The monitoring network within this area

Hydrionis holds 378 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

378

Values held

1921–2026

Record spans

Gauges within the Lower Colorado-Marble Canyon 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 COLORADO RIVER NEAR GRAND CANYON, AZ

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1921–2023.

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	COLORADO RIVER NEAR GRAND CANYON, AZ (m³/s)
1921	4,814
1922	3,256
1923	3,171
1924	2,095
1925	1,521
1926	2,424
1927	3,596
1928	3,256
1929	3,143
1930	2,010
1931	980
1932	2,888
1933	2,308
1934	722
1935	2,973
1936	2,161
1937	2,415
1938	2,832
1939	1,388
1940	1,325
1941	3,398
1942	2,599
1943	1,892
1944	2,645
1945	1,792
1946	1,419
1947	2,268
1948	2,543
1949	3,171
1950	1,654
1951	1,804
1952	3,455
1953	1,940
1954	929
1955	1,144
1956	1,903
1957	3,540
1958	3,058
1959	1,085
1960	1,311
1961	1,127
1962	2,424
1964	558
1965	1,654
1966	603
1967	677
1968	759
1969	872
1970	782
1971	946
1972	835
1973	1,085
1974	799
1975	818
1976	784
1977	909
1978	833
1980	1,274
1981	719
1982	790
1983	2,724
1984	1,348
1985	1,342
1986	1,515
1987	895
1988	722
1989	886
1990	799
1991	821
1992	564
1993	966
1994	623
1995	719
1996	1,356
1997	892
1999	733
2000	929
2001	549
2002	606
2003	595
2004	603
2006	572
2008	1,283
2009	501
2010	606
2011	756
2012	1,322
2013	1,079
2014	1,102
2016	578
2018	586
2020	578
2021	589
2022	586
2023	1,220

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	1921–2023
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 1921–2023 hold no value. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1921 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	2026-08-31
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 COLORADO RIVER NEAR GRAND CANYON, AZ, as a depth

The year's flow spread over the land draining to this gauge, in millimetres — the same unit rainfall is measured in. 1923–2025.

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	COLORADO RIVER NEAR GRAND CANYON, AZ (mm)
1923	62.0
1924	41.0
1925	44.0
1926	47.0
1927	63.0
1928	52.0
1929	69.0
1930	44.0
1931	23.0
1932	55.0
1933	35.0
1934	14.0
1935	37.0
1936	43.0
1937	43.0
1938	55.0
1939	31.0
1940	28.0
1941	65.0
1942	52.0
1943	40.0
1944	46.0
1945	42.0
1946	32.0
1947	50.0
1948	45.0
1949	51.0
1950	37.0
1951	34.0
1952	63.0
1953	30.0
1954	22.0
1955	25.0
1956	30.0
1957	65.0
1958	47.0
1959	25.0
1960	32.0
1961	27.0
1962	51.0
1963	6.00
1964	12.0
1965	41.0
1966	28.0
1967	28.0
1968	32.0
1969	33.0
1970	30.0
1971	33.0
1972	34.0
1973	34.0
1974	32.0
1975	32.0
1976	33.0
1977	26.0
1978	32.0
1979	30.0
1980	41.0
1981	27.0
1982	32.0
1983	68.0
1984	71.0
1985	59.0
1986	66.0
1987	41.0
1988	29.0
1989	29.0
1990	28.0
1991	31.0
1995	37.0
1996	39.0
1997	54.0
1998	44.0
1999	42.0
2000	31.0
2001	29.0
2002	28.0
2003	30.0
2004	31.0
2005	31.0
2006	31.0
2007	31.0
2008	34.0
2009	31.0
2010	31.0
2011	49.0
2012	30.0
2013	29.0
2014	29.0
2015	32.0
2016	34.0
2017	32.0
2018	33.0
2019	34.0
2020	30.0
2021	29.0
2022	26.0
2023	32.0
2024	28.0
2025	27.0

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	1923–2025
Completeness	97.1% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	One period inside 1923–2025 holds no value: 1992 to 1994, 3 years with no reading. It is drawn as a break in the line and is 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 97% 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 Lower Colorado-Marble Canyon and what each holds
Gauge	Measures	Values	Record
COLORADO RIVER NEAR GRAND CANYON, AZ	burned area within 50 km, catchment area, annual maximum river flow, mean river flow	240	1921–2026
BRIGHT ANGEL CREEK NEAR GRAND CANYON, ARIZ.	burned area within 50 km, catchment area, annual maximum river flow, mean river flow	138	1924–2026

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 — 15010001. 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
COLORADO RIVER NEAR GRAND CANYON, AZ	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
BRIGHT ANGEL CREEK NEAR GRAND CANYON, ARIZ.	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	106	yes, 20 or more
Values held	378	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-09402500.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), Lower Colorado-Marble Canyon gauge records, accessed 2026-09-02, hydrionis.com/waters/united-states-lower-colorado-marble-canyon/

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 Lower Colorado-Marble Canyon 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 confidence2023-04-25

Source: USGS — National Water Information System, USGS site 09402500, 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.