Strong storm may have triggered fish kill
A strong thunderstorm early last Saturday morning may have been the trigger for the largest fish kill on High Rock Lake in at least 20 years. Thousands of dead fish litter the water and shores of a cove on the southwestern side of the lake. A wildlife officer confirmed the situation Saturday morning, but staff from the State Division of Water Quality didn't come to assess the damage or declare a cause of the fish kill until Tuesday. At that time, they said the fish suffocated for lack of oxygen in the water and that it was weather-related. However, environmental activist Dean Naujoks of the Yadkin Riverkeeper is skeptical, pointing instead to a major sewage spill in August. "When you introduce 15 million gallons of raw sewage into a struggling water body, we said several weeks ago that you were likely to see algae blooms and fish kills much later down the road," says Naujoks. But officials with the Division of Water Quality say that sewage is unlikely to have traveled several miles down the lake and through a culvert to reach the cove. When they tested the water on Tuesday they found nothing out of the ordinary, despite shores piled with dead fish ranging from a few ounces to several pounds. Locals are skeptical of the weather explanation, too. But the National Weather Service did report a strong thunderstorm with winds gusting up to 50 miles per hour around 10 a.m. on Saturday. The cove was in its path, and UNC Chapel Hill marine scientist Hans Paerl says that kind of weather can cause fish to die. "Here's the scenario to a low oxygen kind of fish kill," explains Paerl. "The system has been stagnant all summer. There's plenty of algae growing in the system. Over time, the bottom water runs out of oxygen and the fish can be perfectly happy as long as the water is not disturbed." But if a storm or sudden change in wind comes along at just the right time, "that bottom water can slosh up against the side and then come to the surface, covering the entire water column with low oxygen water," says Paerl. "The fish basically don't have any way to escape that." The storm may have been the trigger for the fish kill, but pollution is what set up the conditions to begin with. High Rock Lake has been on the state's list of impaired water bodies since 2004. More than a hundred waste water treatment plants feed into the lake, along with stormwater and agricultural run-off. Algae thrives on that pollution, robbing the water of oxygen and putting fish at risk. Even still, this latest fish kill is the first on High Rock Lake since 2002, when drought conditions depleted the oxygen in the water. Watch Yadkin Riverkeeper video of the dead fish.