Parkfield drain catchment
The Parkfield drain catchment includes the southern part of the Myalup horticultural district, just to the north of the Leschenault Estuary.
Horticultural land uses generally have high fertilisation requirements, in particular phosphorus. Because of the close proximity of the horticultural district to the estuary on sandy soils and the direct connection of the Parkfield Drain, there is little capacity to buffer surplus fertiliser. As a result, this catchment likely contributes a substantial nutrient load to the northern extent of the estuary. This part of the estuary is poorly circulated and experiences regular algal blooms in summer.