I live in Portland, OR and have recently moved into a house with a small backyard complete with two mature oak trees. Whether due to the shade or the alterations made to the soil by having these two trees in a small area (or all of the above), the grass that was in the yard when I moved in July is now gone. I now have packed dirt for a backyard and the winter rains fast approach. Oh, and I have a very active herding-breed dog who loves to run, so I need to find the right grass/non-grass/combination that will grow fast, tolerate lots of wet in the winter and not a lot of sun... oh, and lots of foot/paw traffic once it is established.

Any suggestions?

Thanks!