The Corangamite Catchment Management Authority (CMA) is working with Barwon Water, Colac Otway Shire and Department of Transport to mitigate the impacts of localised flooding downstream of the Upper Barwon, including the closure of Birregurra-Forrest Road and some local roads.
The West Barwon Reservoir is spilling due to higher-than-average rainfall experienced during certain times this year, which is not unexpected or uncommon.
The Upper Barwon is a highly modified system with the advent of farming roads, construction of the reservoir, extensive clearing of native plants, the introduction of agriculture, variable climate conditions, and introduced species such as Glyceria and willow. There are many factors at play and there is no simple solution to mitigate the impacts of changed flow conditions.
The Corangamite CMA commissioned expert engineers to conduct a risk assessment of the site last weekend and provide advice on alleviating localised flooding and protecting the road from inundation. The preferred short-term option is to look at a localised blockage point downstream, judicious clearing of Glyceria upstream and downstream, and fixing minor breakout points.
The Corangamite CMA is currently unable to access these sites because it is too wet. We will do as soon as access is possible.
Corangamite CMA CEO John Riddiford said all agencies are committed to working with concerned landholders to look at longer-term options to manage the river health.
Mr Riddiford continued, “The authorities are meeting with landholders and interested members of the public on Friday to hear their concerns and look at mitigation of damage to public assets like the Birregurra Forrest Road. Our main priority is working together to keep it open where possible”.
Barwon Water Managing Director Tracey Slatter said that above-average rainfall this season meant the West Barwon Reservoir was over-flowing, as it was designed to do when full.
“It has done this regularly since it was built in the 1960s including four other times in the last 20 years.
“We are proactively supporting Corangamite CMA and the Department of Transport to respond to the flooding and impact to the Birregurra-Forrest Road downstream of the reservoir.
“We are also keen to work with landowners and Corangamite CMA into the future about how we can collectively improve the health of the West Barwon River, like we are currently doing in parts of the East Barwon River.
The Corangamite CMA has committed to investing in the Upper Barwon River and working with local landholders into the future said Mr Riddiford.
The Corangamite CMA will establish a high-level coordinating group across agencies and working with the local community to develop longer term options for implementation.