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		River Group: Southern California

Monitor Stage: 10.85 Feet

Flood Stage: 12.5 Feet

Observed Data Credit
	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*	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

Official 7 Day National Weather Service Forecast (CAZ043)

Tonight: Mostly cloudy with a chance of showers. Lows around 57. Areas of winds south 10 mph. Chance of measurable precipitation 50 percent.

Sunday: Mostly cloudy in the morning and becoming partly cloudy. A chance of showers. A slight chance of thunderstorms in the afternoon. Highs around 65. Areas of winds south 10 to 15 mph. Chance of measurable precipitation 50 percent.

Sunday Night: Showers likely and a slight chance of thunderstorms. Lows 53 to 56. Areas of winds south 10 mph. Chance of measurable precipitation 70 percent.

Monday: Cloudy in the morning and becoming mostly cloudy. A chance of showers. Highs around 63. Areas of winds south to 10 mph. Chance of measurable precipitation 40 percent.

Monday Night: Cloudy. A slight chance of showers overnight. Lows 48 to 53. Areas of winds south 10 mph. Chance of measurable precipitation 20 percent.

Tuesday: Cloudy in the morning and becoming mostly cloudy. A chance of showers. Highs around 63.

Tuesday Night: Partly cloudy. A chance of showers. Lows 46 to 51.

Wednesday: Partly cloudy. A slight chance of showers in the morning. Highs around 63.

Wednesday Night: Partly cloudy. A slight chance of showers overnight. Lows 45 to 49.

Thursday: Partly cloudy in the morning and becoming mostly sunny. Highs 61 to 64.

Thursday Night: Partly cloudy. Lows 42 to 46.

Friday: Partly cloudy in the morning and becoming mostly sunny. Highs 63 to 66.

Friday Night: Mostly clear in the evening and becoming partly cloudy. Lows 44 to 47.

Saturday: Mostly sunny. Highs 66 to 69.

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.

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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