This is the first year the upper Murray wetlands have been included in the VEWH’s seasonal watering plan and the first time water for the environment is planned to be delivered to the Ryans Lagoon wetland complex. The Ryans Lagoon wetland complex is a network of wetlands positioned downstream of the Lake Hume water storage and upstream of the Kiewa River confluence with the Murray River.
Flows into the complex are mainly influenced by regulated releases from Lake Hume, which travel via Ryans Creek, an anabranch of the Murray River. The complex begins to fill from Ryans Floodway when flows in the Murray River exceed 23,000 ML per day, but flows above 26,000 ML per day for extended periods are needed to completely fill both lagoons. High unregulated flows that move across the Kiewa River floodplain during wet conditions can also inundate the site. Since 2014, the maximum regulated flow from Lake Hume has reduced from 25,000 ML per day to less than 20,000 ML per day. These changes have greatly reduced the frequency of watering at Ryans Lagoon, which currently only fills if large, unregulated flows are released from Lake Hume or the reservoir spills.
Temporary pumps will be used to deliver water for the environment to restore the ecological health of the complex by providing a wetting and drying regime that is closer to the natural flow regime that existed before the regulation of the Murray River. Water can be pumped into Ryans Lagoon from the Ryans Lagoon floodway, which carries water when the flow in the Murray River exceeds 8,000 ML per day.
North East CMA is investigating options to improve watering regimes at other wetlands along the upper Murray floodplain.