(Harlan) Crews are treating the East Arm of Prairie Rose Lake with Alum. John Lorenzen, Fisheries Biologist with the Iowa Department of Natural Resources, says the process started on April 11, with an expected completion date of April 14.
Lorenzen says Prairie Rose is a good candidate for Alum because the main source of phosphorus leading to the algae blooms was internal phosphorus already in the lake, rather than in other lakes, where the leading source was from watershed inputs.
Lorenzen says Alum, or Aluminum Sulfate, is a non-toxic substance used in everything from cooking to treating drinking water, and is commonly used to reduce phosphorus concentrations in lakes.
Lorenzen says the application will bind the Alum to the Phosphorus and remove it from the water column, making it unavailable to algae and resulting in clear water.
The DNR is also applying Alum treatments at Green Valley and Lake of Three Fires.
