This is not comprehensive but this is what I have so far.

Northwest Paddle Festival May 11-12 (this coming weekend!!!)

http://northwestpaddlingfestival.com/

Canoe Families 4th annual celebration June 2nd

http://www.parks.state.wa.us/CivicAlerts.aspx?AID=385

South Sound Traditional Inuit Kayaking Symposium is June 8-10

http://www.qajaqpnw.org/

Kitsap Peninsula Water Trails: Ride the Tide June 16

Kitsap Peninsula Water Trails: Ride the Tide June 16, 2018

Kayak the Cowlitz: End of the Summer float Sept 2

https://www.eventbrite.com/e/kayak-the-cowlitz-sunday-sept-2nd-2018-labor-day-weekend-tickets-44822750052?aff=es2

 

What other events are there within a reasonable drive?