USGS Streamgage 11051499
Santa Ana River near Mentone (River Only), CA
Santa Ana River near Mentone (River Only), CA is USGS streamgage 11051499 in California, monitoring river discharge in hydrologic subbasin 18070203. It sits on the Santa Ana River, alongside 3 other gauges Rivermatics tracks on the same river. It drains a watershed of about 210 square miles. Discharge records at this site go back to 1994. Typical flow runs near 0.2 cfs in July and 29.1 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
- 210 sq mi
- Gauge elevation
- 1,956 ft
- Subbasin (HUC-8)
- 18070203
- Coordinates
- 34.10834, -117.10059
- USGS site number
- 11051499
- Records begin
- 1994-10-01 (32 years)
- Rivermatics forecast
- 14-day flow outlook
14-day flow forecast
Based on observations through for Santa Ana River near Mentone (River Only), 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 |
|---|---|---|---|---|
| 27.5 | 29.4 | 30.7 | ||
| 22.5 | 28.9 | 31.5 | ||
| 13.4 | 28.2 | 33.4 | ||
| 12.7 | 27.9 | 34 | ||
| 12.9 | 27.9 | 34.8 | ||
| 15.5 | 28 | 35.5 | ||
| 15.2 | 27.8 | 36.1 | ||
| 12.8 | 27.5 | 36.5 | ||
| 11.1 | 27.1 | 36.9 | ||
| 9.3 | 26.8 | 37.5 | ||
| 8 | 26.4 | 37.9 | ||
| 6.8 | 26.1 | 38.4 | ||
| 7 | 25.3 | 39.9 | ||
| 4.6 | 24.2 | 38.4 |
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 32 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 | 0 | 0.2 | 109.8 | |
| February | 0 | 2.2 | 119.2 | |
| March | 0 | 4.9 | 303.2 | |
| April | 0.1 | 29.1 | 253.1 | |
| May | 0 | 3.7 | 189.7 | |
| June | 0 | 0.7 | 95.7 | |
| July | 0 | 0.2 | 55.3 | |
| August | 0 | 0 | 29.9 | |
| September | 0 | 0 | 20.9 | |
| October | 0 | 0.1 | 22.8 | |
| November | 0 | 0.1 | 13.8 | |
| December | 0 | 0.2 | 25.7 |
All values in cubic feet per second (cfs).
Common questions
- When does Santa Ana River near Mentone (River Only), CA normally run highest?
- April, on the long-term record. The median daily flow that month is about 29.1 cfs, against 0 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 Santa Ana River near Mentone (River Only), CA?
- It depends on the month. In January, half of days historically fall near 0.2 cfs, with the middle 80% of days between 0 and 109.8 cfs. The month-by-month table on this page gives the full range.
- How long has Santa Ana River near Mentone (River Only), CA been measured?
- Discharge records at USGS site 11051499 begin in 1994, about 32 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 Santa Ana River near Mentone (River Only), 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 Santa Ana River near Mentone (River Only), CA?
- The gauge sits at 34.10834, -117.10059, in California, in hydrologic subbasin 18070203, at an elevation of about 1,956 feet, draining roughly 210 square miles.
- Can I use Santa Ana River near Mentone (River Only), 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 Santa Ana River
Every gauge Rivermatics tracks on this river, ordered by drainage area — upstream first. See the Santa Ana River in full.
- Santa Ana River near Mentone (River Only), CA this page
- Santa Ana River near Mentone, CA 210 sq mi
- Santa Ana River below Prado Dam, CA 2,258 sq mi
- Santa Ana River near Mentone Cn + Cn, CA