Reviving fish population requires more than clean creek

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Above photo shows weir that controls water flow on White Oak Creek and makes it difficult for fish to populate upper stretches. Photo below shows the weir removed. (ORNL photos)

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The capping of old nuclear burial sites to stem radioactive leaks and other cleanup measures have greatly improved the water quality in White Oak Creek, which meanders through the drainage basin of Oak Ridge National Laboratory.mcmanamaypic

In some ways, however, restoration of the creek has been a disappointment.

Despite its cleaner waters, White Oak Creek doesn’t have the diverse fish population that might be expected of an East Tennessee stream that has undergone such an extensive remediation.

Ryan McManamay, an aquatic ecologist at ORNL, headed a study — published recently in the scientific journal Hydrobiologia — that looked at the some of the issues.

At least partly to blame, maybe mostly to blame, are the many barriers that have been constructed along the creek to control the water flow and/or monitor its characteristics.
The series of dams, weirs and culverts — 32 barriers in all — have reportedly kept many species of fish from moving about freely and prevented them colonizing parts of the creek in a natural manner.

White Oak Creek has an unusual history, especially since the World War II Manhattan Project, when it was dammed up to prevent the lab’s radiological discharges from flowing directly into the Clinch River.

Construction of White Oak Dam created White Oak Lake, which became a giant settling pond for the radioactive gunk discharged by the lab and delivered by White Oak Creek.

Of course, the lab’s environmental practices changed dramatically over the decades, and multiple projects were undertaken to clean up the legacies. Caps were installed at the old burial grounds — euphemistically called “solid waste storage areas” — to keep rainfall from leaching the waste and carrying away the radioactive constituents.

ORNL scientists monitored the progress, and as creek conditions improved, they recognized that changes in the fish population hadn’t kept pace.

Around 2007, environmental researcher Mike Ryon led a team that stocked the creek with additional species in hopes of expanding that base. But there has been limited success in returning the creek’s population to what might be considered normal.

“The biggest issue is that the entire watershed is cut off from the Clinch,” McManamay said.
Besides White Oak Dam, there is a coffer dam even closer to the Clinch River that restricts fish traffic.

McManamay is now doing another study that evaluates possible strategies to remove some barriers and/or allow fish to navigate around them and make White Oak Creek their home.

Stay tuned.

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About Frank Munger

Senior Writer Frank Munger covers the Dept. of Energy's Oak Ridge facilities and many related topics — nuclear weapons, nuclear waste and other things nuclear, environmental cleanup and science of all sorts. Atomic City Underground is, first and foremost, a news blog, but there's room for analysis, opinion and random thoughts that have no place else to go.