The graphs below were created from downloaded Long Lake buoy data and are updated every hour while the buoy is in the water ( typically May – November). Combined temperature and oxygen sensors measure conditions at every other meter (3.28 feet) from near surface to near bottom at the deepest point of the lake’s north basin.
This graph shows temperature at different depths in the north basin of Long Lake. During the spring, temperature readings are close together and the lake is well-mixed. As summer progresses, the lake stratifies (large temperature difference between depths) and lake mixing is greatly diminished. In the fall, both surface temperature and temperature variation with depth decreases until the lake mixes entirely (turnover) and becomes the same temperature throughout.
This graph shows dissolved oxygen concentration at different depths in the north basin of Long Lake. Oxygen conditions in the 8-10 mg/L range indicate that water is saturated or nearly saturated with oxygen, depending on temperature. When levels reach 2 to 5 mg/L, fish become stressed and will die below those concentrations. At 0 mg/L (anoxia), chemical changes at the sediment-water interface can enhance recycling of sediment phosphorus back into the water column.
This graph shows the 6-hour moving average value for the chlorophyll sensor at 5 m (16.4 ft). This sensor measures chlorophyll by fluorescence and gives an estimate of algal biomass at that depth. Values greater than about 7 µg/L are considered high. The fluorescence response of algae cycles naturally through the day and those fluctuations are visible in the plot.