31° - 35° F
One interesting thing I noticed is when I went there early in the season, I had gone to two other area lakes of similar size and found barely a couple inches of ice, but Rinehart had almost 6". I also noticed a spring bubbling through the ice where the weeds end on the east side of the boat landing, and another deeper in the weeds to the west.
Good luck to anyone that tries this lake. Nice place, but not very fishy.