CNRFC - Hydrology - River Guidance - Graphical RVF

Location:

SAN JOAQUIN RIVER - PATTERSON (PATC1)

Latitude: 37.49º N	Longitude: 121.08º W	Elevation: 97 Feet
Location: Stanislaus County in California		Bulletin Group: San Joaquin		River Group: San Joaquin

Issuance Time:

Dec 25 2025 at 2:10 PM PST

Next Issuance:

Dec 26 2025 at 9:00 AM PST

Action/Monitor: 48.0 Feet

Minor Flood: 54.7 Feet

Moderate Flood: 57.3 Feet

Major Flood: 58.3 Feet

Plot Type:

Please Note:
1) Each individual timeseries plotted on the graphical river forecast can be toggled on and off by clicking the legend entry above. If the "Observed (Raw Data)" contains bad data and is toggled off, the plot will scale to the remaining timeseries.

2) At extremely low river flows, the "Observed (Raw Data)" may show readings below the lower end of the available rating table, while the "Observed (Simulated)" will only show values at the bottom of the rating table, creating a potential discrepancy between the two readings.

Observed Data Credit
	Raw streamflow data is provided by the California Department of Water Resources. View California Department of Water Resources 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*	3,474	37.43	Mar 23, 2025
2024*	5,740	41.64	Mar 7, 2024
2023*	24,500	52.24	Mar 27, 2023
2022*	1,190	33.41	Dec 31, 2021
2021*	1,770	34.50	Feb 1, 2021
Historical High Stage/Flow Events (Period of Record - Oct 1969 to Present) - Ranked by Flow
1983*	28,700	51.26	Mar 4, 1983
2006*	27,612	50.97	Apr 10, 2006
2017*	25,600	51.71	Feb 22, 2017
1980*	24,900	50.57	Feb 25, 1980
2023*	24,500	52.24	Mar 27, 2023
1986*	23,000	49.65	Mar 18, 1986

* Discharge affected by regulation or diversion
** Most recent continuous record back to Oct 1969 with segmented periods back to Apr 1938

Location Photographs
Upstream Photo	Gage House Photo	Downstream Photo

ESRI™ Locator Map

Flood Impacts
58.3 Feet	Stages above 58.3 feet result in flooding outside the levee. Top of levee.

Official 7 Day National Weather Service Forecast (CAZ019)

Today: Mostly cloudy. A chance of rain in the morning, then a chance of rain showers early in the afternoon. A slight chance of thunderstorms in the afternoon. Rain showers late in the afternoon. Some thunderstorms may produce heavy rainfall in the afternoon. Highs 50 to 58. Southeast winds 10 to 20 mph with gusts to around 35 mph.

Tonight: Mostly cloudy. A chance of rain in the evening, then a slight chance of rain after midnight. Lows 40 to 46. Southeast winds 10 to 15 mph with gusts to around 25 mph.

Saturday: Partly cloudy. Highs 47 to 52. Southwest winds up to 10 mph shifting to the northwest in the afternoon.

Saturday Night: Mostly clear. Lows 35 to 40. Northwest winds up to 10 mph.

Sunday: Mostly cloudy in the morning then clearing. Highs around 47. Northwest winds up to 10 mph with gusts to around 20 mph.

Sunday Night: Mostly clear. Lows around 37.

Monday: Mostly cloudy. Highs 45 to 51.

Monday Night: Partly cloudy. Lows around 37.

Tuesday: Mostly cloudy. Highs 47 to 53.

Tuesday Night: Mostly clear. Lows around 38.

Wednesday and Wednesday Night: Mostly cloudy. Highs 47 to 53. Lows around 40.

New Years Day: Mostly cloudy with a slight chance of rain. Highs around 51.

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.

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