If that maxes out the depth of the lake, it might not have a thermocline.
Mermet springs is a dive facility. This will give you an idea of the drastic change once you hit a thermocline.
Surface: 86°F | 15' - 25' Visibility
15 Foot: 82°F | 15' - 25' Visibility
20 Foot Platform: 81°F | 15' - 25' Visibility
45 Foot: 55°F | 20' - 30' Visibility
55 Foot (Thermocline): 51°F | 25' - 40' Visibility
85 Foot Platform: 42°F | 25'+ Visibility
Bottom: 42°F | 30'+ Visibility