If that makes you hungry, there are two concession stands in the park. Also, fishing and boat rentals are available. In short, Moraine Hills State Park is a great getaway not far from the Chicago area. I happen to like the smell of the lilacs and other wildflowers in the spring. The fall colors are pleasant, too.
Water is available at the trailhead.
All services are available in McHenry and Crystal Lake. Your main concern will be other trail users on pleasant days. You're never too far from a parking lot. You'll find a phone at the park office and at McHenry Dam. The USGS 7.5 minute quad is Wauconda, with a small portion of the park falling into the McHenry quad.