Trudau Lake was a small, round pond about 47 yards in diameter. Around the edges, the water was shallow and amazingly clear, but toward the middle it was a deeper, dark blue. I could see fish close to the surface. I immediately recognized guppies, but there were many kinds I didn't know. There were water plants growing under the water and reeds and grasses on northern and eastern edges of the lake.
Water flows into the lake from a spring about a hundred yards west.
Some of the water flows overland into the lake, but most of it goes into the ground 75 feet above and comes out of the limestone rocks on the west side of the lake. The outlet on the east side of the lake is about the same size as the stream above. The water felt warm to the touch. From a raft, I took readings of depth and temperature at various spots in the lake. There seemed to be no indication of the water level changing.