USGS Streamgage 11141280
Lopez C near Arroyo Grande, CA
Lopez C near Arroyo Grande, CA is USGS streamgage 11141280 in California, monitoring river discharge in hydrologic subbasin 18060006. It drains a watershed of about 21 square miles. Discharge records at this site go back to 1967. Typical flow runs near 2.3 cfs in July and 6.3 cfs in April, with the higher of the two arriving in April.
Gauge details
- State
- California
- Drainage area
- 21 sq mi
- Gauge elevation
- 563 ft
- Subbasin (HUC-8)
- 18060006
- Coordinates
- 35.23552, -120.47235
- USGS site number
- 11141280
- Records begin
- 1967-07-21 (59 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 59 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 | 2.3 | 5.3 | 39.8 | |
| February | 2.4 | 6.7 | 69.2 | |
| March | 2.5 | 9.6 | 64.3 | |
| April | 2.1 | 6.3 | 29.7 | |
| May | 1.6 | 4.2 | 12 | |
| June | 1.4 | 3.1 | 8 | |
| July | 0.8 | 2.3 | 6.3 | |
| August | 0.7 | 2.1 | 4.9 | |
| September | 0.8 | 1.9 | 4.6 | |
| October | 1 | 2.3 | 4.6 | |
| November | 1.4 | 2.9 | 6 | |
| December | 1.8 | 3.8 | 12.6 |
All values in cubic feet per second (cfs).
Common questions
- When does Lopez C near Arroyo Grande, CA normally run highest?
- March, on the long-term record. The median daily flow that month is about 9.6 cfs, against 1.9 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 Lopez C near Arroyo Grande, CA?
- It depends on the month. In January, half of days historically fall near 5.3 cfs, with the middle 80% of days between 2.3 and 39.8 cfs. The month-by-month table on this page gives the full range.
- How long has Lopez C near Arroyo Grande, CA been measured?
- Discharge records at USGS site 11141280 begin in 1967, about 59 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 Lopez C near Arroyo Grande, CA?
- The gauge sits at 35.23552, -120.47235, in California, in hydrologic subbasin 18060006, at an elevation of about 563 feet, draining roughly 21 square miles.
- Can I use Lopez C near Arroyo Grande, 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.