USGS Streamgage 11469000
Mattole River near Petrolia, CA
Mattole River near Petrolia, CA is USGS streamgage 11469000 in California, monitoring river discharge in hydrologic subbasin 18010107. It drains a watershed of about 245 square miles. Discharge records at this site go back to 1911. Typical flow runs near 68.9 cfs in July and 691.4 cfs in April, with the higher of the two arriving in April.
Gauge details
- State
- California
- Drainage area
- 245 sq mi
- Gauge elevation
- 50 ft
- Subbasin (HUC-8)
- 18010107
- Coordinates
- 40.31316, -124.28335
- USGS site number
- 11469000
- Records begin
- 1911-10-01 (115 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 115 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 | 329.2 | 1,671.3 | 8,481.9 | |
| February | 402.3 | 1,553.8 | 7,432.8 | |
| March | 418.2 | 1,379.3 | 5,177.4 | |
| April | 267 | 691.4 | 2,713 | |
| May | 166.2 | 316.1 | 990.2 | |
| June | 82.7 | 143.4 | 375.8 | |
| July | 40.8 | 68.9 | 139.9 | |
| August | 23.7 | 38.7 | 67.2 | |
| September | 18.6 | 30.5 | 71.3 | |
| October | 21.6 | 47.9 | 434 | |
| November | 47.6 | 315.1 | 3,099 | |
| December | 121 | 1,203.3 | 7,377.4 |
All values in cubic feet per second (cfs).
Common questions
- When does Mattole River near Petrolia, CA normally run highest?
- January, on the long-term record. The median daily flow that month is about 1,671.3 cfs, against 30.5 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 Mattole River near Petrolia, CA?
- It depends on the month. In January, half of days historically fall near 1,671.3 cfs, with the middle 80% of days between 329.2 and 8,481.9 cfs. The month-by-month table on this page gives the full range.
- How long has Mattole River near Petrolia, CA been measured?
- Discharge records at USGS site 11469000 begin in 1911, about 115 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 Mattole River near Petrolia, CA?
- The gauge sits at 40.31316, -124.28335, in California, in hydrologic subbasin 18010107, at an elevation of about 50 feet, draining roughly 245 square miles.
- Can I use Mattole River near Petrolia, 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.