The monitoring network within this area

Hydrionis holds 1,442 values from 6 gauges within it. Discharge is a property of a gauge and its reach, not of this drainage area, so this page reports the network and its records rather than a single figure.

Gauges

1,442

Values held

1906–2026

Record spans

Gauges within the San Diego huc8 subbasin

6 monitoring points, positioned as the publisher records them.

Flood peaks, as measured

This gauge's flood record, as measured. Unlike a daily mean it is the discharge at the moment the river was highest, which is the figure flood frequency analysis is built on.

Largest measured flow of each year at SAN DIEGO R A MAST RD NR SANTEE CA

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1915–2025.

Show relevant events (1 event)Shading marks when something was recorded, not what caused the line.

Published by the gauge's own operator from its sub-daily record; Hydrionis stores the figure rather than recomputing it. A year the gauge did not cover produces no value rather than a low one, and the gaps are stated below the chart. A peak is a property of this gauge and its reach: a larger flood upstream or downstream of it is not in this series.

What the shaded periods are (1 event)

A shaded period marks when something was recorded, not what caused the shape of the line. Where the two coincide, they coincided.

Documented record — A documented event, compiled from cited sources after it happened. The dates are as good as the record, which for older events can mean the month rather than the day.

Event	Type	Period	Standing	Authority
Hurricane Katrina water and sanitation collapse	Flood	2005-08-29 – 2005-09-30	Documented record	Compiled record

Not shown on this chart

The 1976 drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
The 2022 drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Yorkshire drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Cantareira water crisis, São Paulo — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Cape Town Day Zero — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
European drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.

View the data behind this chart

Underlying data
Period	SAN DIEGO R A MAST RD NR SANTEE CA (m³/s)
1915	112
1916	1,988
1917	29.4
1918	340
1919	2.80
1920	44.7
1921	0.425
1922	10.2
1926	129
1927	1,286
1928	4.42
1929	12.5
1930	21.5
1931	68.0
1932	210
1933	34.8
1934	0.198
1935	30.9
1936	35.1
1937	402
1938	208
1939	21.7
1940	33.1
1941	262
1942	3.31
1943	39.6
1944	24.3
1945	25.1
1947	5.38
1949	15.6
1950	0.510
1951	0.051
1952	124
1953	0.210
1954	18.6
1955	2.55
1956	1.76
1957	4.67
1958	77.9
1959	3.96
1960	5.55
1961	3.96
1962	46.4
1963	9.85
1964	13.5
1965	13.0
1966	96.3
1967	17.7
1969	51.8
1970	17.7
1971	6.51
1973	14.4
1974	18.6
1976	34.3
1977	24.4
1978	85.2
1979	76.2
1980	96.8
1981	38.8
1982	82.1
1983	272
1984	35.4
1985	63.7
1986	18.5
1987	19.2
1988	21.0
1990	22.5
1991	103
1992	71.9
1993	98.0
1994	28.3
1995	170
1996	30.3
1997	47.3
1998	154
1999	16.6
2000	44.5
2001	23.2
2002	14.9
2003	38.2
2004	48.7
2005	88.3
2006	27.4
2007	40.5
2008	26.2
2010	63.4
2011	30.0
2012	31.4
2014	11.5
2016	60.3
2017	112
2018	28.6
2019	75.3
2020	97.7
2021	25.5
2023	89.8
2024	116
2025	39.9

About this series

Everything below is a property of the data rather than a rating of it. There is deliberately no single confidence score: how much a gap matters depends on what you are about to do with the series, and only you know that.

Source	United States Geological Survey — National Water Information System · US Government work — public domain
How the values came to exist	Measured
Period held	1915–2025
Completeness	88.3% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	11 separate periods inside 1915–2025 hold no value. The longest runs from 1923 to 1925 — 3 years with no reading. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1915 and is not continuous from it: 111 years separate the first value from the last, and 88% of the years between them are held. The span is not the record.
Last read from the publisher	2026-10-01
Redistribution	Permitted by the upstream licences
Commercial reuse	Permitted by the upstream licences. No Hydrionis access tier can widen this.
Methodology	How this was produced

How much of the rain came back out

A discharge in cubic metres per second cannot be compared with anything: the larger number may only mean the larger catchment. Divided by the area draining to the gauge it becomes a depth of water over that land, which answers a question a reader already has — of the rain that fell here, how much came back out as river?

Water leaving the catchment above SAN DIEGO R A MAST RD NR SANTEE CA, as a depth

The year's flow spread over the land draining to this gauge, in millimetres — the same unit rainfall is measured in. 1913–2025.

Show relevant events (1 event)Shading marks when something was recorded, not what caused the line.

Computed by Hydrionis from the published annual mean flow and the catchment area the station's own publisher states. It is not a water balance: the difference between rainfall and runoff is not evaporation alone but also change in groundwater storage, water abstracted and taken elsewhere, and water imported by transfer schemes — which is why a catchment can yield more runoff than the rain that fell on it without anything being measured wrongly. A different area figure rescales every value here by the ratio between them.

What the shaded periods are (1 event)

A shaded period marks when something was recorded, not what caused the shape of the line. Where the two coincide, they coincided.

Documented record — A documented event, compiled from cited sources after it happened. The dates are as good as the record, which for older events can mean the month rather than the day.

Event	Type	Period	Standing	Authority
Hurricane Katrina water and sanitation collapse	Flood	2005-08-29 – 2005-09-30	Documented record	Compiled record

Not shown on this chart

The 1976 drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
The 2022 drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Yorkshire drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Cantareira water crisis, São Paulo — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Cape Town Day Zero — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
European drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.

View the data behind this chart

Underlying data
Period	SAN DIEGO R A MAST RD NR SANTEE CA (mm)
1913	2.00
1914	19.0
1915	107
1917	34.0
1918	27.0
1919	2.00
1920	25.0
1921	58.0
1922	148
1926	34.0
1927	192
1928	2.00
1929	2.00
1930	7.00
1931	7.00
1932	85.0
1933	22.0
1934	0
1935	5.00
1936	6.00
1937	44.0
1938	47.0
1939	16.0
1940	11.0
1941	182
1942	4.00
1943	7.00
1944	8.00
1945	3.00
1946	1.00
1947	1.00
1948	0
1949	2.00
1950	0
1951	2.00
1952	16.0
1953	0
1954	5.00
1955	0
1956	0
1957	1.00
1958	11.0
1959	2.00
1960	4.00
1961	3.00
1962	7.00
1963	4.00
1964	1.00
1965	14.0
1966	10.0
1967	5.00
1968	1.00
1969	19.0
1970	5.00
1971	5.00
1972	6.00
1973	12.0
1974	11.0
1975	15.0
1976	9.00
1977	6.00
1978	61.0
1979	29.0
1980	187
1981	13.0
1982	25.0
1983	79.0
1984	23.0
1985	15.0
1986	19.0
1987	13.0
1988	11.0
1989	4.00
1990	7.00
1991	24.0
1992	20.0
1993	72.0
1994	12.0
1995	46.0
1996	11.0
1997	11.0
1998	63.0
1999	8.00
2000	8.00
2001	11.0
2002	6.00
2003	13.0
2004	21.0
2005	35.0
2006	10.0
2007	8.00
2008	16.0
2009	13.0
2010	39.0
2011	18.0
2012	9.00
2013	7.00
2014	5.00
2015	6.00
2016	13.0
2017	23.0
2018	7.00
2019	21.0
2020	17.0
2021	8.00
2022	6.00
2023	35.0
2024	26.0
2025	9.00

About this series

Source	United States Geological Survey — National Water Information System · US Government work — public domain
How the values came to exist	Derived Computed by Hydrionis
Period held	1913–2025
Completeness	96.5% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	2 separate periods inside 1913–2025 hold no value. The longest runs from 1923 to 1925 — 3 years with no reading. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1913 and is not continuous from it: 113 years separate the first value from the last, and 96% of the years between them are held. The span is not the record.
Inputs last read	2026-10-01 · when the records this was computed from were last read from their publishers
Calculation date	2026-08-24 · when the calculation method was last versioned, not a reading of any publisher
Redistribution	Permitted by the upstream licences
Commercial reuse	Permitted by the upstream licences. No Hydrionis access tier can widen this.
Methodology	How this was produced

Every gauge Hydrionis holds within this area

Gauges within the San Diego and what each holds
Gauge	Measures	Values	Record
SAN DIEGO R A MAST RD NR SANTEE CA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	363	1912–2026
SANTA MARIA C NR RAMONA CA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	288	1913–2026
SANTA YSABEL C NR RAMONA CA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	266	1913–2026
SWEETWATER R NR DESCANSO CA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	265	1906–2026
SAN DIEGO R NR SANTEE CA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	231	1912–2026
SANTA YSABEL C NR SAN PASQUAL CA	catchment area, annual maximum river flow	29	1906–2026

How these gauges were attached to this water

Assigned by the publisher to a numbered basin Every gauge here is assigned to this drainage area by its own publisher, which issues the area an official code — 18070304. A drainage area is not a river: it contains the tributaries as well as the main channel, and a gauge in it may be on any of them.

What each gauge’s link to this water rests on
Gauge	Evidence	Established
SAN DIEGO R A MAST RD NR SANTEE CA	Stated by the publisher — USGS site service, huc_cd field — https://waterservices.usgs.gov/nwis/site/ ; named from the USGS Watershed Boundary Dataset 8-digit HU (Subbasin) layer — https://hydro.nationalmap.gov/arcgis/rest/services/wbd/MapServer/4	2026-10-02
SANTA MARIA C NR RAMONA CA	Stated by the publisher — USGS site service, huc_cd field — https://waterservices.usgs.gov/nwis/site/ ; named from the USGS Watershed Boundary Dataset 8-digit HU (Subbasin) layer — https://hydro.nationalmap.gov/arcgis/rest/services/wbd/MapServer/4	2026-10-02
SANTA YSABEL C NR RAMONA CA	Stated by the publisher — USGS site service, huc_cd field — https://waterservices.usgs.gov/nwis/site/ ; named from the USGS Watershed Boundary Dataset 8-digit HU (Subbasin) layer — https://hydro.nationalmap.gov/arcgis/rest/services/wbd/MapServer/4	2026-10-02
SWEETWATER R NR DESCANSO CA	Stated by the publisher — USGS site service, huc_cd field — https://waterservices.usgs.gov/nwis/site/ ; named from the USGS Watershed Boundary Dataset 8-digit HU (Subbasin) layer — https://hydro.nationalmap.gov/arcgis/rest/services/wbd/MapServer/4	2026-10-02
SAN DIEGO R NR SANTEE CA	Stated by the publisher — USGS site service, huc_cd field — https://waterservices.usgs.gov/nwis/site/ ; named from the USGS Watershed Boundary Dataset 8-digit HU (Subbasin) layer — https://hydro.nationalmap.gov/arcgis/rest/services/wbd/MapServer/4	2026-10-02
SANTA YSABEL C NR SAN PASQUAL CA	Stated by the publisher — USGS site service, huc_cd field — https://waterservices.usgs.gov/nwis/site/ ; named from the USGS Watershed Boundary Dataset 8-digit HU (Subbasin) layer — https://hydro.nationalmap.gov/arcgis/rest/services/wbd/MapServer/4	2026-10-02

What this record holds

Hydrionis decides which waters get a page, and which of those are offered to search, from what is actually held rather than from how the page reads. Five signals are counted; this record has 5 of them, which makes it a full profile.

Information-gain signals held for this water body
Signal	Held	Counts
Gauges holding a real record	5	yes, 3 or more
Years spanned	121	yes, 20 or more
Values held	1,442	yes, 1000 or more
Distinct measurements	5	yes, 2 or more
Publishers measuring it	2	yes, 2 or more
Official identifiers	1	recorded, not counted

Use this data

Machine-readable JSON /api/v1/observations/by-subject/gauge-usgs-11022480.json
How to cite this, and who you must credit
How these figures were produced
Request this at a different scale, format or geography

No bulk download is offered here, which is a licence position rather than a product one: at least one contributing publisher does not permit redistribution. The values can be read on the page, cited, and pointed to at source.

Attribution and citation

Suggested citation for Hydrionis

Hydrionis (2026), San Diego gauge records, accessed 2026-10-05, hydrionis.com/waters/united-states-san-diego/

Cite Hydrionis where you rely on values Hydrionis computed, on the method that produced them, or on the compilation itself. The underlying measurements remain the publishers’ and their attribution requirements apply to you directly.

Recommended, not required. Hydrionis does not claim rights over unmodified public data it relayed, and doing arithmetic on somebody else’s measurements does not make them Hydrionis’s. Cite the version and the access date: the San Diego gauge records changes as publishers release and as methods are revised, and a citation without both cannot be checked later. Full guidance is on cite and reuse.

None of the contributing licences requires attribution. Crediting the publishers is still good practice and they are listed above.

Where these figures come from

MeasuredHigh confidence2025-02-14

Source: USGS — National Water Information System, USGS site 11022480, annual peak streamflow. Licence: Open.

Method: The instantaneous maximum discharge of each water year as published by USGS, dated to the day it occurred. One value per October-to-September water year; where the publisher lists both a systematic and a historic peak for a year, the larger is the annual maximum. Values the publisher marks as maximum daily averages are not held here, because they are not instantaneous peaks. Values marked as bounded rather than measured are held as censored observations carrying the bound. Cubic feet per second are converted to cubic metres per second and the publisher unit is recorded alongside.

Rating curves are extrapolated at extreme discharges, so the largest values in a peak series carry the largest measurement uncertainty. Data from the U.S. Geological Survey National Water Information System, a work of the United States government and therefore in the public domain.

Retrieved 1 October 2026.