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

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SANTA MARGARITA RIVER - YSIDORA (YDRC1)
Latitude: 33.31º NLongitude: 117.35º WElevation: 75 Feet
Location: San Diego County in CaliforniaBulletin Group: Southern CaliforniaRiver Group: San Diego/Inland
Issuance Time: Dec 27 2025 at 9:19 AM PSTNext Issuance: Dec 28 2025 at 9:00 AM PST
Action/Monitor: 10.85 FeetMinor Flood: 12.5 FeetModerate Flood: 13.78 FeetMajor Flood: 16.29 Feet

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 US Geological Survey (USGS).
View US Geological Survey (USGS) 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
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*
708
9.10
Feb 14, 2025
2024*
8,250
11.26
Mar 31, 2024
2023*
11,100
11.73
Jan 16, 2023
2022*
4,270
9.37
Dec 24, 2021
2021*
1,120
7.31
Dec 29, 2020
 Historical High Stage/Flow Events (Period of Record - Sep 2001 to Present)** - Ranked by Flow
1993*
44,000***
20.47***
Jan 16, 1993
1927
33,600****
18.00
Feb 16, 1927
2017*
31,200
14.60
Jan 22, 2017
1938
31,000
12.70
Mar 3, 1938
2011* 30,000*** 12.29 Dec 22, 2010
2019*
29,500
15.07
Feb 14, 2019
* Discharge affected by regulation or diversion
** Most recent continuous record back to Sep 2001 with segmented periods back to Feb 1923
*** Estimated value
**** Highest flow since regulation by Skinner Reservoir began in 1974
Location Photographs
ESRI™ Locator Map
Flood Impacts
16.29 FeetMajor flood, 37,000 cfs. Widespread inundation of Camp Pendleton with evacuations likely. Flood of Record Jan 16, 1993.
13.78 FeetModerate flood stage, 17,000 cfs. Vandegrift Road is flooded for several miles downstream of the gage site. Stuart Mesa Road is flooded near the bridge.
12.5 FeetMinor flood stage, 8,000 cfs. Vandegrift Road has begun to flood downstream of the gage. Stuart Mesa Road closures can be expected.
10.85 Feet2,500 cfs. The river has reached monitor stage. Personnel begin regular patrols along the levee.
Official 7 Day National Weather Service Forecast   (CAZ043)
Tonight: Mostly clear. Lows 41 to 45. Light winds.

Sunday: Mostly sunny. Highs 65 to 69. Areas of winds northeast to 10 mph becoming northwest with gusts to 25 mph in the afternoon.

Sunday Night: Mostly clear. Lows 43 to 46. Areas of winds northeast 10 to 15 mph. Gusts to 25 mph in the evening.

Monday: Mostly sunny. Highs 67 to 71. Areas of winds east 10 to 20 mph. Gusts to 25 mph and becoming 30 mph in the afternoon.

Monday Night: Mostly clear in the evening and becoming partly cloudy. Lows 47 to 51. Areas of winds east 10 to 20 mph with gusts to 30 mph.

Tuesday: Partly cloudy. Highs 69 to 73.

Tuesday Night: Partly cloudy in the evening and becoming mostly cloudy. Lows 48 to 54.

Wednesday: Mostly cloudy with a slight chance of showers in the morning, then partly cloudy with a chance of showers in the afternoon. Highs 66 to 71.

Wednesday Night: Partly cloudy with a chance of showers in the evening, then mostly cloudy with showers likely overnight. Lows 51 to 56.

New Years Day: Showers likely. Highs 65 to 69.

Thursday Night: Showers likely. Lows 50 to 55.

Friday: Showers likely. Highs 64 to 67.

Friday Night: Partly cloudy with a chance of showers. Lows 50 to 54.

Saturday: Partly cloudy with a chance of showers. Highs 63 to 67.
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 San Diego 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.