Planktonic algae, the cause of Lake Altoona’s green tint, contain toxins that are a concern for children and pets, but there are no serious health issues for adults using good judgement. The other algae growing on the lake this past year, filamentous algae, do not contain toxins.
According to Department of Natural Resources Watershed Supervisor Paul LaLiberte and the Eau Claire City-County Health Department, when the blue-green form of planktonic algae “bloom”, they emit toxins that can be hazardous to pets and children. LaLiberte says this bloom usually occurs during mid-to-late summer, when planktonic algae are the greenest. There have been no cases of illness in Altoona.
LaLiberte said the planktonic algae are located in Lake Altoona water columns, and “is very common in flowages where we have a lot of human activity upstream.”
“We encourage people not to swim near those areas,” said Eau Claire City-County Health Department Director Richard Thoune.
According to the Wisconsin DNR website, contact with an algal bloom can cause skin rash, hives, runny nose, irritated eyes and throat irritation. If it’s ingested, could cause vomiting, diarrhea, headache and, in severe cases, death.
Thoune also said the department tries to keep the public informed about blue-green algae and noted it usually is not located near swimming areas.
LaLiberte said planktonic algae have caused the green tint in Lake Altoona and local river flowages for decades. The amount and variety of algae changes from year to year; this summer, filamentous algae have also been present. The filamentous algae usually grow on the water’s surface near shore and can break off in sheets when the wind picks up.
LaLiberte said both planktonic and filamentous algae are conducive to areas with high levels of phosphorous, caused by a low flushing rate from the lake. Phosphorous is commonly found in Lake Altoona, but when the flow from the Eau Claire River is slow, the algae are more apt to grow.
“It seems to be a good year for growing both kinds of algae,” said LaLiberte.
According to LaLiberte, the algae growth is dependent on the climate and the algae normally begin to die off in August and September when the temperature drops.
Minutes posted online from a November 13, 2006 meeting of the Lake Altoona Rehabilitation and Protection District Board of Directors note blue-green algae concerns being taken off the table. No minutes prior to that date were posted, and successive posts had no mention of the issue. Lisa Schuetz, chairperson of the LARP, could not be reached for comment.
The algae in Lake Altoona do not call for a beach closing. Thoune said the beach closings are due to bacteria levels in the lake, which is tested weekly by the health department when beaches are open. If bacteria exceed 200 fecal coliform units per 100 milliliters of water, they issue a beach closing order to county park officials.
After a hard rain, fecal coliform from geese, ducks, seagulls, and occasionally street runoff drains into the water systems.
However, street runoff has become less likely because of modern construction engineering.
“We have a lot more attention to managing storm water (now), to the way we did things 20 years ago,” said LaLiberte.
Erosion problems can occur from freeway runoff, but according to DNR Water Resources Engineer Judy Hayducsko, construction areas have been able to handle any water runoff from a construction site, and she has not heard any complaints about major construction areas.
For any concerns regarding water runoff from construction sites, Hayducsko said she “would be happy to handle any complaints.” Information on blue-green algae can be found on the Wisconsin DNR website.