The voters pamphlet is for the primary election in May. Some city and county races will be decided in this election and not in November. Just before the candidates Statements section, you should see a page titled 'Closed Primary Elections in Oregon'. That explains which party seats are part of the primary with the final decision in November. If you don't have any, either there are none in your district, or you are registered as a Democrat or Independant.
Remember, all politics are local. Candidates come up through the ranks. The person running for city counsel, county commissioner, or local judge, could very well be determining your future, from a higher seat, years from now. Choose wisely.