By Stan Bush

LARIMER COUNTY, Colo. (CBS4) – The prestine stretch of the Big Thompson River is a flyfisher’s dream. A rippling current home to rainbow and brown trout that has captivated anglers and cradled the species for generations.

READ MORE: Denver Police Search For Pregnant Woman Suspected In Robbery At Knifepoint

(credit: CBS)

It was a disaster after the disaster. On Sept. 9, 2013 torrential floods decimated communities along The Big Thompson River, wiping out major portion of Highway 34 through the river’s canyon.

(credit: CBS)

Fish in the river were surprisingly unaffected by the floods, but the reconstruction of the highway did kill fish at an alarming rate.

(credit: CBS)

“Some of that immediate work led to habitat degradation and the population declined,” said Jake Ruthven, an aquatic biologist with Colorado Parks & Wildlife. “The water didn’t do much, but the human influence did.”

Rebuilding the habitat along the Big Thompson has been the largest stream reconstruction in state history.

READ MORE: COVID Restrictions In Colorado: Custer County Commissioners Vote To Drop All Restrictions, Open Up 100%

(credit: CBS)

The river has been restocked with rainbow and brown trout. Now game managers are closely monitoring the population. To do so, Ruthven and his team are electrifying portions of the river using poles which are essentially oversized cattle prods.

The current in the water stuns the fish. They tense up and are swept into a net. Moments later, the fish are back to normal, completely unharmed. The goal: to bring out at least 80 percent of the fish on any given length of the river.

(credit: CBS)

“We’ve spent three weeks in the river every year for the last three or four years,” said Ruthven.

Ruthven says they are checking to see if the reconstructed river is sustaining the population. The fish get what is essentially a physical. They’re examined for mercury and whirling disease, an aquatic version of mad cow disease; to this point there have been no issues.

“It’s like a new river, and its cool to see how far it’s come.”

MORE NEWS: Berthoud Real Estate Agent Bret Lamperes Charged With Money Laundering

Stan Bush is a general assignment reporter at CBS4. His stories can be seen on CBS4 News at 10. Read his bio and follow him on Twitter @StanBushTV.