Case study 1: Murrumbidgee River system

In winter 2011 at a time of lower rainfalls, hundreds of wetlands along the Murrumbidgee River, from Gundagai through to the Murray River, benefited from the largest Commonwealth watering action to date. Over 161 gigalitres of water (including nearly 110 gigalitres of Commonwealth environmental water) was provided as river flows to benefit the Murray system as far downstream as the Lower Lakes. Despite good rainfall over the last nine months, the ecological response in parts of the Murrumbidgee had been limited. The watering action sought to address this by providing a good wetting through to spring for the river and many fringing wetlands. The watering action provided freshwater flows that contributed to:

• Maintaining ecological health and resilience—the water will support the survival of river red gums, black box and littoral zone seedlings that have germinated in response to the floods over the 2010–11 water year.
• Providing a pathway for nutrients to be supplied into the river—this will support the food chains of higher trophic species such as fish, frogs and waterbirds and help these species to build condition in preparation for spring breeding activities.
• Reconnecting wetlands and lagoons along the Murrumbidgee River and Yanco Creek system—water provided to the Murrumbidgee River will allow higher flows to enter the Yanco Creek system, including Yanco, Colombo, Forest and Billabong creeks. Flows will create additional habitat for wetland dependent species, allow for increased movement and contribute to creating suitable breeding habitat for frog species.
• Promoting natural riverine processes—environmental water generated Murrumbidgee River flows downstream of Burrinjuck Dam, contributing to healthy biofilms (collections of microorganisms that live on hard surfaces in the river channel), and also improving fish habitat.