The Swan Reach and Morgan ferries are set to close from 7pm tomorrow due to rising water levels along the River Murray, the state's transport department has announced.

The Department for Infrastructure and Transport said the ferries are expected to remain closed while local water flow exceeds 120GL/day.

Alternative river crossings for the Swan Reach ferry are the Walker Flat ferry or Murray Bridge and Blanchetown Bridge.

For the Morgan ferry, the alternative river crossings are the Cadell ferry and the Blanchetown Bridge.

The Lyrup and Mannum upstream ferries closed late last month due to high water levels.

All other ferry services are currently operating as normal.

The department said it was closely monitoring water levels to keep ferries operating as long as it is safe to do so, however, with conditions changing quickly, ferries may have to be closed at short notice.

To find the status of all River Murray ferries, as well as latest information during the Murray River floods, visit www.sa.gov.au/floods.