Lake Saltonstall, referred to locally as Plug Pond, is a small lake located in the southwest park of the Winnekenni Park Conservation Area, near Winnekenni Castle, in Haverhill, Massachusetts. Accessible via the main entrance on Sanders Road or through trails leading from Winnikenni Castle, the lake has an area open to the public, and another reserved exclusively for Haverhill residents. During the summer months, residents may enjoy a swimming area, municipal boating programs, picnicking and bathroom facilities once they have shown proof of residency and paid a parking fee of $2.00 per vehicle. Those who walk enter for free.