Upper Preston catchment

The Upper Preston catchment lies on the Darling Plateau upstream of Lowden. It consists of land draining to the Preston River upstream of the gauging station near Ferguson Road, north of the Donnybrook-Boyup Brook Road. Flow is released from the Glen Mervyn Dam to the Preston River for irrigation and the environment.

Most of the catchment remains uncleared and the forested parts of the catchment help to improve water quality in this part of the river. However, the land surrounding the waterways is used for stock grazing which can result in increased sediment and nutrient loading to the Preston River and eventually the estuary. Fertilisation of fruit trees and vineyards can also result in increased nutrient concentrations in the Upper Preston.