If you're out by Banks, I would try Tillamook State Forest. There are miles of logging roads that wind through there, and most of the timber companies have very detailed maps of areas they are working or plan to work, including streams and other water bodies. How to get ahold of said maps is another question. However, a friend of mine uses a software program he purchased at Dick's Sporting goods that is put out by National Geographic, I think. It's specifically tailored to Oregon, and allows you to print your own topo maps and customize features you want highlighted or included with each print. I thought he was a little nuts for getting it because it's kinda spendy ($99.99) until we used some of the maps he printed. I've never seen a better map, and you can zoom in pretty close on a certain area to print giving you a good picture of where you want to go. It also syncs with certain hand-held GPS units so you can download maps and pre-programmed routes directly into your GPS, if you use one. It also worked great for deer season, giving us a much better picture of unfamiliar terrain.
The other thing that comes to mind is calling the ODFW biologist assigned to the region you're in. You'd be surprised how much information they can give you that you'd never get anywhere else. The nature of their job requires them to be in the field a lot, so they get to know an area pretty well. I think you can get the name and number for the office in your area from ODFW's website. The trick is catching them while they're in the office. Good luck!
