Springfield's Millrace has a long history and is the subject of a recent restoration project. This photo shows the Millrace just before the waters enter the Willamette River at Island Park. At the top you will see an observation deck. But this area has not yet been restored.
Information and history of the millrace is here - http://www.ci.springfield.or.us/pubworks/MillRace.htm I am anxious to see it when the restoration is completed.

Pictures of progress of the restoration efforts are shown here - http://springfieldmillrace.org/