Document ID: chunk:federal_register_of_legislation:F2019L00106:body:0:p47
Version: federal_register_of_legislation:F2019L00106
Segment Type: other
Provision Reference: 
Character Range: 125345–128313

Lintermans et al., 2014). Consequently, 32 adult fish were translocated to Victorina Government hatchery facilities and then re-released into Hughes Creek when water quality had improved (Lintermans et al., 2014).
The exceptions are small populations of Macquarie perch below Cordeaux Dam in the Cordeaux River and the upper Murrumbidgee River in areas downstream of Tantangara Dam ('Cooma Gorge'). If flow regulation were to mimic natural flow regimes, while avoiding sudden, extreme flooding events, these populations of Macquarie perch would more than likely respond positively.
Studies suggest that any impounded water body over five metres in depth can undergo thermal stratification, except those reservoirs where average yearly inflow volume exceeds the reservoir volume by a factor of 10 or more (Harleman 1982). Warm water is less dense than cooler water, and therefore 'floats' above denser cooler water (Bayly & Williams 1973). Since most impoundments are only equipped with bottom release valves only cold water can be released downstream, causing 'cold water' or 'thermal pollution' (Koehn 2001; Ryan et al., 2001; Astles et al., 2003; Preece 2004; Sherman et al., 2007).
Regulation of flows through controlled release from storages, which is often the release of cold water, and water extraction have vastly changed the hydrology and thermal regimes of river systems, causing widespread degradation and are considered to be severely impacting upon native fish in the Murray-Darling Basin (Koehn & O'Connor 1990a; Faragher & Harris, 1994; Koehn et al., 1995; Gehrke et al., 1999; Koehn 2001; Phillips 2001; Astles et al., 2003; MDBC 2004). Cold water pollution has the effect of reducing annual temperature ranges, delaying the timing of summer temperature peaks, eliminating the natural rapid temperature rise in spring and also severely reducing the difference between annual maximum and minimum temperature (Lugg 1999; Ryan et al., 2001). In Lake Eildon, it was found that Macquarie perch required the water temperature to rise to 16.5°C before spawning could occur (Cadwallader & Rogan 1977), and it was considered that the colder water of the Reservoir and extent of flooding were severely impacting the species ability to reproduce in this catchment (Cadwallader 1978). Macquarie perch spawning was detected in the Yarra River at water temperatures of approximately 17°C (King & Mahoney 2009). A recent study showed a positive influence on spawning intensity in two riverine populations in King Parrot Creek and the Yarra River, with the greatest abundance of eggs recorded when mean daily water temperatures exceeded 18°C between late-October and early-December (Tonkin et al., 2016a). A laboratory study on the effect of temperature on <24 hour and one-week old Macquarie perch larvae found that <24 hour individuals were significantly affected by water temperatures below 12°C, while one-week old individuals were comparatively resilient (Raymond