Commonwealth Environmental Water Office Long-Term Intervention Monitoring Project Murrumbidgee River system Selected Area evaluation report, 2014-17

The Murrumbidgee River Long-Term Intervention Monitoring (LTIM) project is a collaborative project between Charles Sturt University, NSW Office of Environment and Heritage, Department of Primary Industries - Fisheries and the University of New South Wales (Centre for Ecosystem Science). Funding from the Commonwealth Environmental Water Office supports monitoring of the hydrological and ecological outcomes of watering actions in the river and wetlands of the Murrumbidgee for a five-year period. This report documents findings from the first three years of the LTIM project, from 2014 to 2017.The LTIM project focuses monitoring activities through the mid and lower Murrumbidgee River and floodplain, which is referred to in this report as the Murrumbidgee Selected Area. In this report the outcomes of Commonwealth environmental watering actions are evaluated in two sections: Riverine outcomes andWetland outcomes. The riverine sections focus on monitoring activities undertaken through a 545km stretch of River between Wagga Wagga and Carrathool, in 2016-17 additional evaluation of water quality was undertaken within the Murrumbidgee River between Carrathool and Balranald in response to Commonwealth Environmental watering actions aimed at mitigating hypoxic black water risk. The wetland section evaluates outcomes of Commonwealth environmental watering actions across three zones: the mid-Murrumbidgee which is a series of lagoons bordering the Murrumbidgee River between Narrandera and Carrathool; and the Nimmie-Caira and Redbank zones through the Lower Murrumbidgee floodplain (Lowbidgee).In 2016-17 the Commonwealth environmental water holder delivered 241,465 ML of environmental water as part of 13 watering actions targeting the main river channel,key floodplain and wetland habitats, and anabranches and creek lines through the Murrumbidgee. Environmental watering actions commenced in winter of 2016, when water was delivered to areas of the Lowbidgee floodplain to support floodplain habitat for the threatened southern bell frog and other floodplain dependant species.In early spring, widespread rainfall throughout the catchment produced significant unregulated river rises and extensive floodplain inundation through the midMurrumbidgee and Lowbidgee floodplains. All Commonwealth and State environmental watering actions were halted during this period, with environmental watering actions commencing during the flood recession in order to manage the risk 13 of hypoxic blackwater by managing the rate of flood recession. In addition to these in-channel flows, the Commonwealth Environmental Water Holder, in collaboration with NSW Office of Environment and Heritage, undertook five watering actions to support water bird breeding in the Lowbidgee floodplain which was initially triggered by unregulated floodplain inundation, but required additional watering to ensure that chicks survived to fledging.