It doesn't happen often but last month state officials had to ban swimming and recreation on Pelican Lake in Watertown because of toxic levels of algae.
The lake is now back open - and while the closure is uncommon - officials say algae in South Dakota lakes is not.
"We've been swimming in it for two days now and we don't have any problems. It's great," Jody Peterson said.
Peterson watched as her kids and their friends swam in Pelican Lake this week after they were turned away from the state recreation area following a toxic algae bloom last month.
"With kids and pets we'd rather have the state be over cautious than under, so yes we're very appreciative they kept us out for the time they did," Peterson said.
In the middle of June the water on the lake was green. Andy Kopp an environmental scientist with the Department of Environment and Natural Resources found a severe algae bloom happening below the surface.
Previous Story: Algae Blooming In Pelican Lake
"We were getting complaints from lake residents concerned that there were dying songbirds and dying squirrels happening on the north side," Kopp said.
The beach was closed at the Pelican Lake Recreation Area for twelve days, but now Kopp and state officials say the lake is safe again.
"They tend to come on really strong, really fast and then they tend to die down and algae toxins tend to degrade pretty fast in the water as well," Kopp said.
"The water recreation was definitely affected we're just starting to get that back now. You can hear the swimmers in the background which is great," South Dakota Game, Fish and Parks District Supervisor Jay DeLange said.
Several lakes in South Dakota are prone to algae blooms in the summer; however, many don't reach the level found on Pelican Lake. A water quality report from the South Dakota DENR this spring says many lakes in the eastern part of the state have these blooms because the lakes are shallow and because fertilizer and waste runs off from nearby farms, lawns, and livestock operations.
"Warm and calm weather coupled with high nutrient levels already in the lake generate conditions that are conclusive to algae blooms," Kopp said.
"The potential of a situation like this can occur on any natural lake in northeastern South Dakota here so when it does occur we want to maintain a safe attitude and make sure safety is our prime concern," DeLange said.
That's why officials keep a close eye on the lakes to make sure the regular blooms aren't reaching dangerous levels. The state monitors the water quality on lakes throughout South Dakota on a regular basis. They have a lake assessment program and take random samples from random lakes every single year.
"With those lakes we test for bacteria levels, nutrient levels, water clarity, pH, dissolved oxygen and chlorophyll levels, so we try to gauge the overall health of lakes across the state with this program," Kopp said.
Kopp says homeowners who live near lakes can help out by not spreading too much fertilizer on lawns and by cleaning up pet waste.
Peterson is glad that the bloom didn't last long and that Pelican Lake has now cleared up so her kids can enjoy their favorite summer swimming spot again.
"We were happy that they kept us out when they had some issues. We're glad it's open now and yes we feel 100 percent comfortable bringing our kids here and spending time here," Peterson said.
Spending time on a beach where warning signs have been replaced by summertime screams.