Work is underway to restore a 240ha area of Crown Land in Baldivis east of Kwinana Freeway and south of Karnup Road. The land contains a mixture of Threatened Ecological Communities (Flora and Fauna), Conservation Category Wetlands, constructed wetlands, former grazing land and drainage channels. Works to be undertaken include River Restoration, water treatment and control, revegetation, pest and weed control as well as monitoring.
The 240ha area of Crown Land in Baldivis east of Kwinana Freeway and south of Karnup Road is a mixture of Threatened Ecological Communities (Flora and Fauna), Conservation Category Wetlands, constructed wetlands, former grazing land and drainage channels. These are located in a landscape which is recovering from past land management and drainage activities as well as the impacts of Climate Change. The area has many Conservation Category Wetlands and is simply crying-out for support with a very high chance of recovery. Plans include restoring a section of the Serpentine Drain to provide deep pools and refuge habitat for fauna.
In 2025, PHCC was awarded almost $2m over a period of 3 years to improve the ecological health and condition of the area. In the proposed works, PHCC will be guided by our Urban Rivers Team (see photo above) and are involving Stakeholders from State and Local Government and Indigenous Rangers and Elders, with key involvement of Water Corporation Department of Water and Environmental Regulation and Department of Biodiversity, Conservation and Attractions. .
These works all impact ono flows into the Peel-Harvey Estuary and the improvements gained in this project will assist the water quality in the Ramsar 482 area.
The Serpentine River (or under its Indigenous name “Waangaamaap Bilya”) catchment, was brought under European settlement from the 1890’s. A series of very heavy rainfall years in the late 1910’s and early 1920’s, caused large areas of inundation and made the land unworkable for farming. That instigated the government of the time to undertake major drainage works that drained much of the Serpentine River catchment from Cockburn and Byford in the north to Nambeelup in the south. The drainage removed much of the inundation from the farmland, but had the detrimental impact of draining wetlands and much of the landscape of groundwater; with much of that water now being discharged into the Peel-Harvey Estuary. Climate change has exacerbated the problem with “step-change” reductions in rainfall (and flow) occurring in about years 1970 and 2000 with rainfall reductions totalling 23% of pre-1970 rainfall in the catchment. At the latter time, Serpentine River changed from a perennial river (only drying in the most severe droughts, to a seasonally inundated river with long dry periods of 3-4 months each year. This impact of also felt by the may wetlands of the Swan Coastal Plain which also struggle with low water levels and high concentrations of nutrients and salinity.
PHCC and many of our science-based partners believe that these changes can be mitigated and turned around. Yes, the summer-autumn period is very dry and is likely to continue to be so. However, Rerpentine River flows discharging to the estuary average over 30GL per year (since 2010). If even a small proportion of that can be retained in our wetlands or riverine pools, that will be a big bonus for the environment!
Serpentine River at Peel MD confluence [29/07/2025]
Serpentine Wetland CCW when full [PMD018 – 12-08-2025]
Same Serpentine wetland when almost dry [PMD018 – 20-05-2025]
To facilitate this vision by PHCC, in 2025, PHCC was awarded almost $2m over a period of 3 years to improve the ecological health and condition of the area. This funding is hopefully the first step in a longer-term project to undertake restoration of the local environment and its community, flora and fauna. The project includes the following components:
- Undertake River Restoration on sections of the Serpentine River near the Peel Main Drain confluence; works will include deepening the river pools to connect groundwater, provide perennial habitat for indigenous fauna in logs and other large woody debris, replant local flora and protect the Banksia Woodland Threatened Ecological Communities (TEC’s) on the river banks and the vulnerable Carter’s Freshwater Mussel which lives in the riverine pools.
- Enhance the heavily degraded Conservation Category Wetlands (CCWs) of the original Serpentine River channel that existed before the river was drained and contained within embankments. These CCW’s have a lineal length of 4km with vegetation that is severely under threat from lack of water over summer. On the higher ground adjacent to these CCW’s are Herb-rich Shrubland TEC’s that are also under threat. Both of these assets are affected from reduced available water due to drainage of the local catchment that is encouraged to flow out to Peel MD and Serpentine River.
- Also in the Project area is the PMD-Swales operation. These are engineered structures that are build to divert water from the Peel Main Drain (PMD) through a set of 6 large channels (Swales) to reduce the amount of Phosphorous in the water column. The project has been in operation for the past 3 years with the incremental learnings from each years monitoring being fed into upgraded designs to build on our understandings. The overall aim is to be able to implement our findings of how best to treat high concentrations of phosphorous into the drains, rivers and wetlands in the area to improve the health of the systems.
- Outside the project area is the Peel-Harvey Estuary which includes the Ramsar 482 system. All of our work in the Waangaamap Bilya is also aimed at improving the Health of the Estuary.
Keep an eye out for regular project updates in future editions of Wattle & Quoll. There is an update on the Peel MD Swales Off-line Treatment Project in this edition.
This project is funded by the Australian Government’s Natural Heritage Trust under the Urban Rivers and Catchments Program, with the support of PHCC and the Department of Water and Environmental Regulation’s