About the document
This report is the product of the second year of monitoring and evaluation in the Lower Murray River under the Commonwealth Environmental Water Office’s Long Term Intervention Monitoring (LTIM) Project. The report evaluates the contribution of Commonwealth environmental water to environmental outcomes in 2015-16, complementing the first year of LTIM Project monitoring and evaluation work undertaken in 2014-15 and previous short term monitoring and evaluation work undertaken between 2010 and 2014.
The Lower Murray River LTIM Project identified a number of key environmental outcomes achieved through the use of environmental water in 2015-16, including:
- Environmental water reduced salinity levels in the Lower Murray Channel, Lower Lakes, Coorong and Murray Mouth. It also transported nutrients through the river system, and in doing so may have provided ‘food’ for aquatic plants and animals. Commonwealth environmental water provided 100 per cent of flows over the barrages between September 2015 and June 2016 into the Coorong.
- Environmental water use over successive years of lower flows has shown significant benefits for the system through the export of excess salt from the river, as well as through the reduction of the amount of salt imported into the Murray Mouth from the sea.
- Using environmental water to raise weir pools in the Lower Murray provided improved connections between the floodplain and the river, which may have provided more fish food. In years of relatively low flow, changes in weir pool levels in conjunction with environmental water use can confer ecological benefits between the river and floodplain, such as nutrient exchange and wetting of fringing vegetation.
- Due to the low flows, there was little spawning and no recruitment* of golden and silver perch in the Lower Murray. Compared to the previous year, the number and different types of small-bodied fish remained high, however, there was an increase in number of exotic goldfish and common carp.
- For the second consecutive year, small Murray cod were found in the Lower Murray, indicating successful recruitment*. The conditions which have supported this recruitment remain unclear.
*Recruitment describes a species’ (like native fish, frogs and turtles) survival through all life stages, from spawning, juvenile to adulthood. The Commonwealth Environmental Water Holder aims to create or support breeding events and recruitment so that over the long-term a species’ population features a range of ages (young to old).
The report is presented in three parts:
- An executive summary;
- A non-technical synthesis report; and
- A technical appendices which provide detailed methods, analyses and results for each indicator.
This report is the second of five to be produced for the Lower Murray River Selected Area under the LTIM Project, with monitoring and evaluation being undertaken from 2014-15 to 2018-19. The data and evaluation report from this project are being combined with those from six other LTIM Project Selected Areas within the Basin, as part of a Basin-scale evaluation of the contribution of Commonwealth environmental water to the environmental objectives of the Basin Plan being led by the Murray-Darling Freshwater Research Centre.
In addition to assisting the Office to demonstrate environmental outcomes, the LTIM Project is designed to allow adaptive management of the water holdings. As such, identified outcomes and limitations are used to inform environmental watering in future years leveraging the best available, contemporary scientific knowledge.