Salinity Province 27, Douglas Depression

The Douglas Depression Salinity Province forms an extensive, low-lying valley that slopes to the north and has been postulated as the former path of the Glenelg River. Landuse is a combination of dryland grazing and cropping with significant areas of native vegetation. About 5% of the province is mapped as saline, which is significantly above the statewide (per province) average.

The province is underlain by a regional scale Groundwater Flow System (GFS) of marine and alluvial sediments overlain by local to intermediate scale aeolian, alluvial and paludal GFSs. A chain of lakes that stretches 70 km north south dominates the province and 11 of these wetlands are listed as important for migratory birds. Some of the lakes were primary saline discharge zones however, following the clearance of the original vegetation, wetter climatic periods saw watertables rise and appear under the remaining freshwater lakes and other low-lying areas, all of which are now effected by secondary salinity.

Best management practices include avoiding the disturbance of known waterlogged and saline sodic soil areas and protecting them from damage. Farming should concentrate effort on adjacent up-slope soils to increase perennial pastures and native re-vegetation to reduce recharge during wet periods.