(Harlan) Starting Monday, the public will see some storage tanks along the shore and a large barge at Prairie Rose State Park.
John Lorenzen, fisheries biologist with the Iowa Department of Natural Resources, says the DNR contracted with a company to apply Alum. Lorenzen says Alum binds with phosphorus and settles out into sediment, making it impossible for algae to take up the phosphorus.
Lorenzen says 50 percent of the phosphorus available in Prairie Rose each summer is from in-lake resuspension, so a large percentage of algae problems can be addressed within the lake.
Lorenzen says that during times of the year when all the lakes have oxygen, phosphorus binds to iron, making it unavailable. However, during the summer, when a thermocline establishes and there is no oxygen below approximately eight feet, that chemical bond breaks, releasing the phosphorus into the water column to be taken up by algae, which is one reason the algae blooms happen in the summer.
