Well, I'm a bit late to this party but stumbled across this thread and was interested. I grew up on Lake Worth, the south side, in the '50's and occasionally saw a PBY land and take off but always on the far north side of the lake Casino Beach. The photo had me really confused because I assumed the anchorage would have been close to the foot of the Ft. Worth Army Air Base (Carswell AFB) runway until I looked at a map of Lake Worth and realized the orientation of the photo as described above is correct. That is Goat Island in the background and, indeed, had the camera been panned a bit more toward the south and east (left), Whiting Castle would have been in the frame. It also means that Casino Beach and the Lake Worth Casino are just to the right foreground of this picture and the Jacksboro Highway is just out of the frame foreground as well.
Regarding the Marine Air Base on Eagle Mountain Lake; my buddies and I used to go to the drag races out there until they shut the whole thing down.
Anyway, interesting bit of history. Thanks.