TheGoolwa Barrages comprise fivebarrage structures in the channels separatingLake Alexandrina from the sea at the mouth of theRiver Murray and theCoorong inSouth Australia. They were constructed principally to reduce salinity levels in the lower reaches of the River Murray, Lake Alexandrina and Lake Albert, but also to stabilise the river level, for both upstreamirrigation and pumping.
Prior to the construction of the barrages, during periods of low river flow, tidal effects and the intrusion of seawater were felt up to 250 kilometres (160 miles) upstream from the mouth of the River Murray, approximately as far inland as the river port at present-daySwan Reach.[1][2]
From the 1900s, with the advent of large irrigation schemes, landowners along the lower reaches of the river strongly urged for the construction of barrages, primarily to keep the water fresh in the lower reaches of the River Murray, as well as Lake Albert and Lake Alexandrina.
In 1931, theMurray-Darling Basin Commission authorised the construction of five barrages. Work commenced in 1935 and was completed in 1940. South Australia'sEngineering and Water Supply Department undertook the project, with costs shared equally by the governments of South Australia,Victoria,New South Wales and theCommonwealth of Australia.
The system consists of five barrages extending fromSir Richard Peninsula in the west to Pelican Point on the northern side of the mouth of the Coorong in the east, crossing five channels between the mainland and three islands. From west to east, the five barrages are named Goolwa, Mundoo, Boundary Creek, Ewe Island and Tauwitchere.[2]
The Goolwa Barrage connectsSir Richard Peninsula on the mainland35°31′43″S138°48′29″E / 35.528552°S 138.808077°E /-35.528552; 138.808077 withHindmarsh Island35°31′24″S138°48′33″E / 35.523210°S 138.809190°E /-35.523210; 138.809190. This barrage includes alock, which measures 30.5 m by 6.1 m.[2]
The Mundoo Barrage connects Hindmarsh Island withMundoo Island.[2]
The Boundary Creek Barrage connects Mundoo Island with Ewe Island.[2]
The Ewe Island Barrage connects Ewe Island with Tauwitchere Island.[2]
The Tauwitchere Barrage connects Tauwitchere Island with Pelican Point on the mainland. The lock in this barrage, provided for fishing boats, measures 13.7 m by 3.8 m.[2]
The barrages are listed as a National Engineering Landmark byEngineers Australia as part of itsEngineering Heritage Recognition Program.[3]