Lindsay, Mulcra and Wallpolla islands cover over 26,100 hectares of River Murray floodplain, forming part of the Chowilla floodplain and Lindsay–Wallpolla Island Living Murray icon site. The floodplain is characterised by a network of permanent waterways, small creeks and wetlands. The larger, permanent waterways–Lindsay River, Potterwalkagee Creek and Wallpolla Creek–form the southern boundaries of the site and create large floodplain islands with the River Murray to the north.
Naturally, these waterways and wetlands would flow and fill in response to high water levels in the River Murray. However, the regulation of the River Murray has reduced its influence on the Lindsay, Mulcra and Wallpolla system.
Although large floods can still occur, flows through the system are mostly regulated by the River Murray locks 6 to 9. Regulators and containment structures have been built throughout the Lindsay, Mulcra and Wallpolla floodplain and are used to help protect the environmental values at the site.