Document ID: chunk:federal_register_of_legislation:F2024C00760:reg:24:p26
Version: federal_register_of_legislation:F2024C00760
Segment Type: reg
Provision Reference: reg 24 (pt 26/36)
Character Range: 376976–379944

in the Macquarie Marshes have been reduced relative to without‑development conditions (Kingsford & Thomas 1995; Kingsford & Johnson 1998).
    22. Through the widespread drought conditions over the decade to 2010 the average annual stream flow at the Murray Mouth was particularly low. This resulted in the siltation of the Murray Mouth channel and the extreme hypersalinisation of the South Lagoon, where salinity reached more than four times that of seawater. Changes to the water regime of the River Murray have also been linked to a decline in abundance of a number of fish and waterbird species in the Coorong (Brookes et al. 2009).
    23. Low levels of flow during the recent drought conditions led to significant water quality problems (for example, blue‑green algal blooms; blackwater events in flushes after dry periods). While these are natural events, they have been increasing in intensity due to the changes in flow patterns in many rivers, particularly in the south. Small to medium floods, which normally would flush through floodplains quite regularly, are now contained and regulated.
    24. The health of riparian and wetland vegetation, which plays a key part in riverine ecology, has declined. Many areas remain under significant pressure from the combined effects of human activity and the recent drought. For example, in 2003, 80% of remaining river red gums on the River Murray floodplain in South Australia were stressed to some degree, and 20–30% were severely stressed. In the Macquarie Marshes, over half the river red gum forest and woodland had more than 40% dead canopy, and over 40% had more than 80% dead canopy (Bowen & Simpson 2009).
    25. The quality of groundwater resources in the Murray‑Darling Basin varies naturally from fresh through brackish to highly saline (in some areas exceeding the salinity of sea water). Most of the Basin's groundwater resources are relatively unchanged from without‑development conditions. However, significant changes have occurred in groundwater resources in some locations, including where large aquifers in areas of intensive irrigation development have been heavily used over the past 30 to 40 years. The condition of groundwater resources in the Basin, compared with their condition before land clearing and development for consumptive purposes, relates to the decline in groundwater levels (and pressure in confined systems) and the raising of groundwater levels because of increased recharge caused by local irrigation drainage or greater rainfall infiltration following land clearing.
Uses of Basin water resources
    26. The water resources of the Murray‑Darling Basin are used in agriculture, non‑agricultural industry, meeting critical human water needs and normal domestic requirements, for recreational and cultural purposes, and in maintaining freshwater ecosystems.
    27. Basin water resources are used both to irrigate food, fibre and pasture crops, and in dryland agriculture