Lake Norman is looking more colorful these days.
Bright green, deep red and milky blue algae is blooming in northern parts of the lake — but these bright colors don’t bring good news.
More than 80 algal blooms on Lake Norman have been reported since the beginning of June, according to the North Carolina Division of Water Resources. Fertilizer runoff and warm water are the two main drivers of this growth.
Some of the algae emit toxins that are dangerous to people and wildlife. These are called cyanobacteria.
“Often when we talk about the harmful algal blooms, or toxic algae, we're talking about the cyanobacteria,” said Dr. Sandra Clinton, a professor of geography and earth science at UNC Charlotte. “Some of these cyanobacteria make what we call cytotoxins. They can be harmful … when they're high in concentration.”
Dr. LeeAnna Chapman, an earth scientist at Davidson College, said even nontoxic algae disrupt the ecosystem.
“All algal blooms can result in eutrophication, which can cause the oxygen in the water to decrease as the algae uses up all that oxygen,” Chapman said. “That can cause fish kills.”
Eutrophication happens when bodies of water have high amounts of nutrients, often nitrogen and phosphorus, which leads to excessive algae growth. The algae also use dissolved oxygen in the water to grow.
“When you decrease the dissolved oxygen a little bit, you start decreasing the fish species that can live there,” Chapman said. “The more the DO goes down, the less and less species that can exist in that environment.”
One thing people can do to prevent these blooms, according to Chapman, is use less fertilizer. When it comes to swimming, avoid the colorful areas.
“If the water looks like green, or a blue-green, you don't want to go in that water,” Clinton said. “You don't want to let your pets in the water.”
Residents can report algae sightings to the NC Division of Water Resources.
