The monitoring network within this area

Hydrionis holds 363 values from 2 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

363

Values held

1912–2026

Record spans

Gauges within the Mad-Redwood huc8 subbasin

2 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 REDWOOD C A ORICK CA

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1912–2024.

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	REDWOOD C A ORICK CA (m³/s)
1912	552
1948	850
1950	1,019
1951	793
1952	680
1953	1,416
1954	796
1955	1,416
1957	682
1959	496
1960	705
1961	617
1962	739
1964	1,068
1966	1,121
1968	422
1969	487
1970	793
1972	1,407
1974	702
1975	1,422
1976	343
1977	93.7
1979	399
1980	549
1981	750
1982	835
1983	507
1985	323
1986	869
1987	166
1988	606
1990	513
1991	150
1992	142
1993	334
1995	527
1997	1,141
1998	564
2000	564
2001	65.7
2002	671
2003	490
2004	433
2005	852
2006	314
2008	351
2010	250
2012	411
2014	254
2016	532
2017	430
2019	487
2020	221
2021	247
2022	223
2024	1,209

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	1912–2024
Completeness	50.4% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	22 separate periods inside 1912–2024 hold no value. The longest runs from 1913 to 1947 — 35 years with no reading. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1912 and is not continuous from it: 113 years separate the first value from the last, and 50% of the years between them are held. The span is not the record.
Last read from the publisher	2026-08-31
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 REDWOOD C A ORICK 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. 1912–2024.

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	REDWOOD C A ORICK CA (mm)
1912	1,694
1954	1,261
1955	1,400
1956	1,541
1957	1,535
1958	1,308
1959	858
1960	1,301
1961	1,363
1962	1,182
1963	1,407
1964	1,985
1965	878
1966	1,318
1967	1,061
1968	1,201
1969	1,227
1970	1,649
1971	1,622
1972	1,561
1973	1,792
1974	1,220
1975	1,865
1976	687
1977	779
1978	939
1979	1,146
1980	1,113
1981	1,460
1982	1,831
1983	2,285
1984	1,437
1985	594
1986	1,297
1987	860
1988	813
1989	1,003
1990	810
1991	551
1992	518
1993	1,414
1994	713
1995	1,689
1996	1,996
1997	1,101
1998	1,862
1999	1,260
2000	950
2001	661
2002	1,092
2003	1,286
2004	929
2005	1,466
2006	1,714
2007	1,027
2008	1,056
2009	786
2010	1,460
2011	1,013
2012	1,420
2013	369
2014	830
2015	760
2016	1,393
2017	1,704
2018	904
2019	1,150
2020	519
2021	768
2022	638
2023	1,147
2024	1,792

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	1912–2024
Completeness	63.7% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	One period inside 1912–2024 holds no value: 1913 to 1953, 41 years with no reading. It is drawn as a break in the line and is never interpolated across.
Continuity	The record begins in 1912 and is not continuous from it: 113 years separate the first value from the last, and 64% of the years between them are held. The span is not the record.
Last read from the publisher	2026-08-24
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 Mad-Redwood and what each holds
Gauge	Measures	Values	Record
REDWOOD C A ORICK CA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow	188	1912–2026
MAD R NR ARCATA CA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow	175	1912–2026

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 — 18010102. 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
REDWOOD C A ORICK 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	2026-08-26
MAD R NR ARCATA 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	2026-08-26

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 3 of them, which makes it a full profile.

Information-gain signals held for this water body
Signal	Held	Counts
Gauges holding a real record	2	no
Years spanned	115	yes, 20 or more
Values held	363	no
Distinct measurements	4	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-11482500.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), Mad-Redwood gauge records, accessed 2026-09-02, hydrionis.com/waters/united-states-mad-redwood/

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 Mad-Redwood 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 confidence2024-12-29

Source: USGS — National Water Information System, USGS site 11482500, 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 31 August 2026.