LEA visits Holt Pond once a year in late August. This year, the chlorophyll concentration was below the long-term average, the total phosphorus concentration was above the long-term average, and the clarity reading was near 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 that total phosphorus concentrations, chlorophyll concentrations and clarity readings are stable. This year’s surface water temperature was warmer than last year’s surface water temperature. Oxygen depletion was observed in the bottom half of the water column. Gloeotrichia echenulata colonies were not observed in 2024.
Holt Pond’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 2024’s average value.
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 not observed in Holt Pond in 2024.
