McConnells Mill State Park, Slippery Rock Township, just over the Butler County line into Lawrence County, will host "Art in Nature" at 2 p.m. Sept. 20. Meet in the courtyard of the Old Mill ready to design and create artwork. The annual Heritage Festival will take place there from 10 a.m. to 7 p.m. Sept. 27 and 11 a.m. to 6 p.m. Sept. 28. The Old Mill has a new turbine and offers demonstrations from 11 a.m. to 3:30 p.m. Fridays and 11 a.m. to 5:30 p.m. Saturdays through October. Admission and parking are free. Call 724-368-9320.

Jennings Environmental Education Center, Route 528 near the intersection of Routes 8 and 173, will host a Healthy Hike from 6 to 7:30 p.m. Oct. 1. Jennings is open from 8 a.m. to 4 p.m. weekdays and on weekends as scheduled. The trails are open daily from sunrise to sunset. Call 724-794-6011 to confirm programs.

Moraine State Park will be the site of "Guide to Geocaching," 2:30 p.m. Saturday. Meet the park naturalist at the Pleasant Valley picnic area, on the South Shore.