If you use the launch alot you can buy a annual boat launch pass for $35.00 .

Fee Information
$ 7 / Day Pay at parking permit meter at the boat launch.
$35 / Resident Annual Pass This pass is valid Jan 1 - Dec 31. A copy of the towing vehicles registration and a piece of identification to verify residency is required.
$70 / Non-Resident Annual Pass This pass is valid Jan 1 - Dec 31. A copy of the towing vehicles registration is required.

Annual Boat Launch Parking Permits can be obtained at the Community Center at Mercer View.

Mercer Island boat launch