Reservoir · Tasmania · Australia · BOM Water Data Online
Lake Cethana
19.7% full
Capacity
112.2 hm³
Volume stored
22 hm³
River
Forth River
Year completed
1971
Coordinates
41.509°S, 146.133°E
Last updated
2026-10-27
Current fill
19.7%vs 7 days ago
+0.4 ppgaining
vs 1 year ago
+4.8 ppyear-over-year
7-day trend
→stable
Drought context
Storage vs October average
122%of normal
19.7% full on 2026-10-27, against an average of 16.2% for October across 4 years of readings (+3.5 points).
Rain over the last three months · 11 October 2026
Moderately dry
In the three months to 11 October 2026 the area around Lake Cethana had well below normal rain, a shortfall seen about one year in six. Rainfall compared with the long-run record for the same season at this point (Copernicus Global Drought Observatory, SPI-3 index −1.22). Rain, not storage. Australia drought figures →
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: 2026-10-27.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 41.509°S, 146.133°E · Open in Google Maps
About Lake Cethana
As of October 27, 2026, Lake Cethana is filled to 19.7% of its total capacity, holding 22.14 hm³ of water out of a maximum 112.2 hm³. At this level the reservoir is critically low. Of that total, 48.3 hm³ is usable (live) storage.
Over the most recent week on record the fill level has held broadly steady (+0.4 pp), and it is 4.8 points above its level on the same date a year earlier.
Across the readings we hold for Lake Cethana — 1094 data points between October 30, 2023 and October 27, 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 October 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
- 19.7% of total capacity
- Water stored
- 22.14 hm³
- Total capacity
- 112.2 hm³
- Usable capacity
- 48.3 hm³
- 7-day change
- ▲ 0.4 pp
- Year-on-year
- ▲ 4.8 pp
- 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
- October 27, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 27 Oct 2026 | 19.7% | 22.14 |
| 26 Oct 2026 | 19.2% | 21.51 |
| 25 Oct 2026 | 19.4% | 21.74 |
| 24 Oct 2026 | 20.0% | 22.43 |
| 23 Oct 2026 | 19.8% | 22.24 |
| 22 Oct 2026 | 19.7% | 22.11 |
| 21 Oct 2026 | 19.3% | 21.7 |
| 20 Oct 2026 | 19.3% | 21.69 |
| 19 Oct 2026 | 19.5% | 21.89 |
| 18 Oct 2026 | 19.9% | 22.32 |
| 17 Oct 2026 | 20.4% | 22.93 |
| 16 Oct 2026 | 20.8% | 23.39 |