2005 – Lake Mokoan Decommissioning Project: Working with the Community to Maintain Supply Reliability

Graeme Hannan, David Jeffery

Lake Mokoan is a 365 GL capacity off-stream storage in the Broken River basin in northern
Victoria. Lake Mokoan will be decommissioned to provide 44 GL of water savings to benefit the
River Murray and the Snowy River. The Victorian Government has committed to maintain
reliability of supply in the Broken River supply system by implementing a package of offset projects.
The paper describes the community engagement process implemented by Goulburn-Murray Water
to steer the selection and implementation of the offset projects.

A reference committee of Broken systems irrigators was established in late 2004 to provide advice
to Goulburn-Murray Water and the Department of Sustainability and Environment on the package
of offset measures to be implemented to maintain the supply reliability once the 365 GL capacity
Lake Mokoan was decommissioned, leaving the 40GL capacity Lake Nillahcootie as the sole
storage in the Broken River irrigation system.

A REALM based system simulation model was refined to test the sensitivity of the parameters
defining the system reliability and to assess proposed offsets measures. The paper describes the
modelling which was undertaken and the evaluation and ranking of offset projects priorities.
The community engagement process is described. The paper concludes with commentary of the
lessons learned from this process.