USGS Streamgage 11047300
Arroyo Trabuco A San Juan Capistrano, CA
Arroyo Trabuco A San Juan Capistrano, CA is USGS streamgage 11047300 in California, monitoring river discharge in hydrologic subbasin 18070301. It drains a watershed of about 54 square miles. Discharge records at this site go back to 1972. Typical flow runs near 1.3 cfs in July and 4.8 cfs in April, with the higher of the two arriving in April.
Gauge details
- State
- California
- Drainage area
- 54 sq mi
- Gauge elevation
- 65 ft
- Subbasin (HUC-8)
- 18070301
- Coordinates
- 33.49836, -117.66587
- USGS site number
- 11047300
- Records begin
- 1972-10-01 (54 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 54 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 | 1.5 | 5.4 | 69.5 | |
| February | 1.7 | 7.2 | 156.3 | |
| March | 1.9 | 8.7 | 78.7 | |
| April | 1.3 | 4.8 | 36.5 | |
| May | 0.7 | 3 | 15.9 | |
| June | 0.3 | 1.7 | 8 | |
| July | 0.2 | 1.3 | 3.9 | |
| August | 0 | 0.9 | 3.5 | |
| September | 0.1 | 1 | 3.9 | |
| October | 0.1 | 1.5 | 7.1 | |
| November | 0.4 | 2.7 | 22.2 | |
| December | 1 | 4.7 | 63.7 |
All values in cubic feet per second (cfs).
Common questions
- When does Arroyo Trabuco A San Juan Capistrano, CA normally run highest?
- March, on the long-term record. The median daily flow that month is about 8.7 cfs, against 0.9 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 Arroyo Trabuco A San Juan Capistrano, CA?
- It depends on the month. In January, half of days historically fall near 5.4 cfs, with the middle 80% of days between 1.5 and 69.5 cfs. The month-by-month table on this page gives the full range.
- How long has Arroyo Trabuco A San Juan Capistrano, CA been measured?
- Discharge records at USGS site 11047300 begin in 1972, about 54 years, covering roughly 9,126 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
- Where is Arroyo Trabuco A San Juan Capistrano, CA?
- The gauge sits at 33.49836, -117.66587, in California, in hydrologic subbasin 18070301, at an elevation of about 65 feet, draining roughly 54 square miles.
- Can I use Arroyo Trabuco A San Juan Capistrano, 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.