Midger (grid reference ST797895) is a 65.7-hectare (162-acre) biological Site of Special Scientific Interest straddling the border of Gloucestershire and South Gloucestershire, notified in 1966 and renotified in 1984. Since the last revision in 1974, the size has been reduced to a 56-hectare (140-acre) site. It lies east of Hillesley, Gloucestershire and north of Hawkesbury Upton, South Gloucestershire.