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CENTERVILLE LAKE ALUM TREATMENT FREQUENTLY ASKED <br />QUESTIONS <br />ALUM TREATMENT <br />What is Alum? <br />Aluminum sulfate (“alum”) is one of the most widely used substances in water and wastewater treatments (USA EPA). <br />It’s often used to address issues related to excessive nutrient levels, particularly phosphorus, and has been used in <br />lakes across the United States and Europe to improve water quality for decades. <br />How does Alum work? <br />When applied to water, alum forms a “fluffy” aluminum hydroxide material called “floc”. As the floc settles, it removes <br />phosphorus and particulates (including algae) from the water column by binding to it. The floc settles on the sediment <br />(aka lake bottom) where it forms a layer that acts as a barrier to phosphorus. Phosphorus that would release from the <br />sediments on the lake bottom, is “locked” in place by the alum and can’t go back into the water to fuel algae blooms. <br />Why are we doing this Alum treatment? <br />Alum reduces phosphorus, which is a significant contributor to the lake's poor water quality and harmful algae blooms <br />(see photo below). Algae blooms like this can produce toxins that are dangerous to animals and people. Alum will <br />improve water clarity and create a healthier lake. Alum is cost-effective and has a proven track record in restoring water <br />quality in lakes facing similar challenges. <br />How long will the application take? About a week and a half <br />When will the treatment begin? Either early spring or late fall <br />What will the lake look like during treatment? Milky-white <br />but changing to clear water very quickly. <br />How long will the effects last? Since Centerville Lake <br />doesn’t receive much phosphorous from outside the lake, this <br />treatment is expected to last about 20 years. <br />Does an alum treatment fix all water quality issues? <br />While an alum treatment can significantly improve water clarity/quality by <br />reducing phosphorus levels, it may not address all issues. Continuous <br />monitoring and long-term management strategies such as water quality <br />monitoring, restoring shorelines with native plant communities, controlling <br />invasive species, and installing other stormwater management practices <br />around the lake are needed to protect and keep the water quality good. <br />What happens after the alum treatment? <br /> You’ll see an improvement in water clarity right after and into the following <br />months. This improved clarity WILL support the regrowth of native aquatic <br />plants. These plants are essential to providing habitat for aquatic life and <br />to further improve water quality. A decrease in phosphorus will also help <br />control algae blooms in the future. <br />Figure 1 Harmful Blue Green Algae Bloom on Centerville Lake <br />Figure 2 Example of the n ative aquatic p lant <br />c ommunities that will regrow on Centerville <br />Lake <br />5