Each cache has a treasure card inside. Take one of each cache and bring it to the visitor center to claim your prize and get a stamp for your Three Dam Tour. One cache is only accessible during the hours of the visitor center and you have to claim your prize at the visitor center too. Make sure you have enough time to finish the challenge at this site. If you don’t have a GPS unit, you can borrow one in the visitor center.
Make sure you also grab a stamp for the Three Dam Tour. If you don’t have a passport yet, ask for one.
A non-trackable Geocoin, which is very nice. This was the final dam on my Three Dam Tour and that’s why I also got the D³ Tour Patch.