National Weather Service California Nevada River Forecast Center Department of Commerce National Oceanic and Atmospheric Administration National Weather Service

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SAN JOAQUIN RIVER - VERNALIS (VNSC1)
Latitude: 37.68º NLongitude: 121.27º WElevation: 35 Feet
Location: San Joaquin County in CaliforniaRiver Group: San Joaquin
Monitor Stage: 24.5 FeetFlood Stage: 29.0 FeetDanger Stage: 29.5 Feet

Observed Data Credit
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Raw streamflow data is provided by the US Geological Survey (USGS).
View USGS Data for this station location.

Historical Stage/Flow Data
Note: Water Year 2025 is currently showing peak daily mean values. These will be updated to instantaneous peaks in the coming months.
Water Year
Peak Discharge (cfs)
Stage (feet)
Date
 Most Recent 5 Years
2025* 4,9400 12.97 Mar 20, 2025
2024* 10,300 18.12 Mar 6, 2024
2023* 34,400 29.82 Mar 19, 2023
2022* 2,600 10.83 Dec 29, 2021
2021* 2,470 10.76 Jan 31, 2021
 Historical High Stage/Flow Events (Period of Record - Jul 1922 to Present) - Ranked by Flow
1951* 79,000 27.75 Dec 09, 1950
1997* 75,600 34.88 Jan 05, 1997
1969* 52,600 34.55 Jan 27, 1969
1938* 51,200 26.64 Mar 16, 1938
1956* 50,900 26.89 Dec 25, 1955
1983* 45,100 31.49 Mar 07, 1983
 * Discharge affected by regulation or diversion
Location Photographs
ESRI™ Locator Map
Official 7 Day National Weather Service Forecast   (CAZ019)
Today: Mostly cloudy in the morning then becoming partly cloudy. Areas of fog and patchy frost in the morning. Highs around 56. Light winds.

Tonight: Partly cloudy. Patchy fog after midnight. Lows 36 to 42. Light winds.

Monday: Partly cloudy in the morning then clearing. Highs around 55. Light winds.

Monday Night: Mostly clear. Patchy fog after midnight. Lows around 40. Light winds.

Tuesday: Partly cloudy in the morning then clearing. Patchy fog in the morning. Highs 54 to 59. Light winds.

Tuesday Night: Mostly clear. Lows around 41.

Wednesday: Mostly sunny. Patchy fog. Highs 55 to 61.

Wednesday Night: Mostly clear. Patchy fog. Lows around 43.

Thursday: Partly cloudy. Patchy fog. Highs 57 to 63.

Thursday Night: Mostly clear. Patchy fog. Lows around 44.

Friday: Partly cloudy. Patchy fog. Highs 57 to 62.

Friday Night: Mostly clear. Lows around 44.

Saturday: Partly cloudy. Highs around 59.
Flood Impacts
37.29 FeetStages above 37.3 feet results in flooding outside the levees. Top of levee.
29.6 FeetHomes along east bank of river on Airport Court in Manteca experience flooding.
26.0 FeetSevere seepage occurs outside the levees. The area covered by seepage will increase as the river stage rises.
24.5 FeetMonitor Stage - water reaches the toe of levee.
21.0 FeetSeepage begins into crop area outside of levees.
Product Disclaimer

This river graphic is not intended to serve as a substitute for official flood watches, warnings, advisories, or statements issued by the NWS Sacramento Weather Forecast Office. Observations are preliminary and subject to change. River levels identified as "forecast" should be consistent with those contained in official NWS products. River levels identified as "guidance" have significant uncertainty due to future weather or reservoir regulation and are provided for planning purposes only.