A few months ago I received a text from a local fisherman who had been to Alamo Lake and saw something unusual floating in the lake. He sent me a picture and at the time it looked like a polystyrene structure with some kind of plants on it.
He asked me if I knew what it was, and I didn’t. But I found out. I obtained information courtesy of Pam Kostka, Operations Project Manager for the Los Angeles District of the US Army Corps of Engineers.