Monitoring Nutrient Levels and Sediment in Lake Macatawa Watershed
Dr. Aaron Best, Biology, Dr. Brent Krueger, Chemistry; Dr. Mike Pikaart, Chemistry; Sarah Brokus; Chelsea Payne; Randy Wade
Project Clarity, a $12M restoration project initiated in 2013, works to restore the 179 mi2 hypereutrophic Lake Macatawa Watershed. Our goal is to assess Project Clarity’s impact on water quality by collecting weekly samples from 12 representative sites. Physical and chemical parameters including total suspended solids, nutrients (phosphate and nitrate), temperature, stream discharge, dissolved oxygen, and biological oxygen demand are measured and correlated to the composition of the watershed’s microbiome. The watershed’s physical and chemical parameters vary. For example, during large rain events there are rapid surges in stream height and discharge. Project Clarity implements best management practices for land use in an attempt to minimize the impacts of rain events large enough to produce heavy runoff. Runoff often carries large amounts of fine grained sediment that has the tendency to adsorb nutrients. Most of these sediments end up entering nearby waterways, causing a decrease in water quality. Excess suspended solids strain aquatic populations by increasing temperature and decreasing dissolved oxygen and clarity. Measuring sediment as total suspended solids allows for approximation of sediment loading and transport. TSS levels in the fall of 2016 averaged around 15 mg/L, with maximums as high as 125 mg/L at a stream site during a rain event. The MDEQ found the average phosphorus concentration in Lake Macatawa was 0.125 mg/L Phosphorus in 1997, and set the goal total maximum daily load (TMDL) to reach 0.050 mg/L P by 2009. To date, this TMDL has not been consistently met. Phosphorus levels in Lake Macatawa averaged 0.065 mg/L during our fall 2016 monitoring. Additionally, nitrate levels are somewhat elevated. These data provide a baseline of water quality characteristics for monitoring remediation efforts in the watershed. Correlations between data are explored for potential influence on large-scale biogeochemical cycling.
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