When algae blooms decompose they reduce the amount of oxygen in the water, which can kill fish. (Photo: DEQ)
Recipe for an algal bloom:
- Heat a shallow bowl of lakes, creeks and sounds to summer temperatures, at least 80 degrees
- Add 14 hours of sunlight, daily
- Combine with copious amounts of wastewater, fertilizer runoff
- Let stand for two to three months
- Optional: Stir in fish
The NC Department of Environmental Quality has received dozens of reports of algal blooms and fish kills this summer, according to the agency’s online dashboard. In just the first two days of August, the public reported four algal blooms and five fish kills. Last month, DEQ received reports of 51 algal blooms and 10 fish kills.
“A large decaying red mass in the water,” three-quarters of an acre in size, near Corolla.
“At least 100 catfish, floating dead,” in Jordan Lake on the north side of the U.S. 64 bridge, in Chatham County.
“Dozens of dead fish, mostly catfish and striped bass, along with dozens of floating (dead) crabs and dozens of floating clams,” among the brownish pods of algal blooms, south side of Albemarle Sound, near Roper.
Map: DEQ
Algae are aquatic organisms that thrive in warm, sun-lit, slow-moving water. When fed by nutrients, such as fertilizer from golf course runoff or wastewater, algae form blooms, a nice word for scum. When the blooms decompose, the amount of oxygen in the water declines, suffocating the fish.
Some forms of blue-green algae produce bacteria that are toxic to people and animals. (An EPA scientist once called this algae a “seven-stepper,” because after an animal drinks the contaminated water, they take seven steps and die.) It’s difficult to know whether algae is toxic merely by looking at it — the bacteria is microscopic — so avoid any water with a scum.
Consistently warmer temperatures and extended summer weather, both a result of climate change, create optimal conditions for algae to multiply. In the last 12 months, there have been at 136 algal blooms and 52 fish kills, according to DEQ. In all of 2021, the public reported 90 algal blooms and 44 fish kills. (This was still during the pandemic, so fewer people could have been out and about to witness the blooms and kills.)
If you see an algal bloom or a fish kill, report it to DEQ via this website. You can also upload photos.
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