Wildlife News

Green River research on flow changes

Researchers will present findings on May 4

DUTCH JOHN — Six years ago, a controversial water policy was adopted for one of the best trout fishing waters in the country — the Green River below Flaming Gorge Reservoir in northeastern Utah.

A large rainbow trout from a recent Green River survey.

This healthy rainbow trout was part of a recent sampling on the Green River.

Photo courtesy of Ryan Mosley

The policy changed when water was released from Flaming Gorge Dam in the winter. Instead of releasing water at a continuous rate, flows were ramped up in the morning and the evening — when the need for electricity was the greatest — but were cut back during the rest of the day and night.

These "double flows" created concern. Would the unnatural flow pattern upset a multimillion dollar fishery? Would it hurt the river's sport fish? Would it change their habitat and affect the macro-invertebrate populations (aquatic insects and other species) the trout prey on?

For the past six years, researchers from Argonne National Labs and the National Aquatic Monitoring Lab at Utah State University (affectionately known as the USU "Bug Lab") have studied how the trout fishery and macro-invertebrates have responded to the changed winter flows.

You're invited to hear the researchers present their findings on May 4, from 6 to 8 p.m., at the Dutch John Community Center.

May 4 presentation

Trina Hedrick, regional aquatics manager for the Utah Division of Wildlife Resources (UDWR), says the study was completed last winter. Now, the researchers are ready to present their findings. "We've had updates, more like teasers, over the last few years," Hedrick says. "I'm interested to hear the final results."

Using data collected by UDWR biologists during spring and fall electrofishing surveys on the river, and other information collected during the study period, Argonne has put a model together that helps predict how changes in the river flow affect the fishery.

Models such as these are never perfect," Hedrick says, "but with enough information, the model can help us understand how the fishery will respond to certain changes in the river. The model can also help us understand how sensitive the fishery is to different degrees of change."

Scott Miller and his crew from the "Bug Lab" will also present their research on the macro-invertebrate (i.e. "bug") assemblage — how it's changed over the years and what the biggest initiators of change have been.

Hedrick says most of the May 4 meeting will involve the researchers presenting their findings. "There should also be an opportunity to ask questions and maybe time for a brief discussion about future operations at Flaming Gorge Dam," she says. "If you'd like to learn more about this project, please attend the presentation."

For more information, call the UDWR's Northeastern Region office at 435-781-9453.

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