USGS Streamgage 11162570
San Gregorio C A San Gregorio, CA
San Gregorio C A San Gregorio, CA is USGS streamgage 11162570 in California, monitoring river discharge in hydrologic subbasin 18050006. It drains a watershed of about 51 square miles. Discharge records at this site go back to 1955. Typical flow runs near 2.2 cfs in July and 19.7 cfs in April, with the higher of the two arriving in April.
Gauge details
- State
- California
- Drainage area
- 51 sq mi
- Gauge elevation
- 14 ft
- Subbasin (HUC-8)
- 18050006
- Coordinates
- 37.32573, -122.38659
- USGS site number
- 11162570
- Records begin
- 1955-12-22 (71 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 57 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 | 2.4 | 21.1 | 263.2 | |
| February | 4.7 | 29.9 | 287.3 | |
| March | 4.7 | 34.2 | 242.7 | |
| April | 4.2 | 19.7 | 82.7 | |
| May | 1.9 | 9.3 | 26.3 | |
| June | 0.5 | 4.6 | 14.1 | |
| July | 0.1 | 2.2 | 7.8 | |
| August | 0 | 1.2 | 4.9 | |
| September | 0 | 0.7 | 3.5 | |
| October | 0 | 1.4 | 6.9 | |
| November | 0.6 | 3 | 30.6 | |
| December | 1.7 | 10 | 153.6 |
All values in cubic feet per second (cfs).
Common questions
- When does San Gregorio C A San Gregorio, CA normally run highest?
- March, on the long-term record. The median daily flow that month is about 34.2 cfs, against 0.7 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 San Gregorio C A San Gregorio, CA?
- It depends on the month. In January, half of days historically fall near 21.1 cfs, with the middle 80% of days between 2.4 and 263.2 cfs. The month-by-month table on this page gives the full range.
- How long has San Gregorio C A San Gregorio, CA been measured?
- Discharge records at USGS site 11162570 begin in 1955, about 71 years, covering roughly 8,488 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
- Where is San Gregorio C A San Gregorio, CA?
- The gauge sits at 37.32573, -122.38659, in California, in hydrologic subbasin 18050006, at an elevation of about 14 feet, draining roughly 51 square miles.
- Can I use San Gregorio C A San Gregorio, 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.