Improving and developing the Collie River is an important priority for the Shire of Collie. The Shire, guided by the Weeds and Waterway Advisory Committee, is implementing the following strategies to improve the health and amenity of the river and tributaries.
The Collie River was choked with Nardoo plants. Nardoo is an introduced weed which slowed the flow of the river, was unsightly, and prevented the river from being used to its full potential including swimming, boating and fishing.
The Shire of Collie, in partnership with the University of Western Australia, investigated various methods to control the Nardoo including herbicides, plastic solarisation, mechanical excavation, mechanical harvesting and the use of a grappling hook. Success was achieved through the development of a compound herbicide called Reglone. The Shire has implemented a Nardoo Treatment Program using Reglone for the last few years that has successfully brought the weed under control.
Control of Nutrients
Favourable conditions for the growth of Nardoo and many other river weeds are created by the quantity of nutrients being washed from the town of Collie into the river. These nutrients are mainly from fertilisers used on gardens and reserves. The Shire of Collie, through the Weeds and Waterways Advisory Committee, is currently implementing a number of solutions to reduce nutrient levels and improve the health of the river, ensuring that the Nardoo and other weeds do not return. These solutions include:
- Building riffles to oxygenate the water
- Controlling nutrients placed on Shire land
- Planting trees to shade the river (depriving the weeds of sunlight)
- Increasing the depth of water in the river using Venn Street boards
- Constructing and planting nutrient stripping basins at inlet points
- Providing educational material to the public
- Personal responsibility
The work undertaken to date has proven to be very effective and has improved the health and aesthetic of the Collie River. Approval ratings for the river have increased with each community perception survey conducted by the Shire.
While further work still needs to be completed by the Shire and State Government, the community too has an essential part to play in the control nutrients running into the river by following the Tips to a River Friendly Garden below.