USGS Streamgage 11160500
San Lorenzo River A Big Trees, CA
San Lorenzo River A Big Trees, CA is USGS streamgage 11160500 in California, monitoring river discharge in hydrologic subbasin 18060015. It drains a watershed of about 106 square miles. Discharge records at this site go back to 1936. Typical flow runs near 23.9 cfs in July and 89.6 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
- 106 sq mi
- Gauge elevation
- 230 ft
- Subbasin (HUC-8)
- 18060015
- Coordinates
- 37.04439, -122.07246
- USGS site number
- 11160500
- Records begin
- 1936-10-01 (90 years)
- Rivermatics forecast
- 14-day flow outlook
14-day flow forecast
Based on observations through for San Lorenzo River A Big Trees, 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 |
|---|---|---|---|---|
| 17.4 | 17.9 | 18.4 | ||
| 17.1 | 17.8 | 18.5 | ||
| 16.9 | 17.8 | 18.6 | ||
| 16.6 | 17.6 | 18.6 | ||
| 16.4 | 17.5 | 18.5 | ||
| 16.3 | 17.5 | 18.6 | ||
| 16.1 | 17.4 | 18.6 | ||
| 15.7 | 17.1 | 18.5 | ||
| 15.5 | 17 | 18.4 | ||
| 15.8 | 17.3 | 18.9 | ||
| 16.4 | 18.3 | 21.4 | ||
| 16.2 | 18.2 | 20.7 | ||
| 15.9 | 17.8 | 20 | ||
| 15.6 | 17.5 | 19.5 |
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 90 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 | 22 | 80.7 | 809.7 | |
| February | 29.6 | 144 | 970.9 | |
| March | 34.7 | 145.4 | 666.2 | |
| April | 28.3 | 89.6 | 360.6 | |
| May | 20.5 | 53.4 | 142.1 | |
| June | 14.5 | 34.2 | 75 | |
| July | 10.6 | 23.9 | 45.9 | |
| August | 9.7 | 18.3 | 33.3 | |
| September | 9.1 | 16.4 | 27.1 | |
| October | 10.3 | 17.6 | 30.9 | |
| November | 13.1 | 24.2 | 81.7 | |
| December | 18.1 | 39.6 | 366.3 |
All values in cubic feet per second (cfs).
Common questions
- When does San Lorenzo River A Big Trees, CA normally run highest?
- March, on the long-term record. The median daily flow that month is about 145.4 cfs, against 16.4 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 San Lorenzo River A Big Trees, CA?
- It depends on the month. In January, half of days historically fall near 80.7 cfs, with the middle 80% of days between 22 and 809.7 cfs. The month-by-month table on this page gives the full range.
- How long has San Lorenzo River A Big Trees, CA been measured?
- Discharge records at USGS site 11160500 begin in 1936, about 90 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 Lorenzo River A Big Trees, 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 Lorenzo River A Big Trees, CA?
- The gauge sits at 37.04439, -122.07246, in California, in hydrologic subbasin 18060015, at an elevation of about 230 feet, draining roughly 106 square miles.
- Can I use San Lorenzo River A Big Trees, 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.