Serpentine RAP

Earlier this week Peel-Harvey Catchment Council (PHCC) announced that draft version of “Serpentine River Action Plan” is now completed and final report will be published and launched soon. PHCC partnered with Urbaqua to complete and deliver the Serpentine River Action Plan (RAP) as part of the ‘Connecting Corridors and Communities – Restoring the Serpentine River’ project. The RAP has certainly garnered local attention, including an article in the local paper.

The ‘Connecting Corridors and Communities – Restoring the Serpentine River’ project is a collaborative conservation initiative, working with private landholders, local Noongars and volunteers to improve the heath, biodiversity and function of the Serpentine River. The project is supported by the Peel-Harvey Catchment Council, through funding from the Alcoa Foundation’s ‘Three Rivers, one Estuary’ Initiative.

As the Alcoa Foundation Initiative’s name suggest, the Serpentine River is one of the three main rivers that discharge into the Peel-Harvey Estuary, along with the Murray River and Harvey River. As with the other main rivers, historical clearing and agriculture have impacted the Serpentine, along with construction of dams and levees. The RAP has been prepared to understand the current state of the river and guide management and rehabilitation actions for the future of the river.

The RAP addresses approximately 38 km of river from Lowlands Reserve Conservation to the Peel Harvey Estuary (see the map below). The majority of the Serpentine River here is concealed behind the Kwinana Freeway, with most motorists not appreciating hidden gem next to them.

To assess the current condition of the river, a field based assessment was completed via foot, 4WD, boat and helicopter (only the Serpentine Airfield prevented the deployment of drones). The assessment methodology is based on the Department of Water and Environmental Regulation South West Index of River Condition. Urbaqua and PHCC provided training to the volunteers and Alcoa graduates who assisted in completed the assessment in April and May 2019. The methodology was devised to allow volunteers to complete the assessment in future, providing data to evaluate the success of rehabilitation work by comparing scores against the baseline conditions established in the RAP.

The 38 km of river was divided into 8 separate reaches, each demonstrating unique characteristics. A quick visual tour of the reaches is provided in the gallery below, showing the change from a small, heavily vegetated river (Reach 1) into a heavily modified drain system with artificial levees (Reach 2 to 4), into a meandering, wide river (Reach 5) and finally into a 200 m estuarine system in Mandurah (Reaches 6 to 8).

The highlight of the field assessment was avoiding most of the snakes that call the river and wetlands home – except this guy insisted on saying hi. Some of our other new friends are shown in the gallery too.

The RAP documents the current conditions of the river, noting areas of erosion, dense weeds, degraded riparian vegetation and poor water quality. It also highlighted areas with remnant vegetation in good condition, diverse stream habitats and minimal bank erosion which serve as reference sites to guide rehabilitation works. As a management tool, the RAP provides priority and long term recommendations for restoring the waterway that PHCC will look to deliver in the coming years.

Unfortunately since the completion of the draft RAP there have been two fires in Baldivis and Hopelands that have reached the river. The first jumped the Serpentine River in Reach 2 and was caused by the vehicle malfunction. The second hit Lowlands Reserve and Reach 1 and the cause is not yet known.

The final document will be published by PHCC soon so keep an eye out on their website for further details.   

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