Never been there, but the 2018 Fishing Forecast said :
"Very good numbers, but large proportion is smaller size. Most keeper fish range in sizefrom 9-11 inches for white crappie and 7-9 inches for black crappie. Popular with bankanglers due to many bank access areas." And it also warned : "Zebra mussels and hydrilla are present at Dewey Lake. Boaters are asked to take measures to prevent the spread of thesedamaging non-native invasive species by properly inspecting and disinfecting boats, trailers and equipment."
Statewide creel limit & size limit would apply .... which means there is no minimum size limit & the creel limit is 20/day/person.