I think your WE will do okay and grow okay with water in the high 70's maybe even low 80-81. Above this they could slow down eating until the water cools back to the upper 70's. WE grow well in the upper OH river and other numerous upper midwest waters where water temps get into the high 70's low 80's.

aka Pond Doctor & Dr. Perca Read Pond Boss Magazine -
America's Journal of Pond Management