WAYNESBORO, Va. (WVIR) - The sweltering heat over central Virginia and the Shenandoah Valley is taking its toll on the region's waterways.

Long stretches of high temperatures can threaten the survival of some freshwater fish.

Meanwhile, trout and other coldwater fish want to find shady spots to rest and cool off when temperatures soar.

Outside temperatures of around 100 degrees means water temperatures in stretches of the South River can heat up around 70 to 80 degrees. Those temperatures send trout searching for cooler water in the shade along the river bank, or down into deep pools.

The South River in Waynesboro has several cold springs where the water temperature is always around 55 degrees. Shenandoah Valley Trout Unlimited President Jim Josefson says those springs help fish survive through a heat wave.

“Trout are a special kind of fish. They're not like bass, they can't live in warm water. They have to be in water that doesn't get much above 70 degrees. So hot weather like this is going to stress them,” he said.

Josefson's group is working to help boost the trout population by digging deeper pools along the river where the fish can hang out in hotter weather.

“With those strategies, as long as it doesn't get too hot for too long a period of time, the trout will be OK,” Josefson said.

Keeping trees for shade along the river and improving water quality can also help coldwater fish survive, but Josefson worries about the threat posed by climate change.

“Some models Trout Unlimited has looked at suggest there might not be Brook Trout in Virginia, our state fish, in 100 years,” he said.

Josefson says improvements to the flow of the South River over the past few years allow water temperatures to cool down at night from their daytime highs.

For fly-fishers, the recent summer heat means the best time to catch coldwater fish is during the early morning or late evening when the water temp is cooler.