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Salinity Provinces in the Mallee Catchment Management Region

The Mallee CMA Region is the largest CMA Region in the state covering over 17% of Victoria's northwest. It contains a number of ephemeral stream and lake systems which drain north towards or into the Murray River. The catchment landscape consists of the low lying and undulating Riverine Plains, and the ancient dune systems, the Mallee Dunefields, with limited topographic highs. Elevation extends from 150 m (AHD) in the southwestern corner of the ‘Big Desert’ towards 30 m (AHD) at Lake Wallawalla.

Average annual rainfall decreases slightly to the north ranging from 330 mm at Ouyen (south) to 300 mm at Mildura (north). Temperatures are extreme and vary seasonally. Maximum summer temperatures are commonly greater than 40 C throughout the region and winter minimums may fall to -5 C.

Native vegetation makes up 38% of the land cover, much of which is designated as public land. There are extensive ephemeral wetlands throughout the regional, some of which are RAMSAR listed. The majority of the land is broadacre farming dominated by cropping and dryland pasture for livestock production (sheep meat and wool, beef cattle). Irrigated horticulture in the Mallee extends along the Murray River from Nyah to the South Australian border and plays a significant role in salinity management.

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Salinity is an important waterway and land management issue in the region and entrenched within the Regional Catchment Strategy (RCS). Salt loads into the Murray River are high and have a major negative impact on in stream health. Large groundwater discharge complexes called “Boinka”, considered a primary salinity process, dominate salinity mapping. Large shallow saline depressions are common, some of which are “Pink Lakes” due to the presence of carotenoid producing algae.

Groundwater Flow Systems within the region are generally of regional scale. Salinity has been recorded at over 1130 individually mapped units1, covering an area of nearly 130,000 hectares1 of the CMA. Where similar hydrogeological processes contribute to the salinity occurrence throughout the landscape, individual Salinity Provinces have been defined. Eleven such Salinity Provinces, nine of which are 'High' priority, have been distinguished in the region as a tool to understand the salinity processes and management options better.

The Mallee CMA has an extensive range of online materials (maps and documents etc.) which outline the biophysical assets of the catchment, as well as their major risks (including soil and water salinity). This material also outlines the programs and projects currently being completed by the CMA to protect and enhance these assets. An example of this is the Mallee CMA ‘Mallee Salinity Workshop Report (2012)’, which provides extensive information about both dryland and irrigation influenced salinity processes and occurrence in the region. The link to this document (and others) can be found at the base of this page.

Provinces displayed in this map are clickable or use the table of links provided

Map of Mallee CMA Region with Salinity Provinces mapped
Salinity Province 63 Salinity Province 79 Salinity Province 74 Salinity Province 100 Salinity Province 41 Salinity Province 103 Salinity Province 118 Salinity Province 92 Salinity Province 22 Salinity Province 138 Salinity Province 61

Province Name
No.
Area of Province (ha)
Recorded Soil Salinity Area 1 (ha)
Soil Salinity Area (% of SP)
Cowangie - Underbool
22
215,930
29,186
13.52%
Hattah Lakes
41
50,310
1
0.00%
Lascelles
61
221,110
318
0.14%
Lindsay - Wallpolla
63
130,980
25,867
19.75%
Mildura - Colignan
74
124,710
3,131
2.51%
Morkalla
79
65,830
2,469
3.75%
Ouyen
92
158,780
3,596
2.26%
Raak Plains
100
124,050
26,008
20.97%
Robinvale - Nyah
103
122,440
6
0.00%
Tyrrell Basin
118
380,010
36,454
9.52%
Yaapeet
138
93,750
264
0.28%

1 Please Note: The ‘Recorded Soil Salinity Area’ and ‘number of individually mapped units’ indicated in the CMA text and/or table, comprises the total geographic area or number of sites that have been mapped as having, or showing symptoms of dryland soil salinity at some time (past or present). As dryland salinity occurrence in the Victorian landscape exhibits many different levels of severity and can change due to climate, landuse and vegetation, previously mapped areas may no longer be showing symptoms. In addition, as not all parts of the state have been mapped, or mapped in the same way, the mapping may not have captured some occurrences.
Recorded soil salinity mapping used for these pages does not cover irrigation regions. Instead, depth to watertable and watertable salinity mapping has been used to convey the threat of high watertables on soil waterlogging and/or soil salinisation.
Please contact the Department, your Catchment Management Authority or your rural water provider for more information about salinity in your location.


Relevant Information



Links to further reading and material related to the Mallee CMR Mallee CMA region on VRO Mallee CMA (external link)
Mallee Catchment Management Authority region on VRO
Mallee Catchment Management Authority (external link)
Mallee CMA ‘Regional Catchment Strategy ’ (RCS)
Mallee CMA ‘Mallee Salinity Workshop Report (2012)’
Mallee CMA ‘Waterway Strategy’
Information about bores and groundwater resources in the Mallee CMA can be found on the Visualising Victoria’s Groundwater (VVG) website
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