Hey there Elric- check out reply #42 in the "Too many leads" thread. Also, check out "Willamette river landings in Marion county". A little bit of a drive, maybe worthwhile?
Here's a few more, there may be duplicates.
#186- is an archeaological site, from 680 AD to late 1700's possibly early 1800's.
#85- Warrior rock. Conoe burial site, rock ledge against which Sauvie's island was formed.
#86- Clackstar- large village, up to 1200 inhabitants.
#87- Prehistoric village
#11, 12 and 13 are fossil sites. Mostly gastropods, fossil shells, and pelecypods (sp?)
All of the purple circles are villages, I won't detail them all. Not much for notes on any of them.
#1 (brown circle) is Corbelt or Corbelle warm springs. May be private land. NE 1/4 Sec.27 T 1N, R 4E Used by early travelers to the region.
#30- Portage for immigrants. Cascade locks to Bonneville dam.
#21 (the star) is an old fort. I have no notes on it, but its probably well known being so close to Sauvies island.
Then there are a couple treasure stories related to Portland. One is a cache, hidden near the old pike road. Its called the Sims or Simes treasure. there is also a cache of buried gems from a jewelry store robbery just south of Portland, but details are sketchy. There is the Flavel house cache, and the Coxcomb Hill cache in Astoria. All are outlined in Ruby El Hult's book, Treasure hunting Northwest. Another good one by her is Lost mines and treasures of the Pacific Northwest.
Unlike most other "Lost Treasure" books, Ruby was quite a researcher and she lists her sources and details extensively.