Only other game we've seen that region of Tamriel in was TES I: Arena, where it appears to be in a more mountainous, potentially snowy, region. Considering a decent bit of lore regarding climates and geography has shifted since Arena, especially when provinces have been fully fleshed out for the main series games, the status 3rd/4th Era Bangkorai is known, but also unknown.

If rumors about the location of TES VI being in the Iliac Bay, containing Hammerfell and/or High Rock, are true, then we may very well see the region. But, if it doesn't appear there, Beyond Skyrim will showcase the region in their Iliac Bay release. Based on this map (here), the region does appear to be in a similarly verdant environment, though the lake does appear to be just the river.

But, then again, ESO has taken some liberties with geography. Adding mountains where they weren't before to form zone borders, neglecting natural progressions between biomes, and even rotating the Imperial City ~30 degrees. It would appear that they chose to name the upper portion of the Bjousae River as a "lake", due to the fact that they significantly widened the entire river, making it more of an extended inlet.