New to the area and decided to try this park based on the reviews. Chapparal Park itself is really nice, and I recommend skipping the dog park portion and just walking your dog through the rest of the park. The "active dog" section is too small - maybe an acre and 1/2 for each of the "active" and "passive" dog areas. The active dog area was overcrowded and smelled strongly of urine, which is what you're going to get with such a small space. My dogs are vaccinated, but I'm still concerned about health risks from the crowded, unsanitary conditions. There was a good size puddle that several dogs used to relieve themselves in, then other dogs that were playing a game of chase ran right through it.
It's obvious that the city works really hard to maintain this space the best they can and the grass was in decent shape, but it you're used to larger parks where your dog can really run and you can walk, you'll be disappointed. Overall, didn't have any trouble with other dogs while we were there and the people seemed friendly enough.