I met a walker arriving out of this trail who thanked me for waiting. I thought this might descend into Marshall Park but was told it just lead to Lancaster.
Thursday, March 25, 2021
45.44991388888889, -122.69551944444444
google map 
45.45048611111111, -122.69495277777779
BOUNDARY 45.4483839, -122.6988700
BOUNDARY 45.4523374, -122.6918041
This swampy bit of private property was clearly fed by stream somehow but that wasn't obvious. That is SW Lancaster Road beyond.
This must green into a little meadow come summer. Those are a couple of beige Adirondack chairs at the far side of the swamp. enlarge