An algae bloom killed fish in a popular eastern N.C. swimming and fishing lake, not the chemical used to treat the outbreak, state officials concluded after studying the brains of some of the dead fish.
The bloom caused high pH levels that led to the deaths in White Lake in early May, state officials wrote to officials in the lake's namesake town. Officials also took and reviewed water samples before concluding that the bloom was the culprit.
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Algae blooms occur when nutrient levels in a body of water are too high, White Lake officials said in a statement on the town's website this week. The blooms often cause a "significant drop" in dissolved oxygen levels, and that is what can kill fish of all kinds, the statement said. Such blooms occur as the weather warms, according to the statement.
Scores of fish died in the lake after the town began using a state-approved, low-dose aluminum sulfate treatment to lower the lake's pH levels and improve water clarity, Wilmington NBC-TV affiliate WECT reported. The algae had discolored the water.
People like to catch bass, perch and pickerel in the lake, according to Carolina Sportsman magazine.
The town stopped the 10-day treatment after residents found the dead fish. The town completed the treatment after the state studied the matter and found that the water is safe for public use, according to the town's statement.
The findings came ahead of the town's 40th annual White Lake Water Festival on Friday and Saturday .
White Lake is a 1,200-acre spring- and rain-fed lake that lacks shoreline vegetation and other measures to protect it from nutrient runoff, according to the statement. But five years of testing and studies have failed to reveal what's causing the high pH levels, the White Lake statement said.
White Lake "is also continuing its partnerships with scientists and environmental leaders to find both short- and long-term solutions to the situation," according to the statement. The town is working with the Bald Head Island Conservancy to understand the causes of the blooms.