FORT COLLINS, Colo. (CBS4) – Colorado Parks and Wildlife is trying to solve a mystery in the Cache la Poudre River. A large number of fish have died off west of Fort Collins.

(credit: Colorado Parks and Wildlife)

The department tweeted that workers are sampling water. They are focused on a stretch of river from Linden Street to Timberline Road.

They hope to narrow down the area where fish are dying so they figure out what’s causing it.