BEDFORD - The Iowa Department of Natural Resources (DNR) will host a public meeting on March 4, at 6 p.m. at the Bedford Community School, to discuss an upcoming alum treatment to improve water quality at Lake of Three Fires, in Taylor County.
The Iowa DNR will present an overview of the proposed treatments and how this treatment will help reduce the frequency and intensity of harmful algae blooms (or HABs) in the lake.
Alum (aluminum sulfate) is a nontoxic substance used in everything from cooking to treatment of drinking water, and is commonly used to reduce phosphorus concentrations in lakes. Phosphorus is a key nutrient for algae growth, and stems from runoff in the watershed. While much of the phosphorus that ends up in a lake is buried in the lake sediments, under the right environmental conditions, phosphorus can also be recycled within the lake, being released from the lake sediments when bottom waters have no oxygen.
These “internal releases” of phosphorus often fuel large algae blooms, especially in the late summer and early fall. When applied to a lake, alum binds with the phosphorus in the water and settles as a thin flocculant on the lake bottom, where it will continue to inactivate phosphorus being released from the sediments. This process can significantly reduce the likelihood of HABs, which can be harmful to the ecosystem and limit recreation.
Lake of Three Fires has experienced several significant HABs over the past few years and generally has poor water clarity. Several research efforts have shown that watershed inputs and internal phosphorus recycling are driving these blooms, and that a series of alum applications will likely help alleviate the frequency and duration of HABs.
The alum will be applied using specialized barges over a period of two weeks, depending on weather conditions, between April 1 and May 15. During this time, lake users may see boats, barges, heavy trucking equipment, and storage tanks around the park that are being utilized to complete the application. There should be minimal disruption to regular activities on the water and the application window was selected to minimize interference with spring fishing activities. DNR asks that you maintain a safe distance from the equipment to allow the crews to work efficiently and will have staff on hand to monitor the application. No swimming or boating restrictions are anticipated.
This treatment is one part of a broader effort to continue to improve water quality and recreational opportunities at Lake of Three Fires. An additional treatment is slated for this fall.