The monitoring network within this area

Hydrionis holds 778 values from 3 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

778

Values held

1881–2026

Record spans

Gauges within the Lower Iowa huc8 subbasin

3 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 Iowa River at Iowa City, IA

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1881–2025.

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	Iowa River at Iowa City, IA (m³/s)
1881	1,444
1903	637
1904	280
1905	276
1906	337
1907	368
1908	170
1909	354
1910	357
1911	487
1912	566
1913	199
1914	272
1915	566
1916	456
1917	496
1918	1,203
1919	391
1920	235
1921	442
1922	167
1923	243
1924	564
1925	45.0
1926	504
1927	309
1929	620
1930	385
1931	79.0
1933	246
1934	60.6
1935	247
1936	365
1937	484
1938	142
1939	279
1940	85.5
1941	212
1942	221
1943	300
1944	881
1945	271
1946	419
1947	957
1948	510
1949	399
1950	388
1951	445
1952	294
1953	337
1954	218
1955	130
1956	87.8
1957	133
1958	142
1959	266
1960	303
1961	281
1962	348
1963	233
1964	85.0
1965	314
1966	286
1967	125
1969	425
1970	242
1971	314
1972	300
1973	320
1974	337
1975	297
1976	208
1977	148
1978	269
1979	303
1980	160
1981	176
1982	294
1983	269
1984	267
1985	297
1986	286
1988	126
1989	91.7
1990	382
1991	388
1992	229
1993	799
1994	267
1995	270
1996	195
1997	297
1998	282
1999	220
2000	195
2001	314
2002	132
2003	179
2004	214
2005	179
2006	142
2007	286
2008	1,164
2009	311
2010	323
2011	241
2012	100
2013	564
2014	564
2015	253
2017	223
2018	311
2020	300
2021	225
2022	197
2023	184
2024	303
2025	314

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	1881–2025
Completeness	81.4% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	7 separate periods inside 1881–2025 hold no value. The longest runs from 1882 to 1902 — 21 years with no reading. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1881 and is not continuous from it: 145 years separate the first value from the last, and 81% 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 Iowa River at Iowa City, IA, as a depth

The year's flow spread over the land draining to this gauge, in millimetres — the same unit rainfall is measured in. 1959–2025.

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	Iowa River at Iowa City, IA (mm)
1959	198
1960	287
1961	232
1962	294
1963	110
1964	70.0
1965	358
1966	184
1967	94.0
1968	73.0
1969	361
1970	200
1971	181
1972	281
1973	437
1974	394
1975	214
1976	130
1977	101
1978	225
1979	326
1980	122
1981	104
1982	380
1983	439
1984	363
1985	144
1986	397
1987	174
1988	72.0
1989	32.0
1990	286
1991	386
1992	314
1993	889
1994	204
1995	238
1996	184
1997	209
1998	364
1999	254
2000	101
2001	284
2002	140
2003	149
2004	233
2005	172
2006	141
2007	434
2008	637
2009	497
2010	524
2011	250
2012	72.0
2013	323
2014	311
2015	369
2016	412
2017	260
2018	449
2019	497
2020	293
2021	130
2022	152
2023	109
2024	201
2025	277

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	1959–2025
Completeness	100.0% of the periods in that span are held.
Continuity	Continuous: every year from 1959 to 2025 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

Every gauge Hydrionis holds within this area

Gauges within the Lower Iowa and what each holds
Gauge	Measures	Values	Record
Iowa River at Iowa City, IA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	295	1881–2026
Iowa River at Wapello, IA	catchment area, annual maximum river flow, mean river flow, mean river flow, water year	258	1903–2026
Ralston Creek at Iowa City, IA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	225	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 — 07080209. 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
Iowa River at Iowa City, IA	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
Iowa River at Wapello, IA	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
Ralston Creek at Iowa City, IA	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 4 of them, which makes it a full profile.

Information-gain signals held for this water body
Signal	Held	Counts
Gauges holding a real record	3	yes, 3 or more
Years spanned	146	yes, 20 or more
Values held	778	no
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-05454500.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 Iowa gauge records, accessed 2026-10-05, hydrionis.com/waters/united-states-lower-iowa/

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 Iowa 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 confidence2025-08-10

Source: USGS — National Water Information System, USGS site 05454500, 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.