here is some of the work around the Dam that seems new to me. And there's that new rock wall at the start of the Shaw Butte Trail... perhaps it's all related in some way. The disks read: City of Phoenix 7-14A+2020 and the other one is the same except it says 15A. These are on the east side of the dam as are these other two pictures that show rock work and dirt work (looking south in bottom left photo).