Commonwealth Long-Term Intervention Monitoring Project: Stage 1 Mid-Term Review and Evaluation

Lower Murray

During 2015-16, approximately 814 GL of CEW was delivered to the LMR from 1 July to 30 November 2015, and from 2 January to 30 June 2016. This included 15.8 GL of CEW used for wetlands and weir pool raising (WPR) within South Australia, with the remaining ~798 GL flowing through the main channel. Note that in July and August 2015, the CEW consisted largely of return flows from the Barmah–Millewa Forest and flow pulse events in the Goulburn River.

Findings: This was the only evaluation report that included objectives, KEQ and associated hypothesis – well defined/presented. No consideration of Basin-scale evaluation – states MDFRC to address Basin-scale evaluation. Included results for DEWNR objectives for the LTWP. No reference to Basin Plan Environmental Watering Plan objectives or expected outcomes from watering actions (this is the reason some of the ratings are yellow – can’t say if achieved). Only short term 1 year outcomes were evaluated, but each KEQ addressed/answered in terms of contribution by CEW.

Ye et al. (2017) is a useful report that provides a good discussion and summary of the 2015-16 monitoring program and key findings. The report would be improved with the inclusion of a clear summary of what monitoring was undertaken in 2015-16, covering which of the environmental flow events were monitored, why and what indicators in the overview/summary report.

Table . Assessment of progress towards expected outcomes and Area-scale LTIM KEQ for the Lower Murray.

Indicator	Expected outcomes	Area-scale LTIM KEQ	Rating	Justification
Hydrology (channel) (Cat I)	Not specified	None specified		Doesn’t directly address any specific KEQ, but provides fundamental information for analysis and evaluation of all other indicators (Ye et al. 2017). Expectation that Cat I indicators are evaluated at the Basin-scale by MDFRC.
Stream Metabolism(Cat I)		What did CEW contribute to: patterns and rates of decomposition? patterns and rates of primary productivity? dissolved oxygen levels?		There were enhanced gross primary production and respiration rates associated with WPR in Weir Pool 5 and return flows from Chowilla, both of which were supported by CEW. Integrated ecosystem net production was near zero, indicating that organic material was derived from aquatic production with little enhancement from external supplies that could have further increased food supplies. Oxygen concentrations did not fall below acceptable levels (>50% saturation) (Ye et al. 2017, Table 1)
Fish (channel) (Cat I)		None specified		There are no KEQ for this indicator at the SA scale; however, fish monitoring data are consolidated to evaluate a number of fish targets of DEWNR’s LTWP (Ye et al. 2017).
Hydrological Regime (Cat III)		What did CEW contribute to: Hydraulic diversity within weir pools? Variability in water levels within weir pools?		Some increase in velocities in winter and spring with CEW. Some variability achieved in weir pools – can’t really state if on track as no expected outcomes stated, but suspect this indicator is probably okay.
Matter Transport(Cat III)		What did CEW contribute to: salinity levels and transport? nutrient concentrations and transport?		Increased salt transport through and out of system, only minor changes in concentrations. Also some transport of nutrients.
		concentrations and transport of phytoplankton?		No impact on concentrations, but transport did occur
		ecosystem function?		Increased exchange of nutrients and phytoplankton between critical habitats possibly influenced ecosystem function – but early days.
		water quality to support aquatic biota and normal biogeochemical processes?		Reduced salinity concentrations in particular may have improved conditions in the Lower Lakes and Murray Mouth (Ye et al. 2017).
Microinvertebrates (Cat III)		What did CEW contribute: to microinvertebrate diversity?		Peak diversity matched peaks in river discharge and CEW. Most taxa were transported taxa from floodplain or riparian sources (e.g. Chowilla) Ye et al. (2017).
		via upstream connectivity to microinvertebrate communities of the LMR Selected Area?		Likely to be achieved – some indication of taxa being transported from upstream, but could also be from lateral connections (Ye et al. 2017).
		to the timing and presence of key species in relation to diet of large-bodied native fish larvae (e.g. golden perch)?		Relationship could not be determined.
		to microinvertebrate abundance (density)?		Flow including CEW contributed to changes in density of microinvertebrates. Reduced flows had reduced densities (Ye et al. 2017)
Fish Spawning and Recruitment (Cat III)		What did CEW contribute to: reproduction of golden perch and silver perch?		Limited spawning and negligible recruitment (to YOY, age 0+) of golden perch and silver perch (Ye et al. 2017).