not sure where you got your information, this is from the fishing regulations. 10 feet is largest you can use.
"
CAST NETS- Forage fish and minnows may be taken with cast nets. It is unlawful to use a cast net with a square mesh less than 1/4-inch or larger than 1 inch on a side, or with a diameter of greater than 10 feet. It is illegal to use a cast net within a distance of 1000 feet downstream from any dam posted with Division of Wildlife signs indicating cast net use is prohibited".