Recent news articles report high harmful algal blooms (HABs) at state park lakes. At Choctaw Lake, 2013 and 2014 were both bad blue-green algae years with microcystin peaking at 17.5 ppb in 2013. But our recent investment in a water quality management program seems to have paid off. Last year, our highest microcystin concentration was 3.4 ppm.
Our recent microcystin reading of 0.1 ppb in mid-June is very good news!
Because microcystin tests are done at a lab and are expensive, we weekly monitor several factors related to microcystin concentration and do a lab test when those factors indicate likely microcystin growth. This week’s monitoring shows that our lake water quality has improved even further since mid-June.
Harmful algal blooms (HABs) are an excessive growth of cyanobacteria that are capable of producing toxins harmful to human health. Ohio EPA guidelines call for two levels of warnings: “Recreational Health Advisory” with microcystin concentrations of 6-20 ppb, and “Recreational No Contact Advisory” with concentrations greater than 20 ppb. If a “Recreational Health Advisory” is issued, swimming and wading are not recommended for children, pregnant or nursing women, and those with certain medical conditions. With a “Recreational No Contact Advisory,” all are to avoid contact with the water.
During the past three years, we’ve implemented an aggressive program to combat our microcystin worries. We’ve treated the lake with copper sulfate when our weekly lake water monitoring results caused concern. We’ve dredged phosphorus enriched sediment. Also, we’ve eliminated geese and installed aerators.
Individual home owners have done their part too. They have used phosphorus free lawn fertilizer, harassed geese so that they seek other environments, refrained from feeding geese, and kept clippings out of the lake and drainage ditches to prevent additional nutrients making their way into our water. They have adhered to boating rules, both the no wake/idle speed only rule and ‘no plow’ rule, to minimize stirring of bottom sediments rich in phosphorus. On the lake front, they’ve made sure the shoreline is adequately protected to prevent erosion. Construction projects involving bare earth have controlled erosion as well.
Most importantly, there has been less phosphorus moving into the lake from the watershed. Farmers in our watershed have reduced phosphorus fertilizer use and have installed riparian zones, cover crops, and grass filter strips. Some watershed farmers have used financial support from our grant funds to help pay seed costs for cover crops and grass filter strips.
Thanks to those who contributed to our improved water quality. During the upcoming holiday weekend, all can enjoy a splash in our lake that’s pretty darn clean.