Argo Raag, head of security firm G4S's southern region, said there is an exceptionally large amount of algae this year due to favorable weather conditions.  

"I have not weighed it in kilograms, but a couple of trailer loads have been removed from here," he told ERR's "Aktuaalne kaamera" evening news show.

"There has been no notification that it would be dangerous. It's just visually unattractive. But before the start of the season, when we cleaned the beach here, we went through all of the algae with rakes to make sure there wasn't any debris on the bottom that someone could step on and injure their foot," he said.

Lifeguards at Anne Canal first noticed the algae in mid-May.

Ingmar Ott, chief specialist in applied hydrobiology at the Estonian University of Life Sciences, said filamentous macroalgae compete with aquatic plants.

"This is a sandy area and larger aquatic plants can't grow here because people and birds trample them. The area is maintained specifically to keep it looking like a nice sandy beach. The plants can't establish themselves, so filamentous green algae appear instead," Ott explained.

The abundance of green algae indicates that there are a lot of nutrients in the water.

The canal's water level has also been low, and the water is clear all the way to the bottom. While algae generally grow on the bottom of a body of water, abundant light can cause them to rise to the surface. The algal mass should eventually sink back to the bottom on its own, though it may reappear at the surface later in the summer.

"People want to see beautiful, clear water, but nature can't keep it that way because people place too much pressure on the lake," the scientist said.

Ott said a proposal was made to the City of Tartu 10 years ago to help keep the body of water cleaner, but the city did not implement the idea.

"The simplest method, which is also very inexpensive, is biomanipulation. That means — and it may be hard to believe — that if you introduce predatory fish into the lake, the lake becomes cleaner," he said.

The Health Board told ERR that based on the most recent sample, the water quality in Anne Canal is good and the algae there pose no risk to human health.

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