Reservoir · Western Australia · Australia · BOM Water Data Online
Glen Mervyn
59.6% full
Capacity
2.1 hm³
Volume stored
1 hm³
River
McCallum Creek
Year completed
1969
Coordinates
33.498°S, 116.100°E
Last updated
2026-09-06
Current fill
59.6%vs 7 days ago
+1.5%gaining
vs 1 year ago
-4.9%year-over-year
7-day trend
→stable
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: 2026-09-06.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. -33.498, 116.100 · Open in Google Maps
About Glen Mervyn
As of September 6, 2026, Glen Mervyn is filled to 59.6% of its total capacity, holding roughly 1 hm³ of water out of a maximum 2 hm³. At this level the reservoir is within its normal operating range.
Over the most recent week on record the fill level has held broadly steady (+1.5 pts), and it is 4.9 points below its level on the same date a year earlier.
Across the readings we hold for Glen Mervyn — 1050 data points between September 11, 2023 and September 6, 2026 — the level has ranged from a low of 2.0% (April 27, 2024) to a high of 77.5% (October 17, 2025). On average the reservoir is fullest around October and at its lowest around May.
The dam at Glen Mervyn was completed in 1969. It is operated by BOM primarily for water supply. It lies within the McCallum Creek Basin basin at 33.498°S, 116.100°E.
Key facts
- Current fill level
- 59.6%
- Water stored
- 1 hm³
- Total capacity
- 2 hm³
- 7-day change
- ▲ 1.5 pts
- Year-on-year
- ▼ 4.9 pts
- Primary use
- Water supply
- River
- McCallum Creek
- River basin
- McCallum Creek Basin
- Year completed
- 1969
- Operator
- BOM
- Coordinates
- 33.498°S, 116.100°E
- Last updated
- September 6, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 6 Sep 2026 | 59.6% | 1 |
| 5 Sep 2026 | 59.5% | 1 |
| 4 Sep 2026 | 59.3% | 1 |
| 3 Sep 2026 | 59.1% | 1 |
| 2 Sep 2026 | 58.9% | 1 |
| 1 Sep 2026 | 58.6% | 1 |
| 31 Aug 2026 | 58.3% | 1 |
| 30 Aug 2026 | 58.1% | 1 |
| 29 Aug 2026 | 57.9% | 1 |
| 28 Aug 2026 | 57.7% | 1 |
| 27 Aug 2026 | 57.1% | 1 |
| 26 Aug 2026 | 56.6% | 1 |