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

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COSUMNES RIVER - MCCONNELL (MCNC1)
Latitude: 38.36º NLongitude: 121.34º WElevation: 5 Feet
Location: Sacramento County in CaliforniaBulletin Group: San JoaquinRiver Group: North San Joaquin
Issuance Time: Jul 05 2025 at 7:41 AM PDTNext Issuance: Jul 06 2025 at 9:00 AM PDT
Action/Monitor: 38.5 FeetMinor Flood: 44.5 FeetModerate Flood: 53.4 FeetMajor Flood: 53.5 Feet
Please Note:On June 20, 2023, the datum was changed from USED to NAVD88 (+2.46 feet). As a result the monitor stage was updated to 38.5 ft and flood stage was updated to 44.5 ft.
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
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Raw streamflow data is provided by the California Department of Water Resources.
View California Department of Water Resources Data for this station location.

Verification - Historical Graphical RVF
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To view other verification locations, use our Historical Graphical River Forecast Interface.
Historical Stage/Flow Data
Water Year
Peak Discharge (cfs)
Stage (feet)
Date
 Most Recent 5 Years
2024*
13,400
42.98
Mar 2, 2024
2023*
73,600***
46.64***
Jan 1, 2023
2022*
7,790
38.99
Dec 24, 2021
2021*
3,000
32.00
Jan 29, 2021
2020*
6,890
38.18
Apr 6, 2020
 Historical High Stage/Flow Events (Period of Record - Jan 1952 to Present) - Ranked by Flow
1997*
--
48.50
Jan 02, 1997
1986
--
47.10
Feb 18, 1986
2023*
73,600***
46.64***
Jan 1, 2023
2006*
36,209
47.02
Jan 01, 2006
1998*
--
46.56
Feb 04, 1998
 * Discharge affected by regulation or diversion
 ** Dataum changed from USED to NAVD88 on 06/20/2023. The difference is +2.46 ft and must be applied to all data before date to convert to NAVD88.
 *** Estimated from simulated data. Gauge data not reliable from Jan 1, 2023 through Jan 10, 2023.
Location Photographs
ESRI™ Locator Map
Flood Impacts
46.5 FeetAt approximately 44,000 cfs, water exits the river upstream and downstream of Highway 99. Dillard Road is flooded from Highway 99 to Riley Road. Twin Cities Road is flooded from Hardesty Lane to Christensen Road.
44.5 FeetFlood stage.
41.5 FeetThe Cosumnes River overflow channel begins to flow.
38.5 FeetMonitor Stage.
Official 7 Day National Weather Service Forecast   (CAZ017)
Today: Sunny. Highs 84 to 90. South winds up to 10 mph.

Tonight: Clear. Lows 50 to 60. South winds up to 10 mph with gusts to around 20 mph.

Sunday: Sunny. Highs 88 to 96. Southwest winds up to 10 mph.

Sunday Night: Clear. Lows 53 to 62. Southwest winds up to 10 mph with gusts to around 20 mph.

Monday: Sunny. Highs 86 to 96. South winds up to 10 mph with gusts to around 20 mph.

Monday Night: Clear. Lows 53 to 61.

Tuesday: Sunny. Highs 84 to 92.

Tuesday Night and Wednesday: Clear. Lows 53 to 61. Highs 86 to 96.

Wednesday Night through Friday: Clear. Lows 60 to 70. Highs 93 to 103.
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.