USGS Streamgage 11303500
San Joaquin River near Vernalis, CA
San Joaquin River near Vernalis, CA is USGS streamgage 11303500 in California, monitoring river discharge in hydrologic subbasin 18040003. It sits on the San Joaquin River, alongside 10 other gauges Rivermatics tracks on the same river. It drains a watershed of about 13,539 square miles. Discharge records at this site go back to 1923. Typical flow runs near 1,289.7 cfs in July and 2,959.7 cfs in April, with the higher of the two arriving in April. Rivermatics issues a daily machine-learned flow outlook for this gauge, reaching 14 days ahead.
View live conditions & forecast →
Gauge details
- State
- California
- Drainage area
- 13,539 sq mi
- Gauge elevation
- 3 ft
- Subbasin (HUC-8)
- 18040003
- Coordinates
- 37.67601, -121.26629
- USGS site number
- 11303500
- Records begin
- 1923-10-01 (103 years)
- Rivermatics forecast
- 14-day flow outlook
14-day flow forecast
Based on observations through for San Joaquin River near Vernalis, CA. Each day carries a median estimate and the band the model expects the flow to fall within — not a single number to plan against. Forecasts are re-issued daily; see the live screen for the current outlook.
| Date | Low p10 | Expected p50 | High p90 | Range |
|---|---|---|---|---|
| 524 | 584 | 651 | ||
| 503 | 598 | 737 | ||
| 493 | 608 | 809 | ||
| 492 | 620 | 884 | ||
| 484 | 623 | 914 | ||
| 472 | 624 | 934 | ||
| 467 | 626 | 963 | ||
| 459 | 626 | 985 | ||
| 452 | 625 | 995 | ||
| 444 | 621 | 982 | ||
| 439 | 626 | 1,003 | ||
| 450 | 654 | 1,093 | ||
| 449 | 665 | 1,137 | ||
| 447 | 665 | 1,145 |
All values in cubic feet per second (cfs). Estimates only — do not use them for navigation or for any safety, rescue, or emergency decision.
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 103 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 | 1,138.1 | 2,598.7 | 11,351.6 | |
| February | 1,213.7 | 3,274.8 | 16,034.5 | |
| March | 980.8 | 3,334.2 | 19,393.5 | |
| April | 810 | 2,959.7 | 21,553.3 | |
| May | 739 | 3,296.5 | 21,835.5 | |
| June | 541.4 | 2,482.3 | 17,606.7 | |
| July | 357.6 | 1,289.7 | 6,659.4 | |
| August | 360.6 | 1,088.7 | 3,117.1 | |
| September | 434.5 | 1,282.3 | 3,208.3 | |
| October | 800.1 | 1,821 | 3,795.2 | |
| November | 975.1 | 1,735.3 | 3,441 | |
| December | 976.5 | 2,055.5 | 5,455.2 |
All values in cubic feet per second (cfs).
Common questions
- When does San Joaquin River near Vernalis, CA normally run highest?
- March, on the long-term record. The median daily flow that month is about 3,334.2 cfs, against 1,088.7 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 Joaquin River near Vernalis, CA?
- It depends on the month. In January, half of days historically fall near 2,598.7 cfs, with the middle 80% of days between 1,138.1 and 11,351.6 cfs. The month-by-month table on this page gives the full range.
- How long has San Joaquin River near Vernalis, CA been measured?
- Discharge records at USGS site 11303500 begin in 1923, about 103 years, covering roughly 9,130 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
- Is there a flow forecast for San Joaquin River near Vernalis, CA?
- Yes. Rivermatics trains a machine-learned model — a temporal-fusion transformer — on this basin's observed flows, weather, and snowpack, and issues a daily flow outlook reaching 14 days ahead: a median estimate inside a confidence band, not a single number to bet on. Every forecast is scored against days the model never trained on, and that track record is published on the live gauge screen. Open live conditions to see the current outlook.
- Where is San Joaquin River near Vernalis, CA?
- The gauge sits at 37.67601, -121.26629, in California, in hydrologic subbasin 18040003, at an elevation of about 3 feet, draining roughly 13,539 square miles.
- Can I use San Joaquin River near Vernalis, 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.
Upstream and downstream on the San Joaquin River
Every gauge Rivermatics tracks on this river, ordered by drainage area — upstream first. See the San Joaquin River in full.
- San Joaquin River Ab Shakeflat C near Big Creek, CA 1,003 sq mi
- San Joaquin River Ab Willow C near Auberry, CA 1,295 sq mi
- San Joaquin River near Auberry, CA 1,461 sq mi
- San Joaquin River below Friant, CA 1,676 sq mi
- San Joaquin River below Hwy 41 near Pinedale, CA 1,785 sq mi
- San Joaquin River below Chowchilla Cn Intake near Mendota 1,822 sq mi
- San Joaquin River near Mendota, CA 3,940 sq mi
- San Joaquin River near Stevinson, CA 7,473 sq mi
- San Joaquin River Ab Merced River near Newman, CA 7,949 sq mi
- San Joaquin River near Newman, CA 9,520 sq mi
- San Joaquin River near Vernalis, CA this page