Storm & Flood Damage Recovery in Gresham, OR

That is antecedent conditions doing the work. After weeks of continuous December rain the basin is saturated and has no capacity left, so an ordinary system produces runoff that the same storm in October would not. The channel is low-gradient through a developed area, which means it fills rather than flushing. Watching how wet the preceding month has been predicts flooding here better than the size of any individual forecast.

That is common here because the ground changes over short distances. Some of this area is free-draining Columbia outwash gravel and some is heavier soil developed on volcanic material, and they behave in opposite ways. An infiltration solution that works beautifully on gravel does nothing in heavy soil, and vice versa. A shallow test pit on your own lot in the wet season is worth more than any amount of neighborhood consensus.

That is the more common local damage and it accumulates rather than arriving. Through a wet season the ground under the house stays close to saturated and moisture moves continuously into the framing above. There may never be standing water. A sealed ground vapor barrier does far more than ventilation, since outdoor air in a Pacific Northwest winter is not going to dry anything, and February is the month to inspect.