Path to Grand Lake clarity standard far from clear #ColoradoRiver

Grand Lake via Cornell University
Grand Lake via Cornell University

From the Sky-Hi Daily News (Hank Shell):

Keep Grand Lake Blue. If you’re a resident of Grand County, you’ve probably seen those words pasted proudly to someone’s bumper. To the uninitiated, it seems like an innocuous, if not benevolent, goal. But to some Grand Lake fisherman, the issue is far from clear…

…a recent study by Brett Johnson, a professor in CSU’s department of fish, wildlife and conservation biology.

The study found that “pumping from Shadow Mountain Reservoir has an “enriching effect that should be beneficial to Grand Lake’s fish populations.”[…]

In 2008, the Colorado Water Quality Control Commission set in motion a process to develop a clarity standard for Grand Lake.

Most of the solutions proposed so far would include bypassing Grand Lake, eliminating the influx of dirty, nutrient rich water from Shadow Mountain Reservoir.

In turn, Johnson postulates this could result in declines in sport fish growth and production.

During the Nov. 20 meeting, Katherine Morris, Grand County’s water quality specialist, raised some concerns with Johnson’s study, namely that the nutrient sources that Johnson identified were primarily cyanobacteria.

Cyanobacteria are less edible than phytoplankton, and when they die in large quantities, they can be toxic.

Johnson has conceded that pumping cyanobacteria into Grand Lake wouldn’t be a good idea, Morris said.

Cyanobacteria are currently the primary producers in both Grand Lake and Shadow Mountain Reservoir.

“If we weren’t pumping the wrong nutrient ratio into Grand Lake, that might not be a problem,” Morris said.

Grand County will be issuing a rebuttal to the study, Morris said.

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