The monitoring network within this area

Hydrionis holds 2,508 values from 8 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.

8

Gauges

2,508

Values held

1911–2026

Record spans

Gauges within the South Fork American huc8 subbasin

8 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 SILVER LK OUTLET NR KIRKWOOD CA

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1923–2025.

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	SILVER LK OUTLET NR KIRKWOOD CA (m³/s)
1923	7.73
1924	4.42
1925	7.39
1926	5.49
1927	12.1
1928	7.39
1929	12.7
1930	7.50
1931	3.51
1932	15.6
1933	7.50
1934	5.49
1935	8.24
1936	8.44
1937	15.4
1939	3.43
1940	11.9
1941	13.8
1942	12.7
1943	11.2
1944	15.4
1945	12.7
1946	8.21
1947	8.01
1948	8.18
1949	7.79
1950	10.6
1952	13.0
1953	12.0
1954	6.46
1955	13.8
1957	14.2
1958	15.5
1959	3.85
1960	7.05
1961	5.01
1962	7.59
1963	18.1
1964	4.59
1966	6.48
1967	14.1
1968	4.30
1969	18.4
1970	13.6
1971	8.41
1972	5.32
1973	12.6
1974	17.7
1975	22.5
1976	1.70
1977	2.41
1978	8.44
1979	9.43
1980	17.0
1981	4.93
1983	14.1
1984	14.5
1985	5.92
1986	32.8
1987	6.88
1988	1.33
1989	9.09
1990	3.54
1991	4.98
1992	2.83
1993	10.1
1994	2.78
1995	14.5
1996	25.3
1997	61.4
1998	11.7
1999	12.5
2000	12.5
2001	4.45
2002	7.45
2003	11.3
2004	7.31
2005	14.4
2007	3.71
2008	6.09
2009	7.82
2010	11.7
2011	23.2
2012	7.08
2014	5.75
2015	3.43
2016	6.88
2017	19.3
2018	12.2
2019	16.3
2020	11.9
2021	20.3
2023	14.4
2024	8.72
2025	4.67

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	1923–2025
Completeness	92.2% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	8 separate periods inside 1923–2025 hold no value. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1923 and is not continuous from it: 103 years separate the first value from the last, and 92% 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 SILVER LK OUTLET NR KIRKWOOD 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. 1923–2024.

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	SILVER LK OUTLET NR KIRKWOOD CA (mm)
1923	739
1924	341
1925	950
1926	506
1927	1,191
1928	737
1929	438
1930	597
1931	221
1932	944
1933	492
1934	281
1935	785
1936	983
1937	880
1938	1,220
1939	311
1940	935
1941	1,009
1942	1,084
1943	964
1944	573
1945	989
1946	848
1947	451
1948	691
1949	635
1950	1,263
1951	599
1952	1,231
1953	726
1954	646
1955	646
1956	1,244
1957	821
1958	1,096
1959	354
1960	398
1961	347
1962	828
1963	1,025
1964	587
1965	1,127
1966	508
1967	1,227
1968	482
1969	1,456
1970	971
1971	887
1972	612
1973	978
1974	1,055
1975	901
1976	198
1977	156
1978	1,021
1979	742
1980	1,185
1981	612
1982	1,538
1983	2,001
1984	1,046
1985	560
1986	1,420
1987	306
1988	243
1989	835
1990	381
1991	417
1992	298
1993	1,223
1994	297
1995	1,767
1996	1,167
1997	1,211
1998	1,363
1999	921
2000	714
2001	370
2002	676
2003	835
2004	530
2005	1,175
2006	1,440
2007	365
2008	466
2009	778
2010	964
2011	1,440
2012	462
2013	474
2014	225
2015	213
2016	1,112
2017	1,924
2018	633
2019	1,211
2020	382
2021	367
2022	470
2023	1,647
2024	698

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	Derived Computed by Hydrionis
Period held	1923–2024
Completeness	100.0% of the periods in that span are held.
Continuity	Continuous: every year from 1923 to 2024 is held.
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

The snow standing above this water

1 automated snow station sits inside this drainage area, weighing the snowpack rather than measuring how deep it is.

1,623

Fullest snowpack recorded at Carson Pass, in 2023 (mm of water)

283

Thinnest, in 2015 (mm of water)

March

Month the pack is usually at its fullest

June

Month the pack has gone by, in half of years

Peak snowpack at Carson Pass

Water years 2005–2026. Each point is the fullest month of that snow season.

A water year runs October to September and is named for the year it ends, so the snow of one winter stays in one point. The value is the fullest month, not the fullest day: a pack that peaked sharply mid-month reads lower here than a single measurement taken at the right moment would.

View the data behind this chart

Underlying data
Period	Carson Pass (mm)
2005	1,259
2006	1,445
2007	502
2008	679
2009	792
2010	881
2011	1,353
2012	455
2013	645
2014	445
2015	283
2016	766
2017	1,515
2018	538
2019	1,242
2020	597
2021	477
2022	445
2023	1,623
2024	742
2025	628
2026	429

Read against the river

Carson Pass and SILVER LK OUTLET NR KIRKWOOD CA both sit in this drainage area, and their records overlap by 20 years. That is the span the two have in common, not a count of years both actually hold — either record may have gaps inside it. The two are shown separately rather than on one axis: millimetres of stored water and cubic metres per second are not commensurable, and a difference between them would mean nothing.

Being in the same drainage area does not put the snowpack upstream of the gauge. A subbasin is an area, and snow on one tributary can join the river below a gauge on another — so a weak relationship here may say more about which tributary was measured than about the snow.

Every gauge Hydrionis holds within this area

Gauges within the South Fork American and what each holds
Gauge	Measures	Values	Record
SILVER LK OUTLET NR KIRKWOOD CA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	345	1922–2026
SF AMERICAN R NR KYBURZ(RIVER ONLY) CA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	345	1922–2026
SF AMERICAN R NR CAMINO CA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	344	1922–2026
SF SILVER C NR ICE HOUSE CA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	337	1924–2026
SF AMERICAN R NR KYBURZ TOTAL FLOW CA	burned area within 50 km, catchment area, mean river flow, mean river flow, water year	242	1922–2026
SF AMERICAN R NR PLACERVILLE CA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	240	1911–2026
ALDER C NR WHITE HALL (TOTAL FLOW) CA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	212	1922–2026
CAPLES LK OUTLET NR KIRKWOOD CA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	179	1923–2026

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 — 18020129. 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
SILVER LK OUTLET NR KIRKWOOD 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
SF AMERICAN R NR KYBURZ(RIVER ONLY) 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
SF AMERICAN R NR CAMINO 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
SF SILVER C NR ICE HOUSE 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
SF AMERICAN R NR KYBURZ TOTAL FLOW 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
SF AMERICAN R NR PLACERVILLE 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
ALDER C NR WHITE HALL (TOTAL FLOW) 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
CAPLES LK OUTLET NR KIRKWOOD 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	8	yes, 3 or more
Years spanned	116	yes, 20 or more
Values held	2,508	yes, 1000 or more
Distinct measurements	6	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-11436000.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), South Fork American gauge records, accessed 2026-10-05, hydrionis.com/waters/united-states-south-fork-american/

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 South Fork American 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 confidence2025-05-11

Source: USGS — National Water Information System, USGS site 11436000, 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.