Hogandoc1
They used to hold the Regatta here, back in Stone Valley's heyday. They have a nice ropes course, nature center, and a small lake that they have finally refilled. Too few concessions, but with a little work and advertising, they could bring it back to where it was in the 1970's. The lodge is clean, the rental cabins could be a frugal alternative for lodging on football weekends, if you don't leave town then.
isilwath
Stone Valley is lovely. Many trails and places to picnic. There's boating and boat launches, but no swimming. A nice place for a day trip.
JB866
Stone Valley is a lovely place to take an afternoon hike. They have a bird sanctuary with bald eagles, owls and many types of other birds. Lake Perez, which is part of Stone Valley, is currently dried up. There are however pretty streams flowing by the hiking trails.