Round Lake Park Beach is closed until Wednesday for preventive algae treatment

Round Lake Park Beach is closed until Wednesday, July 20, while the city does its annual treatment for algae, submerged plant growth and the tiny invertebrates that can cause an allergic reaction known as “swimmer’s itch.” 

Eden Prairie officials say the treatment aims to make the water clearer and more pleasant for swimming. The Round Lake splash pad and Riley Lake beach will remain open.

“This is more about the amount of vegetation and the type that makes it uncomfortable for people than it is with the condition of the water,” said Jay Lotthammer, the city’s parks and recreation director, on Monday.

“They’re not like the larger wasp,” he said, describing the kind of wasps that burrow into the sand there. “They’re pretty docile, and there is just one per burrow. It’s not like there is this big nest situation. By us working up the beach sand area a couple of different times, that helps get rid of them or drastically reduce them.”

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Lotthammer said the county’s Round Lake water quality tests have been steadily good this summer. Hennepin County Public Health Department samples waters from all public beaches throughout the summer to check for water-borne illnesses. Round Lake was last tested on July 11.

But, he noted, it’s typically later in the summer that the city has seen the lake’s water exceed state water standard levels. Heavy rain after a long, hot, dry stretch is the catalyst for a spike in fecal coliform bacteria numbers in those instances.

“Usually it’s a day or two that it could be closed again,” he said. “But we’ve had a really good run of water quality so far this year, and we’ll continue to monitor it.”

In the recent past, Lotthammer said a spike in fecal coliform in the lake is primarily due to a buildup of lawn fertilizer. 

“The theory of what happens is when we’ve had that long dry period things kind of accumulate upstream,” he said. “We get a big rain, a whole kind of wash-in happens and spikes it. We determine that it’s not safe. Usually, it takes a day or two and those are diluted out, washed out and we’re in good condition to swim.”

About 15 years ago, Canada geese were the lake’s main culprit of high fecal coliform numbers. 

“That would end up spiking the numbers and closing it down far more often but luckily that has been taken mostly out of the equation,” he said. “It doesn’t have the same impact that it used to.”

What made a difference with the geese at Round Lake?

Lottenhammer said there were several years when the geese were netted and removed from the area at a time when they couldn’t fly.

“Since geese usually return to where they were born, this has made a lasting impact,” he said. “The improvements at Round Lake Park have also made this a busier location which also helps discourage new geese from congregating.”

For more on beaches in Eden Prairie, visit the city’s website.