The key takeaways from the 2019 monitoring season are:
• Green Lake has fairly clear water, with moderate nutrient concentrations and high algal growth. • Average 2019 chlorophyll, nitrogen, and phosphorus concentrations were noticeable higher than values observed in 2018. These concentrations are also noticeably higher than values observed before the alum treatment that occurred in spring 2016. • Algal blooms in June-July and again in October-November resulted in Algal Toxin Warnings. Toxin testing found elevated microcystin concentrations above the Washington State Recreational Guideline of 6 µg/L.
Please see below for a link to the full 2019 Green Lake Monitoring Report.
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The average of these three TSI indicators during the growing season can be used to place lakes in one of three broad categories: <40 = oligotrophic (low productivity), 40 to 50 = mesotrophic (moderate productivity) >50 = eutrophic (highly productive).