Murray and Lower Darling Environmental Water Advisory Group communique

On 20 June 2023, the Murray and Lower Darling Environmental Water Advisory Group (EWAG) met online to discuss priorities for the 2023–24 water year.

Catchment conditions, forecast and operations update

The forecast is consistent across the basin, with the outlook indicating drier than median conditions in the coming months.

Water storages are effectively full, and air space is being managed with Dartmouth and Hume dams releases. Rainfall over the irrigation areas has impacted releases, and significant inflows into the Murray from the Great Darling Anabranch, Kiewa, and Ovens rivers have boosted flows.

Fish survey results

The Arthur Rylah Institute provided a summary of its fish survey work, including the impacts of flooding and blackwater. While blackwater contributed to fish deaths, the events also occurred because of overbank flows and water velocity.

There has been a large increase in carp numbers while other species, including Murray cod, golden perch, and trout cod numbers are down, particularly in areas of the river affected by hypoxic (low oxygen) blackwater. The number of small-bodied native fish has also declined.

Environmental flows have been used to maintain water quality in the system, but this approach has limitations. In the longer term, addressing flow constraints can achieve better environmental outcomes, including water quality and native fish.

An update on the Arthur Rylah Institute's fish research can be found on the Arthur Rylah Institute for Environmental Research site.

Site manager reports and watering plans for 2023–24

As part of the site manager report:

• Water managers are planning to target wetlands above Yarrawonga that connect only occasionally with the river channel because of flow constraints. If the planned event goes ahead, other areas of the Murray River system could benefit. There are also ongoing discussions with Traditional Owners and department threatened species officers to consider whether environmental flows could be delivered to wetlands around Howlong and Corowa. These flows would support species such as the Sloane's froglet and small-bodied wetland specialist fish, including the southern pygmy perch.
• The Niemur River offtake regulator is a major barrier to flow and fish passage in the Edward–Wakool River system, so improved flow using water for the environment will allow this structure to be opened more frequently and improve fish passage between the Niemur and Edward rivers.