On the way home from our trip to Vegas this weekend we stopped at Yuba Lake State Park, about 25 miles south of Nephi, right off I-15. We pulled into North Beach, not sure what to expect, and were happy to find sandy beaches (no gravel!) and relatively warm (it was only 75 degrees out so we were expecting it to be FREEZING), calm water.
I guess there are a variety of campgrounds and beaches at Yuba - some accessible by car, some only by boat. Some of the campgrounds have restrooms and shade canopies, some are more primitive. The Utah State Parks website says they have a concession where you can buy a hamburger or rent boats, jet-skis, and ATVs, although we saw no sign of the concession area (we weren't really looking for it though).
The other feature it offered was a vague smell of poop.
(I know, that's a glowing recommendation right there. But - I don't know. Them's the facts. We went home and showered THOROUGHLY.)
(I don't know if it USUALLY smells like that or if it was just special for us.)
Poop smell aside (I don't know that might be a dealbreaker for some of you pansies), it would make a nice little day trip.
More info here.