5,600 fish killed by runo≠

Chemical runoff from a construction site produced a massive fish kill March 7 on the Lower North Fork Big Thompson and Big Thompson River from Drake to west Loveland, according to Colorado Parks and Wildlife.

In a statement posted on its website, the agency said more than 5,600 fish — including rainbow and brown trout, suckers and dace — died and blamed the incident on the Storm Mountain Road Bridge reconstruction project along Larimer County Road 43. Details of the event are still under investigation.

Colorado Parks and Wildlife officials estimated that the area impacted by the kill extends 8.3 miles downstream from Loveland’s water treatment facility. The release said portions of the Big Thompson River between Drake and Estes Park weren’t affected, but fourtenths of a mile of the North Fork likely suffered a complete loss. The main stem of Big Thompson from Drake to the Loveland water treatment facility suffered a 52 percent loss.

The incident initially was reported by a resident. Wildlife officials waited to confirm the kill “until data had been thoroughly analyzed.”

High Country News first reported the fish kill Tuesday. The High Country News account of the fish kill noted that construction initially sent a plume of cloudy water down the Big Thompson.

The construction project that caused the die-off is part of the statewide recovery from the September 2013 floods.