The Washington Secretary of State's office on February 5, 2013, stated in an electronic letter (ticket:2013020710002046) that the works of the Redistricting Commission are public domain, but attribution is requested:
The work of the Redistricting Commission is public domain; however, we ask that you cite the Washington Redistricting Commission as the source of your posting.
Carolyn Berger
Elections Division
Office of the Secretary of State
Phone: 360.902.4180

As stated on Washington state’s official website:
3. Public access to information
In the State of Washington, laws exist to ensure that government is open and that the public has a right to access appropriate records and information possessed by state government. At the same time, there are exceptions to the public's right to access public records that serve various needs including the privacy of individuals. Exceptions are provided by both state and federal laws. All information collected at this site becomes public record that may be subject to inspection and copying by the public, unless an exemption in law exists.