USGS Streamgage 11458000
Napa River near Napa, CA
Napa River near Napa, CA is USGS streamgage 11458000 in California, monitoring river discharge in hydrologic subbasin 18050002. It drains a watershed of about 218 square miles. Discharge records at this site go back to 1929. Typical flow runs near 3.6 cfs in July and 89.4 cfs in April, with the higher of the two arriving in April.
Gauge details
- State
- California
- Drainage area
- 218 sq mi
- Gauge elevation
- 27 ft
- Subbasin (HUC-8)
- 18050002
- Coordinates
- 38.36821, -122.30327
- USGS site number
- 11458000
- Records begin
- 1929-12-15 (97 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 67 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 | 7.5 | 131.8 | 1,794.8 | |
| February | 17.2 | 213.9 | 1,756.2 | |
| March | 29.9 | 207.6 | 1,166.8 | |
| April | 21.3 | 89.4 | 398.6 | |
| May | 9.6 | 33.3 | 114.5 | |
| June | 2.5 | 11.3 | 42.6 | |
| July | 0 | 3.6 | 14.4 | |
| August | 0 | 1.5 | 5.4 | |
| September | 0 | 0.5 | 4.1 | |
| October | 0 | 0.9 | 8.7 | |
| November | 0 | 5 | 101.8 | |
| December | 2.3 | 35.9 | 851.8 |
All values in cubic feet per second (cfs).
Common questions
- When does Napa River near Napa, CA normally run highest?
- February, on the long-term record. The median daily flow that month is about 213.9 cfs, against 0.5 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 Napa River near Napa, CA?
- It depends on the month. In January, half of days historically fall near 131.8 cfs, with the middle 80% of days between 7.5 and 1,794.8 cfs. The month-by-month table on this page gives the full range.
- How long has Napa River near Napa, CA been measured?
- Discharge records at USGS site 11458000 begin in 1929, about 97 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 Napa River near Napa, CA?
- The gauge sits at 38.36821, -122.30327, in California, in hydrologic subbasin 18050002, at an elevation of about 27 feet, draining roughly 218 square miles.
- Can I use Napa River near Napa, 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.