longtime hidden

We started clearing the stream in front of the shop. Its the lowest part of the land and has not been cleaned in about 5 years. The most downstream part of the stream is covered in "caryso" this is in the “rush family” its like bamboo, a grass that grows 1" thick and 30 feet high, but very weak and fast growing. When I say covered, I mean covered, but only on our side, the upstream side, the other side is filled with many medium size trees that vines have crept up over the last century or so, virgin land and maybe for sale!!!! So the caryso has leaned over onto the other side, as has the trees and vines on the other side leaned over as well, creating a tunnel over the stream, impassable by all but frogs, crabs, snakes, turtles, grasshoppers and who knows what else. So in the tunnel is a hidden natural waterfall dropping 1 foot into a pool that’s about 2 feet deep and 10 feet in diameter. This pool has been here for ages and for a while, locked out from the world. I found this huge white frog, with large green stripes, he hopped up near me to check me out, never seen a human in ages, and I invaded his secret pool, oops. For the moment I would not enter the water. I know that its stream fed, but its possible upstream neighbors may be contaminating it. Also, now is the rainy season and the water is brown from mud and I cant see what might lurk on the bottom to cut my feet.