With a catchment area of 563km² the Mid-Brisbane catchment accounts for a small but vital area of the Brisbane River catchment. The Mid-Brisbane Catchment contains the section of the River below Wivenhoe Dam and to the Mt Crosby Weir. It is dominated by the 61km ‘macrochannel’ which is an important conduit of the water supplied from Wivenhoe for treatment at Mt Crosby and the Lowood Water Treatment Plants. As such, the catchment is strategically important to SEQ, and indeed Queensland, being the main water supply intake catchment for the region, providing drinking water for three million people in SEQ.
Lockyer Creek enters the catchment below Wivenhoe and in high flow events it can impact on the catchment. Black Snake Creek is a tributary which contributes significant salinity due to underlying soils. The nearby Lockyer sub catchments of Woolshed and Plain Creeks have similar issues.
Protecting the macrochannel and the quality of the water within the macrochannel is the main issue for this catchment. Bank slumping and erosion risks have been studied. The banks are mainly stable but high risk areas exist. The re-suspension of sediment can occur in high flow rain events such as input from the Lockyer. A concerted effort to protect the entire macrochannel and riparian zone through a number of different actions is appropriate. As the River is continually in flow due to water supply releases, it is attractive to recreationalists.
As the 2013 Australia Day weather event showed, the risk of siltation on the functioning of the Water Treatment Plants, while of low frequency, is of potentially catastrophic consequences. As a general rule, any contaminants entering the 61km stretch that is the Mid-Brisbane River result in increased treatment costs for the region’s community and businesses. There is also the benefit for downstream communities and users of Moreton Bay from the improved water quality within the Brisbane River.
Mid Brisbane Catchment Action Plan