Rivermatics

USGS Streamgage 11181040

San Lorenzo C A San Lorenzo, CA

San Lorenzo C A San Lorenzo, CA is USGS streamgage 11181040 in California, monitoring river discharge in hydrologic subbasin 18050004. It drains a watershed of about 45 square miles. Discharge records at this site go back to 1967. Typical flow runs near 1.8 cfs in July and 14.4 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.

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Gauge details

State
California
Drainage area
45 sq mi
Gauge elevation
8 ft
Subbasin (HUC-8)
18050004
Coordinates
37.6841, -122.13996
USGS site number
11181040
Records begin
1967-10-01 (59 years)
Rivermatics forecast
14-day flow outlook

14-day flow forecast

Based on observations through for San Lorenzo C A San Lorenzo, 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.

Forecast daily mean discharge in cubic feet per second, by date
Date Low p10 Expected p50 High p90 Range
12.2 15 18.4
10.2 14.4 19.3
8.3 13.5 18.5
7.1 13.2 18.5
4.2 12.3 17.4
3 11.5 16.8
2.3 10.8 16.3
2 10.6 16.8
1.7 9.8 16.3
1.4 9.2 16
1.4 9.2 17.6
1.2 7.6 15
1.1 6.9 14.7
1.1 6.1 14.2

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 59 years of data), averaged within each month. These describe the historical normal range — they are not a forecast and not today's reading.

Historical monthly discharge percentiles in cubic feet per second
Month Low p10 Typical p50 High p90 Range
January 1.8 14 176
February 2.6 23.8 168
March 3.1 23.4 128.2
April 2.6 14.4 59.1
May 1.5 5.7 22.4
June 0.8 3.1 10.1
July 0.6 1.8 4.7
August 0.5 1.4 3
September 0.5 1.2 3.2
October 0.6 1.5 8.9
November 0.8 2.5 24
December 1.2 6.1 83.3

All values in cubic feet per second (cfs).

Common questions

When does San Lorenzo C A San Lorenzo, CA normally run highest?
February, on the long-term record. The median daily flow that month is about 23.8 cfs, against 1.2 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 C A San Lorenzo, CA?
It depends on the month. In January, half of days historically fall near 14 cfs, with the middle 80% of days between 1.8 and 176 cfs. The month-by-month table on this page gives the full range.
How long has San Lorenzo C A San Lorenzo, CA been measured?
Discharge records at USGS site 11181040 begin in 1967, about 59 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 C A San Lorenzo, 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 C A San Lorenzo, CA?
The gauge sits at 37.6841, -122.13996, in California, in hydrologic subbasin 18050004, at an elevation of about 8 feet, draining roughly 45 square miles.
Can I use San Lorenzo C A San Lorenzo, 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.

Other gauges in this subbasin