Moving low and along the edge of the streambed, erring toward the treeline for cover and concealment and avoiding the depression, while approaching the temple from the south would makes the most sense in my opinion. Given the stream [i]is[/i] still moving with some water, I would rather avoid splashing about in it or having us get ambushed while lower than the enemy, where we'd have to fight up and out. Sticking to the edge of the treeline on its southern side should allow us to avoid almost any detection if the enemy is rooted in the town, namely on the other side as you said, and all is obscured by foliage.

We could even advance through the trees when drawing closer on our approach, hopefully avoiding detection that way as well.