USGS Streamgage 11180825
San Lorenzo C Ab Don Castro Reservoir near Castro V, CA
San Lorenzo C Ab Don Castro Reservoir near Castro V, CA is USGS streamgage 11180825 in California, monitoring river discharge in hydrologic subbasin 18050004. It drains a watershed of about 18 square miles. Discharge records at this site go back to 1980. Typical flow runs near 0.4 cfs in July and 3 cfs in April, with the higher of the two arriving in April.
Gauge details
- State
- California
- Drainage area
- 18 sq mi
- Gauge elevation
- 236 ft
- Subbasin (HUC-8)
- 18050004
- Coordinates
- 37.69517, -122.04492
- USGS site number
- 11180825
- Records begin
- 1980-10-01 (46 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 46 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 | 0.3 | 2.5 | 37.4 | |
| February | 0.6 | 4.5 | 69.5 | |
| March | 0.8 | 5.7 | 48.7 | |
| April | 0.7 | 3 | 19.3 | |
| May | 0.4 | 1.5 | 6.8 | |
| June | 0.1 | 0.8 | 3 | |
| July | 0 | 0.4 | 1.3 | |
| August | 0 | 0.2 | 0.7 | |
| September | 0 | 0.2 | 0.5 | |
| October | 0 | 0.3 | 1.4 | |
| November | 0.1 | 0.5 | 5.4 | |
| December | 0.3 | 1 | 21.9 |
All values in cubic feet per second (cfs).
Common questions
- When does San Lorenzo C Ab Don Castro Reservoir near Castro V, CA normally run highest?
- March, on the long-term record. The median daily flow that month is about 5.7 cfs, against 0.2 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 San Lorenzo C Ab Don Castro Reservoir near Castro V, CA?
- It depends on the month. In January, half of days historically fall near 2.5 cfs, with the middle 80% of days between 0.3 and 37.4 cfs. The month-by-month table on this page gives the full range.
- How long has San Lorenzo C Ab Don Castro Reservoir near Castro V, CA been measured?
- Discharge records at USGS site 11180825 begin in 1980, about 46 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 San Lorenzo C Ab Don Castro Reservoir near Castro V, CA?
- The gauge sits at 37.69517, -122.04492, in California, in hydrologic subbasin 18050004, at an elevation of about 236 feet, draining roughly 18 square miles.
- Can I use San Lorenzo C Ab Don Castro Reservoir near Castro V, 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.