Salinity Province 65, Loddon Plains

The Loddon Plains Salinity Province is the largest province in the North Central CMR covering over 250,000 ha. The north and central parts of the province are predominantly irrigation areas while dryland farming dominates the south. The province is underlain by a deeper, regional scale Groundwater Flow System (GFS) in the alluvial plains, including an extensive ‘deep lead’ (paleo-river channel) aquifer system. Local to intermediate scale GFSs in Quaternary alluvial, lake and lunette sediments overlies this. The deeper aquifer system exerts upward pressure on the overlying aquifer systems and discharge has occurred at deeply incised drainage lines eg. at Bears Lagoon and Serpentine. The deep lead can provide good quality water (~1500 ppm) for irrigation in places, while the overlying aquifer often has a shallow watertable and the groundwater is typically much more saline (6000+ ppm).

An extensive network of bores records groundwater levels in both the upper and lower aquifers and provides data to manage the deep lead resource and support Salinity Management Plans in the irrigation areas. More recent soil salinity mapping has indicated a much reduced area of salt affected land, probably due to the decade long period of drought from 1999 to 2009.