Holt Pond is sampled by LEA once per year in August. The long-term average reflects data from 2000 to 2023. The average Secchi disk reading for 2023 was 2.7 meters, which falls into the low clarity range. The Secchi disk did not hit bottom in 2023, however, it has in years past. This indicates that long-term Secchi depth may not be a reliable indicator of historical water clarity. The total phosphorus reading of 15.7 ppb falls into the high range. The chlorophyll-a reading of 1.6 ppb falls into the low range. Long-term trend analysis indicates chlorophyll-a concentrations in Holt Pond are stable and total phosphorus concentrations are stable. Gloeotrichia echenulata colonies were not observed in Holt Pond in 2023.
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 2023’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 2023.
