I have run two different races at Champoeg State Park before, and the gently rolling bike paths are beautiful and relaxing. Both times I got really close to a new PR in the respective distances (10k and half marathon). The out-and-back course starts at the west end of the park and passes the day-use area twice (for the 10k), which makes it really convenient if you’re bringing along your cheering section. The 20k and 30k are two and three loops, respectively, of the same out-and-back course.
This race offers three different distances: 10k, 20k and 30k. What’s unique is that if you run the 20k or 30k, you are automatically also getting official times for the shorter distances, so presumably it is possible to end the morning with three different age group awards! The 10k is also part of the ORRC 10k series, and you are able to upgrade to the longer distances (the first 10k loop will count towards your series time).
To register for the race, go to the online registration page. There is no mail-in registration.