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Gardner River at a glance
Average annual catchment rainfall:   1350 millimetres
River length:   35 kilometres
Extent of tidal influence:   Five kilometres
River health:   no significant pollution
       Gardner River view

The Gardner River discharges directly into the ocean, with a rock bar, open most, if not all, of the year. The river flows most of the year, and the surface water is fresh (less than one ppt). However, when river flow slackens, sea water flows back in underneath the outflowing fresh water, with little mixing between them. The lower reaches of the river have depths of three metres or more, but rock bars and fallen logs obstruct boat passage beyond about three kilometres from the ocean.

Water temperature probably ranges from 10°C. or less in winter to 24°C. in summer. Summer recordings show the surface water at 24°C., with deep water temperature decreasing gradually to 20.5°C. at three metres.

Total phosphorus readings range from 0.01 to 0.08 mg/litre. Part of the upper catchment is cleared, mainly for cattle grazing, but the greater part remains uncleared.

Further Information:

Estuaries and Coastal Lagoons of South Western Australia. Broke Inlet and other estuaries of the Shire of Manjimup. Environmental Protection Authority; Perth, Western Australia. Estuarine Studies Series Number 6: September 1989

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