"You can just imagine leaving a fish in your kitchen to rot with all the doors shut and no air conditioner, and we've got millions of them."
The temperature in Menindee was expected to reach 41C on Saturday.
He added that locals in the regional town rely on the Darling-Baaka for water supplies, "we use the river water for washing and showering in so people won't be able to use that water for those basic needs again," he said.
"Over time those people won't be able to access that water for domestic use which is just shameful".