TRÊS MARIAS
Minas Gerais · SAO FRANCISCO
Useful capacity
15,278 hm³
Coordinates
18.218°S, 45.262°W
Operator
ONS
71.5% of useful capacity
Current fill
71.5%of useful capacity
vs 7 days ago
-1.3 pplosing
vs 1 year ago
+14.7 ppyear-over-year
7-day trend
↓falling
Drought context
Storage vs October average
109%of normal
71.5% full on 2026-10-26, against an average of 65.3% for October across 2 years of readings (+6.2 points).
Rain over the last three months · 11 October 2026
Near normal
In the three months to 11 October 2026 the area around TRÊS MARIAS had rain close to normal for the season. Rainfall compared with the long-run record for the same season at this point (Copernicus Global Drought Observatory, SPI-3 index +0.60). Rain, not storage. Brazil drought figures →
Catchment Weather
Past 30 days + 14-day forecast · Open-Meteo
Technical specifications
| Total capacity | 19,528 hm³ |
| Usable capacity | 15,278 hm³ |
| Primary use | Hydroelectric |
| Operator | ONS |
| River | SÃO FRANCISCO |
| Province | Minas Gerais |
| River basin | SAO FRANCISCO |
Satellite imagery: Esri, Maxar, Earthstar Geographics. Map: Esri, HERE, Garmin, © OpenStreetMap contributors. 18.218°S, 45.262°W · Open in Google Maps
About TRÊS MARIAS
As of October 26, 2026, TRÊS MARIAS is at 71.5% of useful capacity, holding 10,928 hm³ of 15,278 hm³. Of the 19,528 hm³ total capacity, that is 56.0%. At this level the reservoir is within its normal operating range.
Over the most recent week on record the fill level has fallen by 1.3 percentage points, and it is 14.7 points above its level on the same date a year earlier.
Across the readings we hold for TRÊS MARIAS — 65 data points between October 26, 2025 and October 26, 2026 — the level has ranged from a low of 51.8% (December 12, 2025) to a high of 102.3% (April 17, 2026). On average the reservoir is fullest around April and at its lowest around December.
It is operated by ONS primarily for hydroelectric power. It lies within the SAO FRANCISCO basin at 18.218°S, 45.262°W.
Key facts
- Current fill level
- 71.5% of useful capacity
- Water stored
- 10,928 hm³
- Total capacity
- 19,528 hm³
- Usable capacity
- 15,278 hm³
- 7-day change
- ▼ 1.3 pp
- Year-on-year
- ▲ 14.7 pp
- Primary use
- Hydroelectric power
- River
- SÃO FRANCISCO
- River basin
- SAO FRANCISCO
- Operator
- ONS
- Coordinates
- 18.218°S, 45.262°W
- Last updated
- October 26, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 26 Oct 2026 | 71.5% | 10,928 |
| 25 Oct 2026 | 71.6% | 10,945 |
| 24 Oct 2026 | 71.6% | 10,945 |
| 23 Oct 2026 | 71.6% | 10,945 |
| 22 Oct 2026 | 71.9% | 10,979 |
| 21 Oct 2026 | 72.0% | 10,996 |
| 20 Oct 2026 | 72.4% | 11,055 |
| 19 Oct 2026 | 72.8% | 11,121 |
| 18 Oct 2026 | 73.4% | 11,214 |
| 17 Oct 2026 | 74.1% | 11,315 |
| 16 Oct 2026 | 74.6% | 11,391 |
| 15 Oct 2026 | 75.0% | 11,451 |