Thank you !!First of all - there's not such thing as a "Dry" Water Obstacle...so that SSR is not within the rules, IMHO.
But I get what it means.
Movement from M7 to M6 (which I assume is what you mean) is an Abrupt Elevation change (B10.5).
So for Infantry it would be 5 MF (1 [to go "down" the intermediate level] and 4 [moving into a building while moving "up"]).
For a vehicle is would be 2 MP to go "down" and then e.g., 10 MP (for a fully-tracked) to go into bypass in M6.