Depicted below is a summary of the dissolved oxygen (DO) testing to-date for 2013. It includes the results from the East Basin, which demonstrates the summer stratification phenomenon, as well as sampling results from various shallow areas around the lake.
East Basin Dissolved Oxygen Profile
In comparing these DO results with those of 2012, we see increased lake water temperatures ( between 2 and 2 1/2 degrees Celsius) and DO concentrations about the same.
Area Sampling of Dissolved Oxygen
This chart depicts DO concentration at a number of shallow areas around the lake (see chart in the DO Sampling Protocol section). A number of readings were taken at a depth of approximately one meter and the results shown as an average of those readings. For reference, the orange line (Lake – Location #1) is the reading obtained at the East Basin at the one meter depth, so you can see how DO concentrations vary in relation to the lake in general. Remember, these readings were taken around dawn. Sampling of the same areas in the afternoon showed DO concentrations 1 ½ to 2 ppm higher as a result of photosynthesis.
Comparison of 2012 to 2013 Dissolved Oxygen Profiles
The graph below shows the DO readings from both 2012 and 2013. It is quite congested, but if you follow the legend (dotted lines are 2012 results) you should be able to see the differences. As mentioned earlier, the first thing that you will note is the higher 2013 lake temperatures in the hypolimnion (lower lake water). Secondly, you will note that 2012 DO concentrations at and slightly below the thermocline were higher than 2013. This is because the colder water is more dense and thus, can hold more oxygen.