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Environmental Board <br /> January 31,2024 <br /> Page 2 <br /> Mr. Nelson, Environmental Coordinator,presented the staff report and introduced Matt <br /> Kocian, Lake and Stream Manager with Rice Creek Watershed District (RCWD). <br /> Mr. Kocian presented his report regarding the Centerville Water Quality Updates. <br /> The main cause of high phosphorus loading in Centerville Lake is due to internal <br /> sediment recycling, which fuels algae blooms. The most commonly used tool to mitigate <br /> internal phosphorus loading is called Aluminum Sulfate ("Alum"). Alum permanently <br /> binds phosphorus in the sediments. In an effort to address algae bloom issues in <br /> Centerville Lake, RCWD requested a financial contribution of approximately 3% of the <br /> total project budget from each local partner to match the Clean Water Fund grant that will <br /> be funding the aluminum sulfate treatments. <br /> Ms. Nelson asked what are the conditions in order to start treatment in the Spring of <br /> 2024. <br /> Mr. Kocian replied that they would have to complete grant paper work and getting <br /> approval, as well as lining up contractors to do the work, which typically takes time. <br /> Ms. Holmes asked if they can start in the Summer of 2024. <br /> Mr. Kocian replied no because alum is best to apply in the spring when the water is the <br /> clearest and has less algae and nutrients in order for the alum to reach the bottom of the <br /> lake as quickly as possible. Mr. Kocian added that alum would only be applied to areas of <br /> the lake that are 10 feet or deeper where there is less oxygen. Additionally, as alum <br /> settles to the bottom of the lake, it is not a barrier and does not inhibit plant <br /> growth. <br /> Mr. Schwartz asked if there are more permanent solutions available, as opposed to <br /> expensive alum treatments every 15-20 years. Mr. Kocian responded that there are other <br /> seemingly permanent solutions to sediment phosphorus such as dredging or pumping <br /> high phosphorus water out of the bottom of the lake, but the cost of those tools are many <br /> times more expensive then alum in the long run. <br /> Chair Sullivan accepted to take public comments from those who came after open mic. <br /> Christopher Stowe, 426 Pine St, expressed concerns regarding exotic plants that may <br /> arise when phosphates are removed and allow for plant growth, such as Eurasian <br /> Watermilfoil. He also expressed concerns regarding taxpayers potentially contributing to <br /> several of the partner contributions,paying to RCWD and the City they live in. <br /> Catherine Decker, 614 Pine St, expressed concerns about the statement that a majority of <br /> the funding would pay for the alum treatment, noting that this would leave 49% of the <br /> DRAFT MINUTES <br />