Renton: Waterworks Gardens is located near Renton, WA. The trail is primarily used for nature trips and is accessible year-round.
My husband, son and I went for a walk at Waterworks park and then around the treatment plant. The park really is a hidden gem, but it was hard to find. We drove around for a good while before we found the little turn out of a parking area at about 1200 Monster Road SW, just south of the Wesco Building, though the actual entrance to the park is a bit farther north.
We were really frustrated by the lack of signage for parking. Google maps took me on a wild goose chase just trying to find the place. Once we found the garden, though, we loved it. The grotto is very cool.
Bring bug spray! Lots of standing water.
We ended up just walking all the way around the treatment plant back to our car, which wasn't as scenic as the first part, but still a nice outing.
Will likely do again now that we know how to find it and where to park.