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 impacted, but 0.4 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 was initially reported by a resident. Wildlife officials waited to confirm the kill “until data had been thoroughly analyzed.”
first reported the fish kill on 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 a statewide recovery from the September 2013 floods. Around three years ago, before the floods, the Big Thompson fishery funneled $4.3 million annually into the local economy.
“Restoring the recreational fishery and creating a new road-river interface with long-term resiliency and natural function remains a priority for multiple agencies, despite the latest setback,” the agency said in a news release said.
The County Road 43 project, which is slated for completion in summer 2016, has fed chemicals from concrete into the stream, increasing the acidity of the water. The release said wildlife officials are working to reduce the chance of another fish kill and to recover the losses to the fishery.
Katy Canada: 303-954-1043, kcanada@denverpost.com or @KatySusanna
