Lewes Brooks is a 339.1-hectare (838-acre) biological Site of Special Scientific Interest south of Lewes in East Sussex.

[1][2] The Falmer-Glynde and the Ouse valleys meet in Lewes Brooks, and the Upper and Lower Rises are the remains of the chalk uplands eroded by the Ouse.

[3] This site is on the flood plain of the River Ouse, and has fields separated by ditches.

Variations in salinity from brackish to spring-fed, together with periodic clearing of ditches, produce a variety of habitats.

The site is home to a diverse array of invertebrate fauna, especially water beetles.