Science and nature combine to cancel flow
01 September 2016
Science and Mother Nature have combined forces ensuring there is no need for August's scheduled environmental water release down the Campaspe River. Rainfall in late July and early August fell at the same time the 50ML-a-day winter low flow was heading down the river.
The combination of the two resulted in enough water going down the river to meet the environmental objectives of a planned 4,700 ML winter fresh, due for late August.
"The August flow is required predominantly to trigger platypuses to build their burrows up high so their babies don't drown in a high flow, which is common in spring," North Central CMA Program Delivery Executive Manager Tim Shanahan said.
"Water is also required to help flush organic matter from the bank into the streams, to help prevent a toxic blackwater event during a summer high flow.
"Our monitoring has revealed the natural inflows below Lake Eppalock in the past month, combined with our 50ML-a-day winter low flow, have helped meet these requirements."
With one eye on reduced inflows from climate change, the proliferation of farm dams above Lake Eppalock, and a tough 20 years for the entire system, Mr Shanahan said it was more prudent to leave the water in the lake for possible use later on.
"In January we cancelled a planned flow when localised summer rain fell in the lower Campaspe catchment," he said.
"These cancellations show every decision we make about flows is based on science, data and the conditions at the time.
"However, this decision was touch and go because the flows below Lake Eppalock were small compared to the strong flows above the dam.
"We saw minor flood levels in the Campaspe River above Lake Eppalock this winter, but nowhere near that downstream, which shows the impact a dam can have on natural flows and the fish and platypus in the river.
"Environmental flows are needed because of the impact of the dam on the river. There would be no need for environmental flows if the dam wasn't there.
"This flow was one of two planned before the end of the year as part of the Victorian Environmental Water Holder's Seasonal Watering Plan 2016-17. We will make a decision about future flows the same way we have with this flow – based on science, data and the conditions at the time."
Communications Officer, North Central CMA
PO Box 18, Huntly VIC 3551
03 5448 7124