It's not just Sydney's drinking water that's being threatened by bushfires.
The Murray Darling Basin Authority are warning that forecast rain in the parts of the burnt out Upper Murray catchment could impact water quality in Hume Dam, situated on the Murray River.
MDBA Executive Director of River Operations, Andrew Reynolds said the predicted rain this weekend was much-needed to replenish depleted storages but could wash ash and sediment into waterways.
"That ash and sediment load can impact fish and other biota that live in the waterways, it could also see the dissolved oxygen in the water reduce and as a result we could see fish deaths," Mr Reynolds said.
Mr Reynolds explained that as thousands of hectares of ground cover had been burnt in the Upper Murray, increased run off following rain events was likely.
"The run off could also pick up other contaminants from burnt buildings and the like," Mr Reynolds said.
He said the amount of rain and subsequent run off would determine how much contaminated water was released downstream from Hume Dam.
"I suspect much of the contamination that might run into Lake Hume will probably settle in the upstream reaches of the lake and potentially not even be seen in the releases made from Hume," Mr Reynolds said.
However, he explained the MDBA would have little choice but to continue to release water even if it did contain ash.
"We still have to meet the demand from downstream water users and we have very limited alternatives," Mr Reynolds said.
"There's no water in Menindee so the supply for South Australia really has to come from Hume Dam, so we will need to make those releases."
He said given the area's active firegrounds, the number of tributaries that supply Hume Dam and its extensive size, it would be very difficult to employ the tactics being undertaken by Water NSW at Warragamba Dam to protect Sydney's drinking water from ash.
"Water NSW have put silk curtains in the upstream reaches of Warragamba, we will consider whether or not something similar could be done at Hume, but I think the practicalities of doing that are pretty limited," Mr Reynolds said.
Murray catchment water users are advised to stay up to date with water quality information from their local water authorities.