In1976 river otters were reintroduced on the South Platte river. The river otter is found in streams and rivers in Rocky Moutain National Park, Cache la Poudre River and the upper reaches of the Colorado River. In the past, otters lived all over the state but now they are quite rare. Otters are part of the weasel family. The otter's scientific name is lutra canadensis .
Otters can swim very fast.
They have a long and rounded tail. The color is brown. River otters weigh 10 to 30 pounds. They are 3 to 4 feet long. Otters are active all year.