In March 2015 Portland City Council voted to ban smoking in all Portland parks.
 

No person shall smoke or use tobacco in any form in any place in any Park. For purposes of this Section, smoking and tobacco are defined to include, but are not limited to: bidis, cigarettes, cigarillos, cigars, clove cigarettes, e-cigarettes, nicotine vaporizers, nicotine liquids, hookahs, kreteks, pipes, chew, snuff, smokeless tobacco, and marijuana.

 
To read the full ordinance:
http://www.portlandonline.com/auditor/index.cfm?c=28627&a=522649