Merrimack River below Concord River at Lowell, MA
USGS Site No: 01100000 • Merrimack River • Middlesex County, MA
Merrimack River below Concord River at Lowell, MA on the Merrimack River is currently at 7,160 cfs (Normal — 66th percentile for this date) . Gage height: 44.00 ft.
Reading from
Historical Percentile Comparison
Today's discharge compared to the long-term record for June 11 at this station. Percentile rank shows what fraction of historical years had lower flow on this date.
| Percentile | Label | CFS Threshold | Today's Flow |
|---|---|---|---|
| 10th | Very Low threshold | 2,450 | |
| 25th | Low threshold | 3,550 | |
| 50th (Median) | Normal (median) | 4,950 | |
| 75th | High threshold | 8,400 | Today: 7,160 cfs |
| 95th | Very High threshold | 20,400 |
30-Day Hydrograph
Recent discharge plotted against the historical 10th–95th percentile envelope for the same calendar days. Source: USGS daily values + long-term statistics.
30-Day Flow History
| Date | Discharge (CFS) | Gage Ht (ft) |
|---|---|---|
| May 28, 2026 | 8,890 | — |
| May 27, 2026 | 10,200 | — |
| May 26, 2026 | 9,290 | — |
| May 25, 2026 | 7,120 | — |
| May 24, 2026 | 6,420 | — |
| May 23, 2026 | 6,900 | — |
| May 22, 2026 | 7,860 | — |
| May 21, 2026 | 9,340 | — |
| May 20, 2026 | 11,600 | — |
| May 19, 2026 | 15,200 | — |
| May 18, 2026 | 21,000 | — |
| May 17, 2026 | 25,500 | — |
| May 16, 2026 | 22,600 | — |
| May 15, 2026 | 11,100 | — |
| Apr 21, 2026 | 11,900 | — |
| Apr 20, 2026 | 11,400 | — |
| Apr 19, 2026 | 13,200 | — |
| Apr 18, 2026 | 13,700 | — |
| Apr 17, 2026 | 12,700 | — |
| Apr 16, 2026 | 12,100 | — |
| Apr 15, 2026 | 9,610 | — |
| Apr 14, 2026 | 8,330 | — |
| Apr 13, 2026 | 8,640 | — |
| Apr 12, 2026 | 8,830 | — |
| Apr 11, 2026 | 9,530 | — |
| Apr 10, 2026 | 10,700 | — |
| Apr 9, 2026 | 11,800 | — |
| Apr 8, 2026 | 13,300 | — |
| Apr 7, 2026 | 15,300 | — |
| Apr 6, 2026 | 16,000 | — |
Station Information
- USGS Site No
- 01100000
- State
- MA
- County
- Middlesex County
- Coordinates
- 42.6459, -71.2984
- Drainage Area
- 4,635 mi²
- Datum (ft)
- 4.4
- HUC Code
- 01070006
Flood Stage Thresholds
- Action Stage
- 50.0 ft
- Flood Stage
- 52.0 ft
- Moderate Flood
- 54.0 ft
- Major Flood
- 58.0 ft
Currently 8.00 ft below flood stage.
Recent Extremes
- Max discharge
-
44,200 cfsMay 11, 2025
- Min discharge
-
681 cfsSep 23, 2025
- Days at flood stage
- 0
Computed from the local daily-values archive.
Nearby Gauges
-
Concord River Below River Meadow Brook, at Lowell, MANormal0.7 mi · 323 cfs
-
Shawsheen River Near Wilmington, MANormal6.9 mi · 18 cfs
-
Shawsheen River at Balmoral Street at Andover, MALow7.8 mi · 44 cfs
-
Nashoba Brook Near Acton, MANormal10.7 mi · 15 cfs
-
Nashua River at East Pepperell, MANormal14.1 mi · 282 cfs