NICA have continued to monitor water quality in the Noosa River and its tributaries, and to look for ways which we might employ to make improvements.
At the intersection of Hofmann Drive and Rene St Noosaville, just behind Noosa Civic, is a great example of how Nature can purify polluted water.
Stormwater drains flow into a low lying pond or wetland area filled with grasses, some shrubs and small trees. It’s home to families of moorhens, and I’ve seen swans and magpie geese there too.
It’s fed from stormwater drains from the nearby factory area and part of Noosa Civic with typical polluted drain water, measuring slightly acidic pH 6.26, turbidity 30 NTU, and low level of dissolved oxygen 37%.
This water then percolates through the wetland and exits about 75 m to the south as a small stream which then flows to Eenie Creek. Through the wetland the water is transformed into a perfectly clear stream with reduced acidity measuring pH 6.7, turbidity measuring only 0 – 1 NTU, and dissolved oxygen restored to 63%. The vegetation in the swamp has done a great job of filtering and consuming the pollutants.
These low lying wetland areas are precious natural water purifiers which we can harness to improve the quality of the water entering our river without any artificial treatment being required. Some 35 years ago most of Noosa Waters was one such wetland before the construction of todays urban and canal estate, but there have been numerous areas of wetland retained to assist with pollutant reduction before drainage is discharged into the river.
Other such natural areas can be seen around Noosa, such as the Wallum plains, and it’s important that they be retained and added to whenever any urban development is contemplated. It would be really beneficial if all new drainage could be directed through such purifying natural areas rather than flowing direct to the river as done in the past. Small bio-retention basins are now being installed in some locations, they just need to be a lot larger to be as effective as Nature.
Bruce McConkey
