terrestrials such as grasshoppers. Animas trout average. Larger trout in the are occasionally caught by anglers. Brown trout as large as have been caught in the Animas.