The Wenatchee Area Genealogical Society would be your best bet for information. Check out there web site here:

http://www.wags-web.org/index.html

Also, check out this site for Washington State death"s

http://search.labs.familysearch.org

and the Washington State Digital Archives here:

http://www.digitalarchives.wa.gov/

If I knew the range of dates you are looking at, it would help.