This winter, GMW is undertaking critical maintenance across its network to ensure channels and infrastructure are properly maintained and safe ahead of the next irrigation season.
This includes a weed treatment program, which takes place during the irrigation shut down period between May and August each year. This winter GMW is treating hundreds of kilometres of channel, with more than 90 per cent of the program already complete.
GMW Water Delivery Services General Manager, Warren Blyth said submerged weeds affect water flow, promote silting and cause issues with automatic regulators, which can reduce the ability for GMW to deliver water to its customers.
“The irrigation shut down period allows the perfect opportunity for us to undertake a range of treatments which include de-watering channels and herbicide spraying or injections,” Mr Blyth said.
“The type of treatment often depends on the type and extent of the weed and the characteristics of the channel and our Water Delivery and Infrastructure Delivery Services teams work closely together to carefully plan out a targeted program each year.”
This winter, weed treatment programs are underway in all irrigation areas across the East, Central and West irrigation areas. Affected customers on these channels have been notified of the treatment and required withholding periods, meaning the channel water cannot be used for stock, horticulture and broad-acre crops for a specified time.
As GMW does not guarantee water supply during the winter period, customers have previously been advised to secure a winter water supply by filling their dams or tanks.
Mr Blyth said GMW have been researching and testing options to improve its weed treatment program, which this year includes the trial of a new chemical, Flumioxazin. It is being used to treat submersed aquatic weeds such as Hornwort, Ribbon weed and Egeria which choke the network.
“In diluted form, Flumioxazin has a very low toxicity to humans and animals,” Mr Blyth said.
“While GMW’s channel network is not a natural waterway intended for use as habitat for fish or other animals it is important for us to minimise impact to aquatic life and the environment.
Flumioxazin is being trialled at four sites in the Murray Valley Irrigation area this winter, and was used on a smaller scale last year. The results of this trial, including the efficacy on weed type, difference in application method and longevity on control will help determine how the chemical is used more broadly for future treatment programs.
Flumioxazin is being trialled under a permit with the Australian Pesticides and Veterinary Medicines Authority (APVMA).
For more information on maintenance works on our channel system visit: Planned maintenance and outages - Goulburn Murray Water (g-mwater.com.au)