Mid Preston catchment
The Mid Preston catchment lies on the Darling Plateau and consists of land draining to the Preston River between Boyanup and Donnybrook. Joshua Creek drains the north of the catchment.
Most of the catchment remains uncleared, including Boyanup State Forest. However the land closest to the waterways and in the east has been cleared for grazing. This catchment contains septic tanks which likely contribute excess nutrients to the river. The Donnybrook wastewater treatment plant is also located in this catchment, but the plant discharges to a woodlot with high nutrient retention soils and is unlikely to contribute notable nutrient loads to the river.