Who is responsible for managing Campvale Canal?
Hunter Water owns the last 800m of Campvale Canal down to the pump station and we undertake regular maintenance in this section to remove excess vegetation which may prevent water flowing to the pump station and into Grahamstown Dam.
Upstream of Hunter Water’s land, Port Stephens Council is responsible for the maintenance of Campvale Canal. Council cleaned a large amount sediment and vegetation out of this area in late 2019 to improve water flow.
Why does the area in and around Campvale Wetland become inundated after rain?
After rain, properties in and around Campvale Wetland have been experiencing inundation (flooding), often for several days at a time. The area is very flat so is prone to flooding however after heavy rainfall the main factors influencing the level of inundation are the canal getting clogged with vegetation, increased urbanisation within the catchment increasing runoff, sediment and other debris within the canal and a natural feature known as ‘the pinch” which is an uphill slope of the canal and inhibits the ability for water to flow efficiently to the pumping station. All these factors restrict the rate of drainage of flood waters out of the wetland area.
Why can't the area be drained more quickly?
The Campvale Wetland acts as a system to filter water before it reaches the pump station and is pumped into Grahamstown Dam. Sediment and nutrients are removed as the water flows through the wetland and comes into contact with sunlight.
Pumping the water more quickly from the area will result in poorer quality water being pumped into our drinking water supply.
(The water cannot sit in the wetland for an extended time, however, or the quality will reduce due to lack of oxygen.)
What is 'The Pinch'?
The Pinch is a natural land feature which includes an upward sloping section of land within Campvale Canal. The pinch has the effect of reducing the flow of water out of the Campvale Wetland area down to the Campvale Pump Station.
Why is it taking so long to find a solution?
Finding a solution has been challenging. The solution needs to balance the need to remove water from the wetland area to minimise flooding but allow enough time for the water to be filtered naturally in the wetland area to improve water quality.
We need to make sure the water quality leaving the Campvale Wetland area is as good as possible to ensure high quality, safe water enters into the water supply catchment of Grahamstown Dam. After the water leaves the Dam it is treated before being provided to you, our customers.
How will the proposed solution reduce flooding?
We are still working out how best to undertake the planned on ground works however the combination of these works together with regular maintenance, will reduce the likelihood of periods of inundation that last more than 10 days.
It is estimated that the changes will reduce the frequency of these long periods of inundation by more than 75%. This means that the likelihood of prolonged inundation will have only a 25% chance of occurring in any one year.