The environmental cleanup of the Department of Energy’s Oak Ridge Reservation in Tennessee has taken place over more than three decades, with much of the progress measured by improved water quality in a series of creeks and waterways – including White Oak Creek, which is the main drainage system for the Oak Ridge National Laboratory.
Great effort has been expended and many millions of dollars spent trying to reduce the radioactive and hazardous discharges into the creek, and that progress is reflected in the ongoing monitoring results.
However, White Oak Creek’s improvements haven’t necessarily translated into one of the key metrics – greater diversity and numbers of fish species. The creek doesn’t have the type of fish population that might be expected, especially after all the cleanup efforts. In fact, White Oak Creek compares poorly with East Fork Poplar Creek, which originates inside Y-12 and was heavily polluted with mercury during the Cold War development of hydrogen bombs.
The East Fork, while still suffering elevated mercury levels due to past contributions, has made great gains in the number and types of fish that inhabit the upper stretches of the creek that were once inhospitable and almost inhabitable.
Ryan McManamay, an aquatic ecologist at ORNL, headed a recent study that evaluated some of the problems at the White Oak Creek, and much of the blame is reportedly on the many barriers in the creek that prevent the free movement of fish. Some of those barriers – dams, weirs, and culverts – were put in place to help monitor the pollution problems and environmental improvements.
McManamay said there are 32 of those barriers in White Oak Creek, and they have prevented fish from colonizing parts of the creek.
Pollution of White Oak Creek dates to the World War II Manhattan Project. The creek was dammed to prevent the nuclear discharges from flowing directly into the Clinch River and downstream reservoirs in East Tennessee.
The construction of a dam – known as White Oak Dam – created White Oak Lake, which gathered the lab’s discharges (via White Oak Creek) and later became notorious as the nation’s most radioactively contaminated body of water.
The practices have changed over the decades, and greater efforts were made to clean up the pollution. Caps were installed at the site’s waste burial grounds in order to prevent or limit rainfall from leaching the underground radioactive waste and carrying away the constituents.
Scientists have monitored the cleanup progress, but it was obvious – even early on – that’s the native fish species were not returning to the creek. There were even efforts within the past decade to reintroduce some of those fish to White Oak Creek to help things along. Those efforts, however, had only limited success because of the limited mobility within the creek itself. Ironically, some of the environmental efforts to monitor the creek were actually creating a problem.
“The biggest issue is that the entire watershed is cut off from the Clinch,” McManamay said.
The scientist said he and others are doing another study that will look at possible strategies to remove some barriers and/or allow fish to navigate around them and make White Oak Creek their home.
The study will also weigh the potential gains and evaluate them against their costs.
