USGS Streamgage 11318500
SF Mokelumne River near West Point, CA
SF Mokelumne River near West Point, CA is USGS streamgage 11318500 in California, monitoring river discharge in hydrologic subbasin 18040012. It drains a watershed of about 75 square miles. Discharge records at this site go back to 1933. Typical flow runs near 17.2 cfs in July and 143.5 cfs in April, with the higher of the two arriving in April.
Gauge details
- State
- California
- Drainage area
- 75 sq mi
- Gauge elevation
- 1,950 ft
- Subbasin (HUC-8)
- 18040012
- Coordinates
- 38.36825, -120.54548
- USGS site number
- 11318500
- Records begin
- 1933-10-01 (93 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 92 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 | 11.5 | 44.6 | 332.3 | |
| February | 20.7 | 87 | 376.1 | |
| March | 38 | 128.7 | 418.5 | |
| April | 33.1 | 143.5 | 396.5 | |
| May | 15.5 | 79.9 | 294.6 | |
| June | 7.8 | 36.4 | 102.1 | |
| July | 2.7 | 17.2 | 44.9 | |
| August | 1.4 | 9.9 | 23.9 | |
| September | 1.2 | 7.9 | 19.1 | |
| October | 2.6 | 10.7 | 23.1 | |
| November | 4.7 | 15.5 | 46.2 | |
| December | 7.8 | 23.7 | 160 |
All values in cubic feet per second (cfs).
Common questions
- When does SF Mokelumne River near West Point, CA normally run highest?
- April, on the long-term record. The median daily flow that month is about 143.5 cfs, against 7.9 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 SF Mokelumne River near West Point, CA?
- It depends on the month. In January, half of days historically fall near 44.6 cfs, with the middle 80% of days between 11.5 and 332.3 cfs. The month-by-month table on this page gives the full range.
- How long has SF Mokelumne River near West Point, CA been measured?
- Discharge records at USGS site 11318500 begin in 1933, about 93 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 SF Mokelumne River near West Point, CA?
- The gauge sits at 38.36825, -120.54548, in California, in hydrologic subbasin 18040012, at an elevation of about 1,950 feet, draining roughly 75 square miles.
- Can I use SF Mokelumne River near West Point, 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.