In the back yard, we have three cisterns that get progressively smaller and lower. The largest one overflows into the next and that one overflows to the lowest one. The frogs love these cisterns. In the first picture you can just barely see a green tree frog in the overflow pipe from the largest cistern. We never noticed this last year so it appears to be a new habit by the tree frog. In the second picture is a frog convention with eight frogs hanging out in the lowest cistern. It is hard to see because of the bright sunshine but they are having a great time. In deference to the frogs, we've stopped taking water from the lowest cistern.