... If you had water at SOME POINT after installing Tingass Fjords, and it disappeared later (for instance after installing another add-on to it) then in GENERAL this issue gets solved by running the Repair Utility (Windows Start Menu > FSAddon > Tongass Fjords FSX > Repair), or by re-installing Tongass Fjords X.
If you do NOT have water, but lots of pine trees) after initial installation of TFX, then the terrain.cfg did not get updated properly, and needs a manual update ...
If your boots aren't muddy, you're not in the bush...