This park is about 25 miles north of Las Cruces, NM. Coming from the south, once you leave I-10, you wander through pecan groves until you get to Radium Springs.
It's easy to get lost getting here: my GPS app tried to take me to the day-use area, which is closed and padlocked. I stopped at Fort Selden, just up the road from the day use area, and got directions, which were easy to follow. All on paved roads, but still, better signage would help, New Mexico!
The Visitor Center was closed, with signs advising that you check in with the Camp Host (site 9) if you have questions. The sites in my "neighborhood" (Cactus Patch) all have water and electricity. There's a common holding tank dump station right by the visitor center. I have yet to locate trash cans or a dumpster, but I haven't looked all that hard.
Map coordinates: 32°29'35" N, 106°55'10" W
The big question about this park is why it's here at all. It is on the way from Las Cruces to Hatch and then on north to Albuquerque. It's not all that attractive -- flat scrub as far as the eye can see, with the exception of some hill off to the east. The actual dam and the Rio Grande isn't visible from the park. It does have a really cool playground for kids, right by the visitor center, and lots of little trails and cactus gardens to explore.
I reserved and pre-paid 2 nights here. Knowing what I now know, this place rates a one-night stopover. It makes Rockhound, where I was the last couple of days, look much more attractive. I said I wouldn't stay here again, not because there's anything really wrong, but because Rockhound and City of Rocks are much more attractive options in this part of New Mexico.
The crescent rolls were delicious: