In the past, this subspecies was found throughout portions of the Colorado River drainage in
Wyoming,
Colorado,
Utah,
Arizona, and
New Mexico. However, recent estimates suggest this subspecies occupies around 14% of its historic range. Colorado River cutthroat trout are thought to have occupied the basin of upper Muddy Creek, a tributary of the
Little Snake River (which ultimately flows into the
Colorado River) in southern
Carbon County,
Wyoming. Historical accounts in letters and diaries refer to them as "mountain trout" or "speckled trout." The fish may have begun to disappear from the upper Muddy Creek in the 1850s as a result of physical changes made to the environment by travelers, the introduction of the
brook trout and other non-native species, and possibly the over-trapping of
beavers, which affected dams and dependent habitats. A distinct lineage of Colorado River cutthroat trout known as the San Juan cutthroat was also found in the
San Juan River and its tributaries, and was identified in 2012 by
genetic testing of two specimens collected in 1874 near
Pagosa Springs. While feared extinct, 8 isolated populations were discovered in and around the
San Juan National Forest in mid-2018. Shortly after the rediscovery of the San Juan cutthroat, their remnant populations were threatened by the
416 Fire, which was closing in on their remaining habitat. In response, 58 San Juan cutthroats were removed from two remote creeks north of
Durango and are being held in hatcheries, with the ultimate goal of
captive breeding and reintroduction. ==Conservation==