Arne,
Early September would be a great time for trolling in the estuaries of many of the larger coastal rivers, If you are looking to "bank fish" above tide water, it may be a month early. Many of the coastal streams are running very low and warm until after the fall rains begin preventing the salmon from leaving tide water. Once the rains begin, the decomposing Alder leaves stain the water and make visibility poor. That being said, any place with a riffle or pool where you can't see bottom is a great place on most streams/rivers to float some "good" roe through.
Good Luck and Enjoy your trip to The PNW,
MIke