Reservoir · Western Australia · Australia · BOM Water Data Online
Glen Mervyn
61.5% full
Capacity
2.1 hm³
Volume stored
1 hm³
River
McCallum Creek
Year completed
1969
Coordinates
33.498°S, 116.100°E
Last updated
2026-10-20
Current fill
61.5%vs 7 days ago
0.0 ppstable
vs 1 year ago
-15.7 ppyear-over-year
7-day trend
→stable
Drought context
Storage vs October average
94%of normal
61.5% full on 2026-10-20, against an average of 65.1% for October across 4 years of readings (-3.6 points).
Rain over the last three months · 11 October 2026
Moderately dry
In the three months to 11 October 2026 the area around Glen Mervyn 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 −1.40). 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: 2026-10-20.
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 33.498°S, 116.100°E · Open in Google Maps
About Glen Mervyn
As of October 20, 2026, Glen Mervyn is filled to 61.5% of its total capacity, holding 1.26 hm³ of water out of a maximum 2.1 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 (+0.0 pp), and it is 15.7 points below its level on the same date a year earlier.
Across the readings we hold for Glen Mervyn — 1047 data points between October 28, 2023 and October 20, 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
- 61.5% of total capacity
- Water stored
- 1.26 hm³
- Total capacity
- 2.1 hm³
- 7-day change
- No change
- Year-on-year
- ▼ 15.7 pp
- 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
- October 20, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 20 Oct 2026 | 61.5% | 1.26 |
| 19 Oct 2026 | 61.4% | 1.26 |
| 18 Oct 2026 | 61.5% | 1.26 |
| 17 Oct 2026 | 61.7% | 1.27 |
| 16 Oct 2026 | 61.9% | 1.27 |
| 15 Oct 2026 | 61.8% | 1.27 |
| 14 Oct 2026 | 61.7% | 1.27 |
| 13 Oct 2026 | 61.5% | 1.26 |
| 12 Oct 2026 | 61.2% | 1.25 |
| 11 Oct 2026 | 60.8% | 1.25 |
| 10 Oct 2026 | 60.4% | 1.24 |
| 9 Oct 2026 | 60.2% | 1.23 |