A free outdoor discovery program, hosted by the Butler County Parks and Recreation Department, will feature “Things That Go Bump in the Night” at 7 p.m. today in the Carousel Shelter at Alameda Park. Call 724-284-5383.

Jennings Environmental Education Center, Route 528, Brady Township, will host “Little Mouse on the Prairie,” about small mammals that live on the center's prairie, from 10 to 11:30 a.m. Saturday, and a “Prairie Bloom Hike” from 2 to 3:30 p.m. Sunday. Jennings is open 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.

Moraine State Park hosts the Lake Arthur Regatta this weekend at the Pleasant Valley area on the South Shore. Hours are 9 a.m. to 10 p.m. Saturday and 10 a.m. to 5:15 p.m. Sunday. Live entertainment, water, air and land events, craft and food vendors, children's activities, Smokey Bear, and canoe, kayak, and sailboat races are just of few of the planned activities. Saturday night there will be fireworks over the lake. Music performances take place both afternoons. Donations are accepted, but admission and parking are free. Visit www.lakearthurregatta.org or call 724-368-8811.

McConnells Mill State Park in Slippery Rock Township, Lawrence County, hosts “A Taste of History: Dutch Oven Cooking” from noon to 3:30 p.m. Aug. 11. Park at Kildoo picnic area and hike down to the mill. Mill Cleanup Day will be Aug. 17. The mill is open 11 a.m. to 4 p.m. Fridays, Saturday and Sundays through October. Tours, which last about 45 minutes, are available at 1 and 3 p.m. Fridays, Saturdays and Sundays. Call 724-368-3612.