Sewerage connections at eight local towns will be investigated and prioritised, according to Baw Baw Shire's new onsite wastewater management plan.
With more than 4500 onsite wastewater systems recorded in Baw Baw, Cr Suzanne Allen said the importance of a robust management plan "cannot be understated."
Her summary was made as Baw Baw Shire councillors unanimously adopted the new plan at a recent council meeting.
Cr Allen highlighted that about 13,601 of the 36,371 developable lots within the shire were not connected to the reticulated sewer systems, making it "imperative to implement high standards of design and management".
When connections to systems are impractical or impossible, Cr Allen said septic tanks with dispersal or recycling components were essential.
"The council, in collaboration with water corporations and key stakeholders, must establish policies and procedures that facilitate responsible development whilst safeguarding public health and the environment," she said.
The plan's risk analysis indicated Buln Buln, Darnum, Erica, Neerim Junction, Nilma, Noojee, Thorpdale and Walhalla presented the highest risk to public health and the environment. It recommended further consideration be given to the investigation, prioritisation and feasibility for these townships being connected to the reticulated sewerage network.
Whilst a majority of Baw Baw exhibited a low to medium risk, the plan highlighted Noojee as a high risk to human health due to a higher proportion of septic tanks.
The plan also noted council had an electronic database of applications and permits for onsite wastewater management systems dating back to the early 2000s, with hardcopy records to the 1970s.
Of the 13,601 unsewered lots in the shire, about 4522 are registered with council. It is expected a number of lots have systems that are unknown due to being constructed without a permit or before permits were required, or when records were interrupted by amalgamation.
The plan proposes a 13-point action plan and timelines, including the introduction of a monitoring program by September this year.