A tale of two rivers
For almost 140 years, irrigation has dominated the lower Campaspe River. Smaller weirs up and down the waterway made way for the Eppalock dam almost 60 years ago.
Since then, the Campaspe has been two separate rivers, split in half by hundreds of thousands of tonnes of concrete.
River regulation for irrigation has turned the flow of the Campaspe downstream of Eppalock upside down, with higher flows in the warmer months and lower in the cooler months.
Native plants, fish and mammals that have evolved with the winter and spring flows over millions of years have struggled with the new normal.
“That is why water for the environment only flows through regulated systems,” North Central Catchment Management Authority (CMA) Environmental Water Reserve Project Manager Darren White said.
“It’s about helping the river cope with regulation, repairing any damage and ensuring it survives when it needs to and thrives when it can.”
Since early January, more than 45,000 megalitres of mostly irrigation water has flowed down the Campaspe River.
“That amount of water at that time of the year is not ideal, and well above the environmental recommendations of 6000ML.
“However, the Campaspe is a working river and an important one for irrigation communities. Water for the environment is a key part in helping the river deal with the pressures of irrigation.”
With the irrigation season closed until mid-August, a gentler flow will make its way down the Campaspe, beginning in the coming weeks and running until December.
A maximum of 200ML a day will flow downstream from the Eppalock dam, averaging two thirds less than the previous five months.
“Water for the environment is about the right amount of water at the right time,” Mr White said.
“It looks like a lot of fringing vegetation is stressed and we have to re-establish conditions for spring, as well as allow snags to breathe so they can provide perfect breeding grounds for waterbugs
“Vegetation such as this needs fluctuating water levels, and this flow will deliver those. We aren’t sure of the impact of the recent large irrigation flows on native fish yet, but this healthy flow will be closer to what they need.”
The Campaspe River is home to healthy populations of the nationally Critically Endangered silver perch, the Vulnerable Murray Darling rainbowfish, golden perch and the iconic Endangered Murray Cod.
“An important platypus population also lives in the Campaspe, and we are slowly building their numbers back up after the 2016 floods wiped out an entire generation,” Mr White said.
“In total, the amount of water of this flow will be about 10 per cent of what is in Lake Eppalock now, and just over five per cent of the lake’s total capacity.
“Winter and spring is when the river flows naturally. If it does, water will enter Eppalock, but without water for the environment, downstream flows will be minimal.”
The flow is part of the Victorian Government’s $222 million investment over the next four years to improve the health of waterways and catchments.
The flows are authorised by the Victorian Environmental Water Holder in line with its Seasonal Watering Plan 2017-18. The VEWH Seasonal Watering Plan 2017-18 is available for download from www.vewh.vic.gov.au, with regular watering updates posted on the North Central CMA website.