TRÊS MARIAS
Minas Gerais · SAO FRANCISCO
Capacity
19,528 hm³
Coordinates
-18.218°N, 45.262°W
Operator
ONS
84.2% full
Current fill
84.2%vs 7 days ago
-1.3%losing
vs 1 year ago
N/A7-day trend
→stable
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, -45.262 · Open in Google Maps
About TRÊS MARIAS
As of September 9, 2026, TRÊS MARIAS is filled to 84.2% of its total capacity, holding roughly 12,864 hm³ of water out of a maximum 19,528 hm³. At this level the reservoir is high. Of that total, about 15,278 hm³ is usable (live) storage.
Over the most recent week on record the fill level has held broadly steady (-1.3 pts).
Across the readings we hold for TRÊS MARIAS — 52 data points between September 26, 2025 and September 9, 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
- 84.2%
- Water stored
- 12,864 hm³
- Total capacity
- 19,528 hm³
- Usable capacity
- 15,278 hm³
- 7-day change
- ▼ 1.3 pts
- Primary use
- Hydroelectric power
- River
- SÃO FRANCISCO
- River basin
- SAO FRANCISCO
- Operator
- ONS
- Coordinates
- 18.218°S, 45.262°W
- Last updated
- September 9, 2026
Recent readings
| Date | Fill level | Volume (hm³) |
|---|---|---|
| 9 Sep 2026 | 84.2% | 12,864 |
| 4 Sep 2026 | 85.5% | 13,060 |
| 28 Aug 2026 | 87.1% | 13,301 |
| 21 Aug 2026 | 88.4% | 13,503 |
| 14 Aug 2026 | 89.7% | 13,698 |
| 7 Aug 2026 | 90.8% | 13,877 |
| 31 Jul 2026 | 91.9% | 14,047 |
| 24 Jul 2026 | 93.0% | 14,216 |
| 17 Jul 2026 | 93.8% | 14,338 |
| 10 Jul 2026 | 94.7% | 14,470 |
| 3 Jul 2026 | 95.3% | 14,555 |
| 26 Jun 2026 | 95.8% | 14,635 |