DO and Temp History
About every 2-3 weeks during the summer (and occationally through the ice), we measure the dissolved oxygen (DO) and temperature every meter at the deepest point of Highland Lake (aka Deep Hole). The below heat map shows an annual representation of all values collected as compared to the Secchi (water clarity) measurement.
Following ice-out the surface of the lake heats up and stratifies into layers called the Epilimnion (or the top warm layer), the thermocline / Metalimnion (the middle layer), and the colder Hypolimnion extending to the floor of the lake. During the colder months at the end of the year the surface water cools, becomes dense and sinks causing the lake to "turn over" or mix again. This late season mixing process also reoxygenates the water column.
Temp and DO each have a strong bearing on many physical, chemical and biological processes in our lake ecosystem. DO levels are affected by water temperature, but also the algae/organic decomposition process which consumes oxygen. They both are also critical for the type of fish that can thrive in the lake and a reason why Highland Lake does not naturally support cold water fish like trout and salmon who require temperatures below < 24C and DO levels no lower than 4-5mg/l.
Below are archived plots of DO and Temp that Keith Williams has been creating for the past 30+ years