11 USGS Streamgages
San Joaquin River flows and levels
San Joaquin River is gauged at 11 USGS streamgages in California, each tracked by Rivermatics. It feeds the New York Slough. Drainage area at the gauges ranges from 1,003 square miles at San Joaquin River Ab Shakeflat C near Big Creek, CA up to 13,539 at San Joaquin River near Vernalis, CA. The gauged reach falls about 2,863 feet, from 2,866 feet down to 2. Rivermatics issues a daily machine-learned 14-day flow outlook at 4 of them.
Gauges on this river, upstream to downstream
Ordered by drainage area, which is how far down the river each gauge sits. April and July figures are long-term median daily flows for that month from the USGS record — historical normals, not a forecast and not today's reading.
| Gauge | State | Drainage sq mi | Elevation ft | April p50 cfs | July p50 cfs | Forecast |
|---|---|---|---|---|---|---|
| San Joaquin River Ab Shakeflat C near Big Creek, CA | CA | 1,003 | 2,866 | 23.4 | 35.5 | — |
| San Joaquin River Ab Willow C near Auberry, CA | CA | 1,295 | 1,176 | 31.2 | 29.1 | — |
| San Joaquin River near Auberry, CA | CA | 1,461 | — | 32.8 | 36.9 | — |
| San Joaquin River below Friant, CA | CA | 1,676 | 297 | 325.3 | 239.2 | 14-day + temp |
| San Joaquin River below Hwy 41 near Pinedale, CA | CA | 1,785 | 260 | 371 | 352.4 | — |
| San Joaquin River below Chowchilla Cn Intake near Mendota | CA | 1,822 | 170 | 132.1 | 120.3 | — |
| San Joaquin River near Mendota, CA | CA | 3,940 | 133 | 4,272 | 1,556.8 | — |
| San Joaquin River near Stevinson, CA | CA | 7,473 | 71 | 167.3 | 32.1 | — |
| San Joaquin River Ab Merced River near Newman, CA | CA | 7,949 | 3 | 418.1 | 145.8 | 14-day + temp |
| San Joaquin River near Newman, CA | CA | 9,520 | 2 | 841.2 | 374.5 | 14-day |
| San Joaquin River near Vernalis, CA | CA | 13,539 | 3 | 2,959.7 | 1,289.7 | 14-day |
Typical flow by month at San Joaquin River near Vernalis, CA
The furthest-downstream gauge on this river, so the fullest flow it carries here. 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 the San Joaquin River run highest?
- March, on the long-term record at San Joaquin River near Vernalis, CA — the furthest-downstream gauge Rivermatics tracks on this river. Median daily flow there is about 3,334.2 cfs that month, against 1,088.7 cfs in August, the lowest. Upstream gauges peak on their own schedule; the table on this page gives April and July for each.
- How many gauges are on the San Joaquin River?
- Rivermatics tracks 11 USGS streamgages on the San Joaquin River, across California. Each has its own page with the site's full flow record and monthly normals. The river may carry other gauges that publish neither daily values nor discharge statistics; those are not tracked here.
- Is there a flow forecast for the San Joaquin River?
- Yes, at 4 of the 11 gauges. Rivermatics trains a machine-learned model — a temporal-fusion transformer — on each basin's observed flows, weather and snowpack, and issues a daily 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 each gauge's live screen.
- Can I use San Joaquin River 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.