Tag: trout

Thousands of fish die in Colorado, amid flood recovery projects

Thousands of fish die in Colorado, amid flood recovery projects

Cars drive on County Road 43, in Larimer County, Colorado, past a road reconstruction project after the 2013 floods. Some bridge-building may have contributed to a fish die-off (Photo via Larimer Country Road 43 Public Infrastructure Project)

In March 2016, a resident of the small Colorado towns of Drake and Glen Haven — situated within northern Colorado’s Big Thompson River Canyon — reported noticing funky gray water in a side creek of the river and a murder of crows picking at a few dead fish. A few days later, March 7, a large plume of more cloudy water ran down the Big Thompson, leaving behind a massive fish kill. Colorado Parks and Wildlife officials now confirm that more than 5,600 fish, mostly rainbow and brown trout, died in the Big Thompson and its North Fork, and are blaming concrete from a bridge reconstruction project, part of the state’s massive recovery and reconstruction effort following the devastating September 2013 floods.

The die-off is alarming news for the Big Thompson, a popular fly fishing river among tourists and locals, which formerly generated an annual $4.3 million for the region. Larry Rogstad, Colorado Parks and Wildlife Area Manager, says the “iconic” fishery is also important as one of the only rivers in Colorado with wild rainbow trout free of whirling disease. The 2013 floods had already knocked back the river’s fish populations, and Rogstad estimates the recent incident killed more than half of the estimated fish within an eight-mile-long downstream stretch of river.

Jeff Crane, a consulting river hydrologist and restoration expert, says he’s surprised at the magnitude of the fish kill. But he adds that it’s also important to recognize the complexity and ambition behind recovery projects aiming to improve rivers’ natural functions and flood resiliency.

For instance, the previously straightened river now bends and courses through the middle of the canyon, while several new bridges are replacing buried culverts that typically get blocked or exceed capacity during flooding. “We’re actually ‘building’ a whole new river,” says Crane, a proponent of “natural channel design” that mimics natural landforms and uses less grouted rock, or riprap, than conventional flood-protection measures. Despite the fish kill, the local restoration should improve fish and aquatic habitat and reduce flooding damage in the long run, Crane says.

“Thousands of fish die in Colorado, amid flood recovery projects”

High Country News, April 26, 2016

AllEscort