The Hinkley Swim Pond beach at 55 Green St. will open for the summer season Thursday, and will remain open daily from 10 a.m. to 5 p.m. The pond has had new sand added as part of its annual maintenance, and the water is tested daily. Bathrooms, a playground, and a concession stand are all available at the beach. Lifeguards will be on duty through Aug. 20. Group or private swim lessons are available at the pond Monday through Friday for prekindergartners and older children, with members receiving a 25 percent discount on lessons. Individual memberships are $50 for residents and $75 for nonresidents, and family memberships are $75 for residents and $150 for nonresidents; there is no fee for ages 65 and older. Memberships are available at the Pfaff Center, 124 North St., and through the town Parks & Recreation Department’s website, www.medfieldrec.com.