The Hills and Fleurieu Landscape Board allege that approximately 700 dams in the region are illegal.
High-res aerial imaging has found around 400 new dams have been built illegally in the last 10 years, with another 300 being enlarged without permission.
The State Government has committed additional funds for compliance officers to check local properties, with illegal dams to be removed.
General Manager Michael Garrod says those doing the wrong thing are jeopardising water availability for landholders who need it, as well as impacting environmental targets for water catchments.
They say they’re pleased that most landholders have chosen to rectify the situation once notified, however note that penalties will be handed down for those who refuse.
