This place is dog heaven. Mostly Coot Lake, which is just a big swimming pool for local dogs. There is a nice flat trail around Coot Lake which also connects to trails that skirt the Boulder Reservoir if you’d like a longer walk.
The parking area is on 63rd St, just north of the Diagonal Highway. There is a small parking area right on Coot Lake which will usually be full, but there is plenty more across the street.