USGS Streamgage 12161000
SF Stillaguamish River near Granite Falls, WA
SF Stillaguamish River near Granite Falls, WA is USGS streamgage 12161000 in Washington, monitoring river discharge in hydrologic subbasin 17110008. It drains a watershed of about 119 square miles. Discharge records at this site go back to 1928. Typical flow runs near 471.3 cfs in July and 994.3 cfs in April, with the higher of the two arriving in April.
Gauge details
- State
- Washington
- Drainage area
- 119 sq mi
- Gauge elevation
- 339 ft
- Subbasin (HUC-8)
- 17110008
- Coordinates
- 48.10369, -121.94567
- USGS site number
- 12161000
- Records begin
- 1928-08-01 (98 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 53 years of data), averaged within each month. These describe the historical normal range — they are not a forecast and not today's reading.
| Month | Low p10 | Typical p50 | High p90 | Range |
|---|---|---|---|---|
| January | 275.9 | 778.7 | 3,441.3 | |
| February | 303 | 755.7 | 2,628.3 | |
| March | 390.7 | 779.1 | 2,162.9 | |
| April | 585 | 994.3 | 2,012.7 | |
| May | 695.8 | 1,212.6 | 2,220.6 | |
| June | 498.1 | 1,001.5 | 1,975 | |
| July | 210.6 | 471.3 | 1,150.4 | |
| August | 104 | 205.2 | 612.9 | |
| September | 101.8 | 230.6 | 1,216.3 | |
| October | 161 | 541 | 2,481.3 | |
| November | 307.9 | 910.3 | 3,152.7 | |
| December | 407.1 | 1,070.3 | 3,771.3 |
All values in cubic feet per second (cfs).
Common questions
- When does SF Stillaguamish River near Granite Falls, WA normally run highest?
- May, on the long-term record. The median daily flow that month is about 1,212.6 cfs, against 205.2 cfs in August, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
- What is a normal flow for SF Stillaguamish River near Granite Falls, WA?
- It depends on the month. In January, half of days historically fall near 778.7 cfs, with the middle 80% of days between 275.9 and 3,441.3 cfs. The month-by-month table on this page gives the full range.
- How long has SF Stillaguamish River near Granite Falls, WA been measured?
- Discharge records at USGS site 12161000 begin in 1928, about 98 years, covering roughly 86 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
- Where is SF Stillaguamish River near Granite Falls, WA?
- The gauge sits at 48.10369, -121.94567, in Washington, in hydrologic subbasin 17110008, at an elevation of about 339 feet, draining roughly 119 square miles.
- Can I use SF Stillaguamish River near Granite Falls, WA data for flood or safety decisions?
- No. Rivermatics provides estimates, not guarantees, and the readings and forecasts here may be delayed, inaccurate, or wrong. Do not use them for navigation or for any safety, rescue, or emergency decision. Check the National Weather Service and USGS directly, and use your own judgment.