Stocking a river with one of the nation’s rarest fish is a slow and gentle process.

On a recent summer day, biologist Steve Fraley lowered a clear-plastic bag full of water and 50 small, threatened fish called spotfin chub, into Graham County’s Cheoah River, holding it closed until the water temperature in the bag approached that of the river’s. After a few minutes, he opened the bag and slowly mixed in river water before finally giving the fish free rein to enter the river. By the end of the day, 844 of the tiny fish were released following the painstaking acclimation process.

“To watch us empty those bags in the river may seem a little anti-climatic, but returning this rare fish to this river is a tremendous step in restoring the river’s rich diversity and one that is the result of a lot of effort by a lot of people,” said Fraley, a biologist with the North Carolina Wildlife Resources Commission who has directed the effort to restore the spotfin chub in the Cheoah.

This is the second year in a row the North Carolina Wildlife Resources Commission has stocked the rare minnow in the Cheoah, and the latest chapter in an effort to bring back the river’s biodiversity. For decades the nine-mile river reach between Lake Santeetlah and its confluence with the Little Tennessee River was largely dewatered by Alcoa Power, which diverted the river to a hydropower generator.

Some fish and other aquatic life, including a remnant population of endangered Appalachian elktoe mussels, were able to hold on in the Cheoah River thanks to a trickle of water seeping through the dam and small feeder creeks.

A few years ago, however, federal environmental regulations forced Alcoa to stop diverting the entire river and return a small flow of water to the natural riverbed.

The spotfin chub, a fish on the federal endangered species list, is the latest in a series of reintroductions aimed at restoring aquatic life to this stretch of river. Wavy-rayed lampmussels and the wounded darter, a small, bottom-dwelling fish, are also being reintroduced. Other native species on the horizon for stocking in the Cheoah include the rainbow and Appalachian elktoe mussels.

The effort is being led by U.S. Fish & Wildlife Service and the N.C. Wildlife Commission.