The monitoring network within this area

Hydrionis holds 537 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

537

Values held

1917–2026

Record spans

Gauges within the Molokai 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 Halawa Stream near Halawa, Molokai, HI

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1918–2025.

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	Halawa Stream near Halawa, Molokai, HI (m³/s)
1918	32.0
1920	47.0
1921	39.9
1923	68.0
1924	22.8
1927	171
1929	25.4
1930	82.4
1938	140
1939	104
1940	69.1
1941	137
1943	223
1944	43.9
1946	123
1948	277
1949	94.3
1950	91.2
1952	109
1954	87.5
1955	175
1957	105
1959	74.5
1960	74.5
1961	309
1963	108
1964	42.5
1965	762
1966	87.8
1968	72.8
1969	81.3
1970	69.9
1972	50.1
1973	27.9
1974	50.4
1976	53.5
1978	141
1979	68.8
1981	50.4
1982	69.1
1983	45.9
1985	80.1
1986	74.2
1987	57.5
1989	67.1
1990	60.0
1991	66.8
1992	62.3
1994	55.2
1995	41.6
1996	38.8
1998	17.5
2000	88.3
2002	66.8
2004	74.8
2006	82.7
2007	68.2
2008	68.8
2009	69.4
2010	66.8
2011	65.4
2013	63.7
2014	89.2
2015	74.2
2016	53.5
2017	62.0
2018	76.2
2020	63.1
2021	75.6
2023	51.5
2024	78.4
2025	84.7

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	1918–2025
Completeness	66.7% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	29 separate periods inside 1918–2025 hold no value. The longest runs from 1931 to 1937 — 7 years with no reading. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1918 and is not continuous from it: 108 years separate the first value from the last, and 67% 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 Halawa Stream near Halawa, Molokai, HI, as a depth

The year's flow spread over the land draining to this gauge, in millimetres — the same unit rainfall is measured in. 1918–2025.

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	Halawa Stream near Halawa, Molokai, HI (mm)
1918	2,932
1921	2,674
1922	2,166
1923	2,483
1924	1,640
1925	1,864
1926	1,459
1927	2,711
1928	2,157
1929	2,026
1930	2,498
1931	1,967
1938	2,932
1939	2,822
1940	2,290
1941	2,741
1942	2,888
1943	2,490
1944	1,906
1945	1,503
1946	2,276
1947	2,306
1948	2,889
1949	1,658
1950	2,232
1951	1,893
1952	2,187
1953	1,481
1954	2,107
1955	2,424
1956	2,179
1957	2,129
1958	2,321
1959	1,864
1960	2,298
1961	3,293
1962	2,416
1963	3,094
1964	3,088
1965	2,608
1966	1,849
1967	1,938
1968	2,046
1969	2,291
1970	1,982
1971	1,319
1972	1,507
1973	1,753
1974	1,606
1975	1,201
1976	1,795
1977	1,540
1978	2,262
1979	2,269
1980	2,756
1981	1,923
1982	3,337
1983	1,739
1984	1,167
1985	1,871
1986	2,439
1987	2,932
1988	2,645
1989	2,969
1990	2,881
1991	2,026
1992	2,475
1993	1,974
1994	2,416
1995	1,650
1996	1,899
1997	2,453
1998	1,857
1999	1,599
2000	1,839
2001	1,790
2002	2,085
2003	1,820
2004	2,563
2005	2,070
2006	2,313
2007	1,739
2008	1,337
2009	1,753
2010	1,650
2011	1,473
2012	1,411
2013	1,901
2014	2,976
2015	2,748
2016	3,376
2017	1,989
2018	3,190
2019	1,761
2020	2,142
2021	2,380
2022	1,378
2023	1,886
2024	1,588
2025	1,326

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	1918–2025
Completeness	92.6% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	2 separate periods inside 1918–2025 hold no value. The longest runs from 1932 to 1937 — 6 years with no reading. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1918 and is not continuous from it: 108 years separate the first value from the last, and 93% 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 Molokai and what each holds
Gauge	Measures	Values	Record
Halawa Stream near Halawa, Molokai, HI	catchment area, annual maximum river flow, mean river flow, mean river flow, water year	301	1917–2026
Waikolu Str blw pipe nr Kalaupapa, Molokai, HI	catchment area, annual maximum river flow, mean river flow, mean river flow, water year	207	1920–2026
PELEKUNU STREAM NR PELEKUNU, MOLOKAI, HI	catchment area, annual maximum river flow	29	1920–2026

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 — 20050000. 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
Halawa Stream near Halawa, Molokai, HI	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
Waikolu Str blw pipe nr Kalaupapa, Molokai, HI	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
PELEKUNU STREAM NR PELEKUNU, MOLOKAI, HI	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 2 of them, which makes it a profile, not indexed.

Information-gain signals held for this water body
Signal	Held	Counts
Gauges holding a real record	2	no
Years spanned	110	yes, 20 or more
Values held	537	no
Distinct measurements	4	yes, 2 or more
Publishers measuring it	1	no
Official identifiers	1	recorded, not counted

Use this data

Machine-readable JSON /api/v1/observations/by-subject/gauge-usgs-16400000.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), Molokai gauge records, accessed 2026-10-05, hydrionis.com/waters/united-states-molokai/

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 Molokai 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 confidence2025-04-18

Source: USGS — National Water Information System, USGS site 16400000, 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.