If you are fishing from a boat in the Catfish Derby, your vessel must have a current Lake County mussel screening sticker.  If the vessel is registered in California it must also have a current state mussel fee sticker.

Lake County Law: 

Requires screening of all trailered water vessels.

All watercraft launched in Lake County MUST display a current Lake County mussel sticker as proof of screening. This is in addition to the State DMV sticker that is proof of the State's mussel fee payment.  See the Press release for further clarification. 
Does NOT apply to canoes, kayaks, car-top boats, float tubes, rafts, wind surfers/boards, boogey boards, nonmotorized paddle boats, and nonmotorized sail boats that are eight feet or less in length.
Bans the disposal of live bait and any liquid that contains or has contained live bait into Lake County water bodies.
Establishes violation as a fine of up to $1,000 with boat impoundment. 

More information on Lake County's mussel inspection requirements is at http://www.nomussels.com/