LEA visits Crystal Lake twice a month in May through September. This year’s average total phosphorus concentration was near the long-term average, while the average clarity reading was more shallow than the long-term average and the average chlorophyll concentration was above the long-term average. The average deep-water phosphorus value was less than 10 ppb above surface water phosphorus values, which suggests phosphorus recycling was not problematic. Long-term trend analysis indicates chlorophyll-a concentrations and clarity readings are decreasing, while total phosphorus concentrations in Crystal Lake are stable. This year’s average surface water temperature was higher than last year’s average surface water temperature. Oxygen depletion was observed at the deepest parts of the pond in September. Gloeotrichia echenulata colonies were observed in Crystal Lake beginning in late July with densities ranging from less than 0.5 – 2 on the Gloeo density scale.
Crystal Lake’s surface water chlorophyll (ppb), phosphorus (ppb), and Secchi depth (meters) data comparison. Colored areas represent the long-term range of values, from minimum to maximum. Area thickness indicates frequency of measurements at that value. Area thickness increases as more measurements are reported at that value. The vertical black line represents the long-term average value. The large red dot represents 2023’s average value. The small red dots represent individual readings taken in 2023.
Gloeotrichia echinulata (a type of cyanobacteria (blue-green algae) commonly found in low-nutrient waters) can be seen with the naked eye. Gloeo density is reported as a value ranging from 0 – 6, based on the number of Gloeo colonies seen through a Secchi scope. Higher values indicate more Gloeo colonies. Gloeotrichia echenulata colonies were observed in Crystal Lake beginning in late July with densities ranging from less than 0.5 – 2 on the Gloeo density scale
