Rivers
The major river systems of the Northern Agricultural Region form a part of the four drainage basins: Murchison, Greenough, Moore – Hill and Yarra-Yarra. The rivers only flow after substantial rainfall and the lower reaches of the rivers are open to the ocean during high winter flows. The lower reaches of the rivers comprise of estuaries, which provide important habitat and refuge areas for many aquatic organisms, fringing vegetation and associated fauna.
There are a number of river systems that are recognised for their significant ecological values including the Greenough, Chapman, Hill and Moore river estuaries, which are significant migratory bird feeding areas.
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Data sourced from the Department of Water and Landgate SLIP.
Arrowsmith River
Drainage Basin Length (km) Catchment Area (km2) Average Stream Salinity (mg/L) Key Characteristics Greenough 82 1,605 3000-35000 Commences near Arrino, north west of Three Springs. It has no clearly defined ocean outlet, and drains into a subterranean cave system. Bowes River
Drainage Basin Length (km) Catchment Area (km2) Average Stream Salinity (mg/L) Key Characteristics Greenough 50 715/td> 1000-35000 Drains the farming areas in and around the Waterloo Range, comprising small estuaries, with average depths of less than 3 metres. Only open to the ocean for a few days, mainly during the months of June and August. Buller River
River Length (km) Catchment Key Characteristics Buller 10 33.9 The Buller River head waters rises 25 km north of Geraldton and meanders in a southerly directions before discharging into the Indian Ocean approximately 4 km north of Drummonds Cover. Chapman River
Drainage Basin Length (km) Catchment Area (km2) Average Stream Salinity (mg/L) Key Characteristics Greenough 80 1,644 3000-35000 Originates east of Yuna and drains the farming areas of the Chapman Valley. The river enters the ocean within the northern suburbs of Geraldton and is only open to the ocean during winter flows. Gingin Brook
Drainage Basin Length (km) Catchment Area (km2) Average Stream Salinity (mg/L) Key Characteristics Moore-Hill 46 1,370 < 1000 Gingin Brook is the only remaining freshwater creek passing over the Swan Coastal Plain. It has almost permanent flow since it is fed by springs as well as general groundwater. For information on the allocation plan click here.
Greenough River
Drainage Basin Length (km) Catchment Area (km2) Average Stream Salinity (mg/L) Key Characteristics Greenough 306 12,568 3000-35000 Originates in the pastoral region north east of Mullewa, and flows through farming areas, entering the ocean at Cape Burney, south of Geraldton. The sandbar across the estuary is only opened by significant flows. It contains numerous pools including Eradu, Beetalyinna and Ellendale. Hill River
Drainage Basin Length (km) Catchment Area (km2) Average Stream Salinity (mg/L) Key Characteristics Moore-Hill 124 3,721 1000-3000 Originates east of Badgingarra and enters the ocean halfway between Cervantes and Jurien. The estuary is blocked by a sandbar for most of the year and the rivers major tributaries are the Munbinea, Coomallo, Boothendarra and Winjardie Creeks. The lower reaches are also groundwater fed. Hutt River
Drainage Basin Length (km) Catchment Area (km2) Average Stream Salinity (mg/L) Key Characteristics Greenough 50 1,254 1000-35000 Drains the farming areas in and around the Waterloo Range, comprising small estuaries, with average depths of less than 3 metres. Only open to the ocean for a few days, mainly during the months of June and August. Irwin River
Drainage Basin Length (km) Catchment Area (km2) Average Stream Salinity (mg/L) Key Characteristics Greenough 160 6,072 3000-35000 Originates east of Mullewa, and has middle and lower reaches with perennial flow due to discharge from the groundwater systems. The river enters the ocean at Dongara and the mouth of the river is a coastal lagoon system, which is blocked by a sandbar for most of the year. Moore River
Drainage Basin Length (km) Catchment Area (km2) Average Stream Salinity (mg/L) Key Characteristics Moore-Hill 288 13,450 3000-35000 The Moore River’s eastern reaches (Moore River East) which originates near Dalwallinu, and northern reaches (Moore River North) commences east of Coorow. The major tributaries are the Coonderoo River and Gingin Brook. The Moore River enters the ocean at Guilderton and the estuary is only open to the ocean for a few weeks each year. Murchison River
Drainage Basin Length (km) Catchment Area (km2) Average Stream Salinity (mg/L) Key Characteristics Murchison 300 14,850 3000-35000 Lower reaches are listed on the Directory of Important Wetlands. Enters the ocean at Gantheaume Bay. River mouth is permanently open to the ocean due to dredging. Major tributaries are the Hope, Yalgar, Roderick and Sandford Rivers. Nambung River
River Length (km) Key Characteristics Nambung 22 The Nambung River meanders between the towns of Cervantes and Badgingarra. The river ceases within the Nambung National Park in Karst terrain approximately 9 km south east of Cervantes. Yarra Yarra and Monger Lakes
Drainage Basin Length (km) Catchment Area (km2) Average Stream Salinity (mg/L) Key Characteristics Yarra-Yarra and Moore-Hill 350 17,700 >35,000 Yarra Yarra Lake is the terminal point for an extensive chain of salt lakes. The major lakes in the system include Nullewa Lake, Weelhamby Lake, Mongers Lake, Lake Goorly, Lake DeCourey and Lake Hillman.Approximately 42 % of the Yarra Yarra Drainage Basin is in the NAR. Due to the basin’s flat terrain, drainage is generally uncoordinated, with each lake having its own internal drainage system. However, in wet years the lakes overflow along a broad drainage line, ending up in Yarra Yarra Lake. It is uncertain if there is a surface or groundwater connection between Yarra Yarra Lake and the Coonderoo River, a tributary of the Moore River.