In the Centennial Accords, there is a whole lotta words on "government to government", "agencies/representatives " etc but not a lotta words (ie any) on "public participation". State law, state courts have little to no leverage in the negotiation format between the state and the tribes as far as requiring "open meetings".

http://www.goia.wa.gov/government-to-government/data/centennialaccord.htm