Otter Y.E.A.R.

In the early 1900s, the river otter was nearly extinct in Colorado due to the lack of rules governing the take of wildlife and pollution. The last recorded trapping of an otter occurred in the Yampa River in either 1906 or 1909, according to different accounts. In honor of the 50th anniversary of the first reintroduction efforts, Colorado Parks and Wildlife will celebrate 2026 as the Otter Y.E.A.R. (Yearlong Engagement and Assessment of River Otters).

Submit an Observation

Otter Y.E.A.R.

Submit an Observation

Celebrating 50 Years of Success

Between 1976 and 1991, Colorado reintroduced the species, releasing over 100 otters sourced from healthy populations in other states. Scientists at Colorado Division of Wildlife (now CPW) selected five locations with high-quality otter habitat as release sites: Cheeseman Reservoir, the Gunnison River, the Piedra River, the stretch of the upper Colorado River that runs through Rocky Mountain National Park, and the Dolores River. Around the same time, Utah Department of Wildlife Resources released otters into the Green River near the Colorado-Utah border. Otters from Utah likely dispersed into Colorado, boosting the state’s reintroduction efforts. Surveys since have shown that otters have established breeding populations in many parts of the state, but a statewide, contemporary surveys is needed for a complete understanding of the long-term results of these reintroductions.

Download the 2003 Otter Recovery Plan

Yearlong Engagement and Assessment of River Otters

This year, CPW will document current otter distribution and assess population status. These measurements will be compared with the recovery benchmarks established in CPW’s 2003 Otter Recovery Plan. CPW staff and partner organizations will conduct surveys and submit observations through a unique reporting app.

Join the Effort!

Members of the public can help out, too! If you’d like to help CPW document the progress this species has made, download iNaturalist and find the Otter Y.E.A.R. project to submit observations.

Download iNaturalist

Did You See an Otter?

Because they have similar coloration and live in the same habitats, otters are sometimes confused with other species. Look out for these key physical and behavioral differences when distinguishing otters from swimming mammals.

Otter

Usually swims with only its head and neck visible; sometimes “periscopes,” lifting its head higher above the water
Long, torpedo-like body
Tube-like tail
Total length is 3-4.5 feet, nose to tail
Often in groups
Eats fish and crayfish
Tracks: Five rounded toes, claws usually visible, large 3-4 inch track, webbing may be visible
Scat: fish scales, crayfish, no fur, no berries

Beaver

Rounded body
Bald, wide, flat tail
Usually swims flat on the water’s surface with most of its body length visible
Not often in groups
Sometimes seen carrying branches
More than 3 feet in length, nose to tail
Tracks: Long, thin fingers and toes; webbed rear foot; front and rear feet very different sizes

Muskrat

Rounded body
Bald, rat-like tail
Usually swims flat on the water’s surface with most of its body length visible
Not often in groups
About 2 feet in length, nose to tail
Tracks: Long, thin fingers and toes; front and rear feet different sizes; much smaller than an otter; front ~1”x1”, rear ~2”x2”

Mink

Long body
Tube-like tail
Usually swims flat on the water’s surface with most of its body length visible
Often in groups
1.5-2 feet in length, nose to tail
Tracks: Much smaller than otter, half the size; about 1½“ wide by 1½“ long