Environmental Flows From the Thomson Dam
Continuous releases are made from Thomson Reservoir to simultaneously satisfy minimum environmental flow requirements in the Thomson River at three locations downstream of the dam:
- immediately downstream of the dam;
- 11 km downstream of the dam at the Narrows and;
- 23 km downstream of the dam at Coopers Creek.
The minimum environmental flows shown in the table below are specified in the Environmental Bulk Entitlement for the Thomson River.
The bulk entitlement for the Thomson River Environment also allocates to the environment 10,000 ML of inflow to be held in the Thomson Reservoir for release to the waterway at a time that would achieve optimal river health.
The Thomson River Environmental Bulk Entitlement is managed by the West Gippsland Catchment Management Authority on behalf of the Minister for Environment.
Environmental flows (above minimum levels) are scheduled to be released into the Thomson River on behalf of Western Gippsland Catchment Management Authority between April and June 2012. Visit Western Gippsland Catchment Management Authority website for more information.
Minimum daily flow requirements downstream of Thomson Reservoir
| Month | Below Dam | Narrows | Coopers Ck |
|---|---|---|---|
| Jan | 75 ML/d | 120 ML/d | 200 ML/d |
| Feb | 75 ML/d | 120 ML/d | 180 ML/d |
| Mar | 25 ML/d | 80 ML/d | 155 ML/d |
| Apr | 25 ML/d | 80 ML/d | 155 ML/d |
| May | 25 ML/d | 80 ML/d | 150 ML/d |
| Jun | 25 ML/d | 80 ML/d | 150 ML/d |
| Jul | 25 ML/d | 80 ML/d | 216 ML/d |
| Aug | 25 ML/d | 80 ML/d | 238 ML/d |
| Sep | 25 ML/d | 80 ML/d | 245 ML/d |
| Oct | 25 ML/d | 80 ML/d | 225 ML/d |
| Nov | 75 ML/d | 120 ML/d | 205 ML/d |
| Dec | 75 ML/d | 120 ML/d | 200 ML/d |
Thomson Reservoir flows and releases since filling began
| Calendar Year | Inflows to Thomson Reservoir (ML) |
Transfers from Thomson to Upper Yarra Reservoir (ML) |
Irrigation Releases from Thomson Reservoir Under Entitlements (ML) |
Total Downstream Releases from Thomson Reservoir¹ (ML) |
|---|---|---|---|---|
| 1984 | 219,000 | 16,500 | 0 | 44,500 |
| 1985 | 240,500 | 500 | 0 | 32,000 |
| 1986 | 236,500 | 0 | 0 | 32,500 |
| 1987 | 187,500 | 37,000 | 0 | 34,000 |
| 1988 | 205,000 | 90,500 | 8,000 | 42,500 |
| 1989 | 245,500 | 0 | 2,500 | 43,500 |
| 1990 | 310,000 | 71,000 | 6,500 | 143,000 |
| 1991 | 273,500 | 85,500 | 0 | 176,000 |
| 1992 | 319,000 | 45,000 | 0 | 238,500 |
| 1993 | 275,000 | 70,500 | 0 | 231,500 |
| 1994 | 206,000 | 211,000 | 2,500 | 144,000 |
| 1995 | 278,500 | 81,000 | 3,500 | 143,500 |
| 1996 | 309,500 | 13,500 | 0 | 195,000 |
| 1997 | 93,500 | 254,500 | 22,500 | 172,500 |
| 1998 | 182,000 | 181,500 | 25,500 | 75,000 |
| 1999 | 125,500 | 194,500 | 1,000 | 56,000 |
| 2000 | 228,000 | 96,000 | 23,500 | 74,000 |
| 2001 | 175,500 | 135,000 | 7,500 | 51,000 |
| 2002 | 139,500 | 198,500 | 4,500 | 46,500 |
| 2003 | 210,500 | 161,000 | 3,500 | 46,000 |
| 2004 | 179,500 | 67,000 | 4,000 | 50,000 |
| 2005 | 152,000 | 138,000 | 3,000 | 53,000 |
| 2006 | 73,500 | 214,000 | 12,000 | 84,000 |
| 2007 | 179,000 | 96,000 | 12,000 | 52,000 |
| 2008 | 129,000 | 161,000 | 5,000 | 49,000 |
| 2009 | 153,500 | 90,000 | 5,000 | 50,000 |
| 2010 | 210,500 | 2,500 | 1,000 | 44,500 |
¹ Including spills plus environmental, SRW and hydro releases
** All figures rounded to nearest 500 ML
Note the impact of the current drought as flows from the Thomson decrease after it received approximately half its average rainfall in December 1996 and continued to receive minimal rainfall during subsequent years.