Dr. Nate Bosch, Center for Lakes & Streams at Grace College executive director, gave a presensation on a study of 19 of Kosciusko County’s largest lakes titled “Beneath the Surface: An Investigation Into Your Lake’s Health” during Monday night’s Warsaw City Council meeting. These reports are a culmination of the center’s four-year study of blue-green algae toxins and addressed factors affecting local lakes including algae growth and toxins, E coli levels and dissolved oxygen. These reports were distributed in May to residents living on lakefront properties and are available at lakes.grace.edu Observations were that Winona Lake’s water clarity was typically worse in the middle of the summer. This decreased clarity is partially caused by phosphorus and nitrogen making more algae grow in the middle of the summer. Algae populations in Winona Lake were often well above blue-green algae guidelines for human health even though microcytic toxin levels were consistently low. It appears that the algae populations in Winona Lake are either producing less toxin than other county lakes, or they are producing different toxins that were not tested for in this study. Even though Winona Lake’s algae populations measured well above blue-green algae guidelines for human health, its microcytic toxin levels were consistently low. In the open areas of Winona Lake, E coli levels were well beneath the health guidelines though this study did not include extensive sampling of various shoreline areas where E coli levels are often higher. Both phosphorus and nitrogen levels in Winona Lake were consistently well above the Environmental Protection Agency recommended guidelines. When Winona Lake’s oxygen layer gets thinner through the summer, fish get squeezed into a warmer and smaller area. The resulting lack of oxygen makes it difficult for these fish and their food sources to survive. This lack of oxygen is caused by too many nutrients in the lake. For Center Lake, the study states water clarity could be better. Decreased water clarity can be caused by nutrients making more algae grow during the summer. Even though Center Lake’s microcytic toxin levels were consistently below guidelines for human health, the high variability of these levels indicates strong potential for future risk. Under the right conditions, such as high nutrient levels and warm temperatures, blue green algae could produce microcytic toxin levels above human health guidelines in Center Lake. The elevated E coli levels in this shoreline area of Center Lake are likely due to waterfowl, pier characteristics and stormwater influences. High oxygen levels in Center Lake during the summer indicate high algae and plant growth from too many nutrients in the lake. Bosch also reminded the council the Northern Indiana Lakes Festival starts Friday from 5 to 9 p.m. and goes until June 20. Events can be found at lakes.grace.edu
