Yes, you need a Discover Pass to visit Lake Wenatchee State Park. The Discover Pass is a vehicle permit required for day-use access to Washington state parks, including Lake Wenatchee State Park. The pass costs $30 annually or $10 for a one-day pass. You can purchase a Discover Pass online, at a state park, or at various retail locations. Note that the Discover Pass is not required for overnight camping, as camping fees already include the cost of the pass during your stay.