USGS Streamgage 11435100
Pyramid C A Twin Bridges, CA
Pyramid C A Twin Bridges, CA is USGS streamgage 11435100 in California, monitoring river discharge in hydrologic subbasin 18020129. It drains a watershed of about 9 square miles. Discharge records at this site go back to 1970. Typical flow runs near 53.5 cfs in July and 38.1 cfs in April, with the higher of the two arriving in July.
Gauge details
- State
- California
- Drainage area
- 9 sq mi
- Subbasin (HUC-8)
- 18020129
- Coordinates
- 38.81574, -120.11713
- USGS site number
- 11435100
- Records begin
- 1970-10-01 (56 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 55 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 | 5.9 | 13.8 | 33.1 | |
| February | 8.5 | 14.8 | 35.5 | |
| March | 11.8 | 20.4 | 45.3 | |
| April | 20 | 38.1 | 77.5 | |
| May | 34.5 | 91.9 | 172.5 | |
| June | 19.6 | 86.7 | 220.3 | |
| July | 21.4 | 53.5 | 124.1 | |
| August | 5.2 | 38.9 | 79.3 | |
| September | 1.1 | 7.5 | 53.2 | |
| October | 0.6 | 5.1 | 27.7 | |
| November | 2.6 | 10 | 37.5 | |
| December | 4.9 | 12.4 | 33.6 |
All values in cubic feet per second (cfs).
Common questions
- When does Pyramid C A Twin Bridges, CA normally run highest?
- May, on the long-term record. The median daily flow that month is about 91.9 cfs, against 5.1 cfs in October, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
- What is a normal flow for Pyramid C A Twin Bridges, CA?
- It depends on the month. In January, half of days historically fall near 13.8 cfs, with the middle 80% of days between 5.9 and 33.1 cfs. The month-by-month table on this page gives the full range.
- How long has Pyramid C A Twin Bridges, CA been measured?
- Discharge records at USGS site 11435100 begin in 1970, about 56 years, covering roughly 8,821 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
- Where is Pyramid C A Twin Bridges, CA?
- The gauge sits at 38.81574, -120.11713, in California, in hydrologic subbasin 18020129, draining roughly 9 square miles.
- Can I use Pyramid C A Twin Bridges, 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.