The Clay County Sheriff's Office Lake Unit is responsible for patrolling all County parks.

The largest of these is Smithville Lake. Deputies patrol three camp grounds with approximately 750 campsites spread across three camp grounds: Crows Creek Camp Ground, Camp Branch Camp Ground, and Smithfork Camp Ground. The Lake unit patrols approximately 30 miles of trails, including asphalt, mountain bike, and equestrian trails.  The Lake Unit patrols two swim beaches and 16 picnic shelters. The Lake Unit also is responsible for patrolling lake access points. The Lake Unit assists the Missouri State Highway Patrol with water rescues and boat tows. It also assists Clay County Parks, U.S. Army Corp of Engineers, and the Missouri Department of Conservation with a managed archery hunt, managed goose hunt, managed youth hunt, and a managed handicap deer hunt. The Lake Unit also provides water safety for two triathlons.  

The other County parks and historic sites the Lake Unit patrols include Rocky Hollow, Tryst Falls, Jesse James Birthplace Farm and Museum, Mt. Gilead Church and School, and Pharis Farm.