Submitting to the Oregon Encyclopedia project has changed...
they now have a once-a-year workshop for those wanting to write articles.
Outside of that, they do work with educators. What this means for you, if you wish to submit an article is,
1) email me your intention to submit, with your final article attached,
2) I email the submissions to the coordinator, and
3) she will review them and bring articles that pass review (I don't know the requirements for this) and then the board will decide at their next editorial meeting (sometime in March or April).