Largest rivers in Connecticut by average flow
Active USGS stream gauges in Connecticut, ranked by average flow. The Connecticut River at Thompsonville, CT gauge leads with 15,378 cfs.
| Rank | Name | Average flow |
|---|---|---|
| 1 | Connecticut River at Thompsonville, CT | 15,378 cfs |
| 2 | Housatonic River at Stevenson, CT | 2,400 cfs |
| 3 | Housatonic River at Gaylordsville, CT | 1,503 cfs |
| 4 | Quinebaug River at Jewett City, CT | 1,163 cfs |
| 5 | Farmington River at Tariffville, CT | 1,019 cfs |
| 6 | Housatonic River at Falls Village, CT | 963 cfs |
| 7 | Shetucket River at Taftville, CT | 832 cfs |
| 8 | Farmington River at Unionville, CT | 607 cfs |
| 9 | Shetucket River near Willimantic, CT | 603 cfs |
| 10 | Quinebaug River at Putnam, CT | 506 cfs |
| 11 | Naugatuck River at Beacon Falls, CT | 410 cfs |
| 12 | Quinebaug River at West Thompson, CT | 277 cfs |
| 13 | Natchaug River at Willimantic, CT | 249 cfs |
| 14 | Quinebaug River at Quinebaug, CT | 243 cfs |
| 15 | Naugatuck River at Waterbury, CT | 241 cfs |
| 16 | West Branch Farmington River at Riverton, CT | 236 cfs |
| 17 | French River at North Grosvenordale, CT | 181 cfs |
| 18 | Willimantic River near Coventry, CT | 178 cfs |
| 19 | Quinnipiac River at Wallingford, CT | 176 cfs |
| 20 | Willimantic River at Merrow Road. near Merrow, CT | 145 cfs |
| 21 | Salmon River near East Hampton, CT | 144 cfs |
| 22 | Naugatuck River at Thomaston, CT | 142 cfs |
| 23 | Still River at Robertsville, CT | 129 cfs |
| 24 | Yantic River at Yantic, CT | 124 cfs |
| 25 | Natchaug River at Marcy Road. near Chaplin, CT | 106 cfs |
| 25 | Hockanum River near East Hartford, CT | 106 cfs |
| 27 | Pomperaug River at Southbury, CT | 98.8 cfs |
| 28 | Still River at Route 7 at Brookfield Center, CT | 94.3 cfs |
| 29 | Saugatuck River near Westport, CT | 91.8 cfs |
| 30 | Shepaug River at Peters Dam at Woodville, CT | 51.6 cfs |
How the Average flow figures spread in Connecticut
- The ranking covers the 68 gauges in Connecticut that have a recorded average flow in this dataset.
- The highest is Connecticut River at Thompsonville, CT at 15,378 cfs; the lowest is Fivemile River near New Canaan, CT at 1.5 cfs.
- The median average flow is 41.8 cfs.
- The gap between #1 Connecticut River at Thompsonville, CT and #2 Housatonic River at Stevenson, CT is 12,978 cfs.
- The page table lists the top 30.
Data: U.S. Geological Survey (USGS) (public domain, U.S. federal data).· Updated 2026-11-02 · Text generated from the data and checked against it.
Live values are provisional USGS data. Measurements only, not a safety assessment — for flood warnings see the National Weather Service.