Banks, plants and native fish respond to environmental flows

Monitoring during summer 2014 and autumn 2015 found environmental flows during those seasons had triggered golden perch spawning and encouraged bank-stabilising plant growth.

Testing bank condition

Environmental water is water set aside to improve or maintain the health of rivers, floodplains and wetlands and the plants and animals that depend on them. 

Environmental water deliveries in 2014/15 to the lower Goulburn River focused on increasing base flows from 250ML/day to at least 500ML/day (river height of 2.5m at Shepparton) throughout the year to increase food and shelter for native fish and water bugs.

Additional “freshes’’ (pulses of higher river flow) were delivered in spring, autumn and winter to provide cues for native fish breeding and passage, maintain water quality and support plant growth on river banks. Goulburn Broken Catchment Management Authority (CMA) Environmental Water Manager Simon Casanelia said the data, collected as part of the Commonwealth Environmental Water Holder’s Lower Goulburn River Long-Term Intervention Monitoring Project, confirmed environmental water was improving river health.

“The scientists involved in the monitoring program confirmed that the environmental water delivered during spring played an important role in triggering fish spawning, particularly golden perch,” Mr Casanelia said.

“In fact, the planned spring 2014 flow pulse encouraged golden perch spawning in numbers not previously seen, other than following the 2010 floods.”

Monitoring also found increases in the number of some types of water bugs (and other insects) after the spring freshes and that flood-tolerant plants were re-establishing on the river bank. 

“Water bugs provide food for fish, birds and other wildlife and good flood-tolerant bank vegetation stabilises banks during natural floods and heavy rainfall,” he said. 

"Based on early bank condition data collected during January to April 2015, managed environmental flows in summer/autumn do not appear to cause erosion above and beyond that resulting from the rises and falls of water levels due to water releases from dams and weirs to supply communities and irrigators. There were some initial observations that the deposits of mud following freshes have encouraged plant growth, again helping with bank stability.  

“While we are only one year in to this five-year monitoring program, it would appear environmental water delivered to date to improve the health of the Goulburn River, is achieving its goals.”

Information collected during monitoring will help inform the timing and size of future flows along the Lower Goulburn River.

“For example, we may consider slightly earlier spring environmental water freshes to give plants more time to get better established on the banks before the hot dry weather really sets in; and we’re still gathering evidence about golden perch breeding,” Mr Casanelia said.

“We know they spawn in the Goulburn River but we believe the eggs and larvae may flow to the Murray where they develop into adults before returning to the Goulburn. Future challenges including providing the right flow and habitat conditions to encourage juvenile and adult golden perch to return to the Goulburn River.”

The CEWH’s Long-Term Intervention Monitoring Project in the Goulburn River is a collaboration between Goulburn Broken CMA, University of Melbourne, the Arthur Rylah Institute (Department of Environment, Land, Water and Planning), Monash University, Streamology, Goulburn Valley Water, and Jacobs.

More information about monitoring in the Goulburn River, including You Tube clips and fact sheets, is available here.

The full 2014-15 Goulburn River Monitoring and Evaluation Report is available here.