The Environment Canada real-time hydrometric sensor is online for 2018 and transmitting lake level measurements from the Sylvan Lake marina station 05CC003.
This graph shows the change in lake level between May 1 and September 3, 2018.
The historical median lake level on September 1 is about 936.78 metres above sea level. The lake level was 936.62 metres above sea level on September 3.
The almost-linear evaporation rate after about June 10 was (230 mm/83 days=) 2.77 millimetres per day. That drop of 230 mm was a loss of 9.7 million tonnes of water from the Sylvan Lake surface area of 42 square kilometres. That required an input of 23.8 million gigajoules of solar energy to evaporate the water at 15C. If that natural heating was done instead by purchased natural gas at $1.50/GJ, the evaporation cost was $35.6 million on which the lake paid no carbon tax!
Sylvan Lake Watershed Stewardship Society 