Engie have released their Concept Master Plan for rehabilitation of the Hazelwood mine, and envisions the Morwell River being re-diverted through the mine land “once fill [water] is assured”. Yallourn also plans to interconnect their full pit lake with the Morwell River, which is currently diverted through the centre of the mine – via an aqueduct on a raised earth embankment. Morwell River would then flow into the Latrobe River.

The volume of the Yallourn lakes will be 725 Gigalitres, which is over ninety times greater than Lake Narracan (7GL) and three-and-a-half times Blue Rock Lake (approx. 200GL). Hazelwood’s lake volume (600GL) would be greater than Sydney Harbour (500GL). Professor Rae MacKay noted in the Mine Fire Inquiry Day Three transcripts, “The implications of water… are significant. These mines will become fairly significant sinks for water… It may be that that change in the hydrology will become a permanent feature of the region.” The advice suggests that just these two full pit lakes would create their own micro -climate with significant humidity from evaporation – being 10-14GL per year.

The ongoing talks by the Department of Environment, Land, Water and Planning (DELWP) and mine operators centres around piping alternate water sources (desalinated or recycled water) to provide another water source for pit lake fill.

Desalination is fairly straightforward, but Class A recycled water could have many complications. There are current state and national reviews, and relevant guidelines, on the use of recycled water. The guidelines note that where recycled water can be used, environmental management plans, auditing and monitoring must take place. However, it appears that some emerging contaminants (eg. PFAS, pharmaceuticals, phthalates) that cannot presently be removed from final treatment could be overlooked in the new guidelines. This means pit lake rehabilitation using recycled water could be importing any number of chemicals flowing through Hazelwood, through Yallourn and then into the Latrobe River system, flowing on to the Gippsland Lakes.

Another cause for concern is that if the increased rainfall created by the evaporation will be so significant that the valley experiences rain laced with chemicals. More research is needed. Alternately, the future vision for the Latrobe Valley could be that river flows are separated from lake bodies in a ‘locked -up’ lakes system with no public access.

First Published in Yallourn North Connection