Even though the Board 19 Stream does not join with the Board 66 Stream; it still form an impassable barrier on account the stream is Flooded; see below specifically sentence in red.
A4.3 BYPASS: Bypass enables unbroken Infantry to move through a building/woods hex without entering the obstacle in that hex (and consequently having to pay the two MF cost of actually entering a building or woods), whenever that obstacle does not physically touch the hexside being Bypassed.
Bypass cannot be used to skirt the edges of any other terrain feature (including gully-woods), nor an obstacle that is Ablaze or contains an armed non-Disrupted (19.12) Known enemy unit. Hexes containing rubble or Wire cannot be Bypassed. A hexside forming a part of a Wire Location, or covered by a Water Obstacle (24L9-M9), may not be Bypassed (B26.44) on either side of the hexside; roadblocks also have Bypass restrictions (B29.4). SMOKE does not prevent Bypass but adds to the MF cost (24.7) of transit through the hex. Bypass may be used in a mined woods/building hex but does not prevent mine attacks. Use of Bypass movement does not prevent placement of a DC (23.3) or SMOKE grenade (24.1). Bypass must be announced with the expenditure of MF as the unit moves inside the building/woods hex. A unit that decides to occupy an obstacle it is currently Bypassing must pay the entire in-hex MF cost to enter that obstacle even though it is already in the hex.