Algae blooms appearing after heavy rains

Algae blooms appearing after heavy rains

Heavy rains that brought flooding in recent weeks left behind the perfect conditions for algae blooms that have been popping up in coves all around the lake.

Algae blooms are a rapid increase in the population of algae in water systems. They cover the water and can be dangerous to wildlife, pets and people. Recent rains washed extra nutrients into the lake. When the water warmed, the algae bloomed.

“We live in an area where we are surrounded by farms that either grow things or raise things,” said Mike McCord, director of the water quality monitoring progam for the Smith Mountain Lake Association. “Growing things requires a lot of fertilizer and raising things means there are a bunch of animals that do their own processing of the plants and that provides other nutrients into the soil that when it rains as hard as it did it runs off into the lake.”

Bob Pohlad, Ferrum College professor and senior scientist for the water quality monitoring program, said the excess nutrients of nitrogen and phosphorus is what allows the algae to grow. Those nutrients give algae a boost when they reach the water, he said.

Algae is nothing new at the lake. McCord said there are algae at the lake all the time. Algae comes in three types: diatoms, green algae and blue-green algae, he said.

“Only one of them is of concern and that’s the blue-green algae,” McCord said. “And that is only because there are some types of blue-green algae are capable of producing toxins. Those toxins can be harmful to animals and humans.”

Recent samples of blue-green algae were taken near Contentment Island near channel marker B13. They were tested by Pohlad and found to be capable of producing toxins in concentrations higher than what is normally found at Smith Mountain Lake.

Last year only 12% of the algae found in SML were blue-green algae and there were only small amounts of the strains capable of producing toxins, McCord said. While potentially harmful, the algae blooms on the lake disappear quickly.

“The lake fixes itself because water flows into the lake from the Roanoke and Blackwater rivers and it’s pulled down stream by the dam,” McCord said. “Only in coves where the water doesn’t move does the algae stay longer.”

No one should swim where there is algae on the lake. Animals should also be prevented from swimming or drinking the water where there is algae. It can cause skin irritation or nausea.

“A lot of the algae you need, because they are a part of the food chain,” Pohlad said. “They are not all bad. They are fed on by invertebrate animals, and those animals are fed on by fish and that keeps the whole ecosystem going.”

Pohlad and his team are working on an app that allows people to take a picture of algae and report its location to the lab and SMLA. This will allow them the track the blooms and excess nutrients that cause them. Pohlad said this is probably the largest number of algae they have seen on the lake.

“I am hoping this is an anomaly and we won’t have this kind of heavy rains, but as you can tell, we are getting a lot of climate change situations where we are getting a lot of heavier rains and slower moving storms that are holding rain over us for longer periods of time,” Pohlad said.

To report algae blooms, call the Smith Mountain Lake Water Quality Project lab at 365-4612 or visit

SML water quality issues can also be reported to the SMLA at or by contacting Mike McCord at or 488-2646.

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