Pleasant Valley Beach is the South Shore swimming beach at Moraine State Park, a 16,725-acre park run by the Pennsylvania Department of Conservation and Natural Resources (DCNR) in Muddy Creek Township, Butler County. It sits on Lake Arthur, a 3,225-acre reservoir created by damming Muddy Creek, with 42 miles of shoreline. The park has two swimming beaches; this one is on the south side of the lake, and the other, Lakeview Beach, is about five miles away on the North Shore. The park office and mailing address (225 Pleasant Valley Road, Portersville) are just up the road.

To get there, take US 422 to the South Shore entrance and follow Pleasant Valley Road into the park. DCNR puts the beach about one mile from Route 422 and half a mile past the park office. The Pleasant Valley day use area is laid out as a string of paved parking lots, picnic groves and pavilions along the road, and the beach lots are a short walk from the sand. Portersville is about three miles west of the beach.

The beach itself is a 400-foot strip of turf and sand facing a sheltered stretch of the lake, according to the park's current swimming page (older guides list 1,200 feet and mention a paved path into the water, so expect a mix of grass and sand rather than a long sandy shore). A sand volleyball court and a playground are on the west end. Showers, changing rooms, ADA accessible flush restrooms and a snack bar serve the beach. The park does not post water temperatures or swim-area depths; expect the lake to be coolest in early June and warmest in August, and DCNR publishes a lake depth map for anyone who wants detail. There is no current to speak of, but wind can push chop across the open water.

There is no fee. Pennsylvania charges no entrance or day-use fees at any state park, and the Pleasant Valley parking lots are free. The beach is open daily from Memorial Day weekend through Labor Day, 8:00 a.m. to sunset, unless otherwise posted, and the rest of the park is open sunrise to sunset all year. Swimming is at your own risk: DCNR does not list lifeguards here, so watch children closely. Pets are not allowed in the beach area, and smoking is banned on the beach and in the water, with designated areas nearby.

The main thing to plan around is that the beach depends on its bathhouse. In 2014 the park kept Pleasant Valley Beach closed through the Fourth of July while sewer lines and a pump station were replaced, because the swim area cannot open without working restrooms and showers. Lakeview Beach stayed open during that work, so it is the fallback if the South Shore is posted closed. Boats with motors up to 20 horsepower and plenty of sailboats use Lake Arthur, so stay inside the beach area. In winter the cove beside the day use area is used for ice skating, but the park does not monitor ice thickness.

The Pleasant Valley area has three reservable pavilions (Pleasant View, Pleasant Grove and Windy Knob) that are free first come, first served when not reserved, plus open picnic tables. The 1.9-mile Pleasant Valley Trail starts across the road from the Pleasant Valley Picnic Area, and the Sunken Garden Trail loops through wetland and along the lake from the nearby non-powered boat launch, a handy put-in for kayaks and canoes.