USGS Streamgage 11172955
Alameda C below Diversion Dam near Sunol, CA
Alameda C below Diversion Dam near Sunol, CA is USGS streamgage 11172955 in California, monitoring river discharge in hydrologic subbasin 18050004. It drains a watershed of about 35 square miles. Discharge records at this site go back to 2010. Typical flow runs near 0.4 cfs in July and 12.2 cfs in April, with the higher of the two arriving in April.
Gauge details
- State
- California
- Drainage area
- 35 sq mi
- Gauge elevation
- 836 ft
- Subbasin (HUC-8)
- 18050004
- Coordinates
- 37.49861, -121.77944
- USGS site number
- 11172955
- Records begin
- 2010-10-01 (16 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 16 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 | 0.1 | 4.6 | 293.6 | |
| February | 0.4 | 4.1 | 293.2 | |
| March | 0.9 | 13.6 | 232 | |
| April | 1 | 12.2 | 45.1 | |
| May | 0.5 | 3.3 | 12.2 | |
| June | 0.2 | 1.5 | 4.4 | |
| July | 0 | 0.4 | 1.6 | |
| August | 0 | 0.1 | 0.6 | |
| September | 0 | 0 | 0.3 | |
| October | 0 | 0.1 | 2.5 | |
| November | 0 | 0.2 | 2.6 | |
| December | 0.1 | 2.4 | 152.9 |
All values in cubic feet per second (cfs).
Common questions
- When does Alameda C below Diversion Dam near Sunol, CA normally run highest?
- March, on the long-term record. The median daily flow that month is about 13.6 cfs, against 0 cfs in September, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
- What is a normal flow for Alameda C below Diversion Dam near Sunol, CA?
- It depends on the month. In January, half of days historically fall near 4.6 cfs, with the middle 80% of days between 0.1 and 293.6 cfs. The month-by-month table on this page gives the full range.
- How long has Alameda C below Diversion Dam near Sunol, CA been measured?
- Discharge records at USGS site 11172955 begin in 2010, about 16 years, covering roughly 5,784 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
- Where is Alameda C below Diversion Dam near Sunol, CA?
- The gauge sits at 37.49861, -121.77944, in California, in hydrologic subbasin 18050004, at an elevation of about 836 feet, draining roughly 35 square miles.
- Can I use Alameda C below Diversion Dam near Sunol, CA 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.