Reservoir · Tasmania · Australia · BOM Water Data Online
Lake Cethana
12.7% full
Capacity
112.2 hm³
Volume stored
14 hm³
River
Forth River
Year completed
1971
Coordinates
41.509°S, 146.133°E
Last updated
2026-09-07
Current fill
12.7%vs 7 days ago
+7.4%gaining
vs 1 year ago
+4.0%year-over-year
7-day trend
↑rising
Data source: Bureau of Meteorology — Water Data Online (KiWIS) — daily mean storage volume, quality-controlled. Capacity from the BOM Water Storages ArcGIS layer (total design capacity in ML). Last reading: 2026-09-07.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. -41.509, 146.133 · Open in Google Maps
About Lake Cethana
As of September 7, 2026, Lake Cethana is filled to 12.7% of its total capacity, holding roughly 14 hm³ of water out of a maximum 112 hm³. At this level the reservoir is critically low. Of that total, about 48 hm³ is usable (live) storage.
Over the most recent week on record the fill level has risen by 7.4 percentage points, and it is 4.0 points above its level on the same date a year earlier.
Across the readings we hold for Lake Cethana — 1090 data points between September 14, 2023 and September 7, 2026 — the level has ranged from a low of 0.4% (July 23, 2026) to a high of 29.7% (September 2, 2024). On average the reservoir is fullest around September and at its lowest around June.
The dam at Lake Cethana was completed in 1971. It is operated by BOM primarily for water supply. It lies within the Forth River Basin basin at 41.509°S, 146.133°E.
Key facts
- Current fill level
- 12.7%
- Water stored
- 14 hm³
- Total capacity
- 112 hm³
- Usable capacity
- 48 hm³
- 7-day change
- ▲ 7.4 pts
- Year-on-year
- ▲ 4.0 pts
- Primary use
- Water supply
- River
- Forth River
- River basin
- Forth River Basin
- Year completed
- 1971
- Operator
- BOM
- Coordinates
- 41.509°S, 146.133°E
- Last updated
- September 7, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 7 Sep 2026 | 12.7% | 14 |
| 6 Sep 2026 | 10.7% | 12 |
| 5 Sep 2026 | 5.3% | 6 |
| 4 Sep 2026 | 4.4% | 5 |
| 3 Sep 2026 | 4.1% | 5 |
| 2 Sep 2026 | 3.8% | 4 |
| 1 Sep 2026 | 4.5% | 5 |
| 31 Aug 2026 | 5.3% | 6 |
| 30 Aug 2026 | 8.2% | 9 |
| 29 Aug 2026 | 8.8% | 10 |
| 28 Aug 2026 | 9.7% | 11 |
| 27 Aug 2026 | 9.7% | 11 |