Indicator: IW-23 Mapping of water temperature depression due to dam releases
Data
| Rank | Name | Height (m) | Capacity (ML) | Mean Depth (m) | Intake Depth (m) | Discharge (ML day –1) | Estimated length of river (km) subject to severe (>5°C peak depression) CWP |
|---|---|---|---|---|---|---|---|
| 1 | Blowering | 112 | 1 628 000 | 36.5 | 74 | 8 200 | 60 |
| 2 | Hume | 51 | 3 038 000 | 15 | 29 | 20 000 | 300 |
| 3 | Copeton | 113 | 1 364 000 | 32 | 69 | 3 600 | 300 |
| 4 | Burrinjuck | 93 | 1 026 000 | 18.7 | 42 | 5 200 | 400 |
| 5 | Burrendong | 76 | 1 190 000 | 16.5 | 37 | 4 000 | 400 |
| 6 | Wyangala | 85 | 1 220 000 | 23 | 50 | 1 700 | 400 |
| 7 | Keepit | 55 | 423 000 | 9.6 | 24 | 2 000 | 300 |
| 7 | Khancoban | 18 | 21 500 | 4.6 | 12 | 4 000 | 120 |
| 9 | Pindari | 85 | 312 000 | 29.7 | 11 | 1 000 |
Source: Preece, R 2004, Cold water pollution below dams in New South Wales, Department of Infrastructure, Planning and Natural Resources, Sydney, viewed 14 Oct 2005, http://www.dlwc.nsw.gov.au/care/water/cold_water_pollution.html.
Effect of cold water releases from Blowering Dam on the Tumut River
Source: Department of Environment and Conservation (NSW) 2003, NSW State of the Environment 2003: Chapter 5 Water, viewed 6 Apr 2005, http://www.epa.nsw.gov.au/soe/soe2003/chapter5
Water temperature of the Murrumbidgee River at Burrinjuck Dam
Source: Preece, R 2004, Cold water pollution below dams in New South Wales, Department of Infrastructure, Planning and Natural Resources, Sydney, viewed 14 Oct 2005, http://www.dlwc.nsw.gov.au/care/water/cold_water_pollution.html.
Experiments demonstrated that some native fish were affected by cold water pollution in the areas of growth, survival, distribution and activity. Consequences include reduced recruitment to adult populations, forced re-distribution of fish populations to less favourable habitats and general declines in fish populations because of decreased survival.
Source: Astles, K, Winstanley, R, Harris, J and Gehrke, P 2003, Regulated Rivers and Fisheries Restoration Project - Experimental study of the effects of cold water pollution on native fish, NSW Fisheries, Cronulla, NSW, viewed N/A, http://www.fisheries.nsw.gov.au/science/scientific_outputs/aqua-eco/317_experimental.
What the data mean
Cold water pollution occurs below large dams when cold water is released from the bottom of the dam into the river downstream, cooling the river water to 10 - 12°C; below its natural range. The size and scale of disturbance varies considerably between dams.
The effects of cold water pollution on organisms vary, depending on the species affected.
Data Limitations
National data are not available for this indicator. Long term trend data for dams where temperatures are routinely measured are also unavailable.
Issues for which this is an indicator and why
Inland Waters - Habitat scale influences - Water Quality (for surface and groundwater) - Thermal pollution
Mapping of water temperature is a direct measure of this pressure.
Further Information
- Cold Water Pollution (DF95) - September 2001
- Cold Water Pollution Below Dams in NSW
- Experimental study of the effects of cold water pollution on native fish (Astles et al. 2003)
Key
Links to another web site
Links to data in the DRS
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