Lava Pump House map overlay *PIC*

A while back someone from the Friends organization was interested in trying to find the out buildings near the pump house. I think that they wanted to do some sort of brochure for a walking tour. At that time I posted a map that was overlayed by hand. Since then I have found a better technique for putting together the overlays which results in better accuracy. Anyway, here is a fresh overlay using the latest colorized aerial images.
One thing that I noticed is that I couldn't get Lava tank to line up. If I line up the tank, the ROW doesn't line up at all. Was a replacement tank built at Lava at some point while the old one was still in use? Is it a map error? Hmmm...
This overlay shows the new pump house, old pump house, pumpers house and a WC.