CNRFC - Hydrology - Observed River/Reservoir Conditions

SANTA MARGARITA RIVER - YSIDORA (YDRC1)

Latitude: 33.31º N	Longitude: 117.35º W	Elevation: 75 Feet
Location: San Diego County in California		Bulletin Group: Southern California		River Group: San Diego/Inland

Action/Monitor: 10.85 Feet

Minor Flood: 12.5 Feet

Moderate Flood: 13.78 Feet

Major Flood: 16.29 Feet

Plot Type:

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

Historical Mean Daily Stage/Flow Data
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
Upstream Photo	Gage House Photo	Downstream Photo

ESRI™ Locator Map

Flood Impacts
16.29 Feet	Major flood, 37,000 cfs. Widespread inundation of Camp Pendleton with evacuations likely. Flood of Record Jan 16, 1993.
13.78 Feet	Moderate 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 Feet	Minor flood stage, 8,000 cfs. Vandegrift Road has begun to flood downstream of the gage. Stuart Mesa Road closures can be expected.
10.85 Feet	2,500 cfs. The river has reached monitor stage. Personnel begin regular patrols along the levee.

Official 7 Day National Weather Service Forecast (CAZ043)

Tonight: Showers This Evening, then showers and a slight chance of thunderstorms overnight. Locally heavy rainfall possible This Evening. Lows 49 to 54. Areas of winds south 10 mph with gusts to 25 mph becoming northwest overnight.

Tuesday: Showers likely and a slight chance of thunderstorms. Highs around 61. Areas of winds southwest 10 mph. Chance of measurable precipitation 70 percent.

Tuesday Night: Partly cloudy with a chance of showers. Lows 45 to 49. Light winds. Chance of measurable precipitation 50 percent.

Wednesday: Partly cloudy in the morning and becoming mostly sunny. Highs 60 to 63. Light winds becoming west 10 mph in the afternoon.

Wednesday Night: Mostly clear in the evening and becoming partly cloudy. Lows 46 to 51. Light winds.

Thursday: Partly cloudy. A chance of showers in the afternoon. Highs 60 to 64.

Thursday Night: Showers likely. Lows 49 to 54.

Friday: Cloudy in the morning and becoming partly cloudy. A chance of showers. Highs 60 to 64.

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

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

Saturday Night: Partly cloudy with a slight chance of showers. Lows 48 to 52.

Sunday: Partly cloudy in the morning and becoming mostly sunny. Highs 64 to 68.

Sunday Night: Mostly clear in the evening and becoming partly cloudy. Lows 49 to 53.

Monday: Partly cloudy in the morning and becoming mostly sunny. Highs 64 to 69.

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.

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