The area has a mediterranean-type climate with cool, wet winters and warm to hot summers, with significant summer rainfall. Most of the rain comes from fronts associated with low-pressure systems passing over, or to the south of the area. Pan evaporation rate is about 1200 mm. per annum, and is less than rainfall in 4 to 5 months of the year. Average monthly minimum and maximum temperatures range between 14°C and 26°C in summer and 7°C and 16°C in winter.

The geology of the catchment consists largely of the Plantagenet Group of Tertiary sediments - siltstone, spongolite, minor sandstone, peat and conglomerate. There are minor and major aquifers, ranging from fresh to saline condition. Springs are numerous throughout the catchment.

From this page you will find basic information about the catchment - the countryside, its history, its geography, the variations in water-related parameters over time and references to more detailed relevant published work on the catchment and the region.

Catchment statistics:

Subcatchment areas

Total catchment area	330 square kilometres	100%
Marbelup Brook sub-catchment	125 square kilometres	38%
Five and Seven Mile Creeks sub-catchment	60 square kilometres	18%
Torbay Main Drain (Unndiup Creek)	115 square kilometres	35%
Coastal draining dunes	30 square kilometres	9%

Land use

Remnant vegetation	108 square kilometres	33%
Open water and wetland	5.2 square kilometres	1.6%
Grazing	170 square kilometres	51%
Timber Plantations	17 square kilometres	5%
Other land uses (cropping, horticulture, dairies, piggeries, wildflowers, small holdings etc.)	29.8 square kilometres	9%

Length of catchment waterways	180 kilometres
Rainfall range	800 - 1000 mm. per annum
Estimated number of properties	563