The monitoring network within this area

Hydrionis holds 437 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

437

Values held

1926–2026

Record spans

Gauges within the Lower Chehalis 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 SATSOP RIVER NEAR SATSOP, WA

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1929–2023.

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	SATSOP RIVER NEAR SATSOP, WA (m³/s)
1929	320
1931	544
1932	875
1933	433
1935	1,320
1936	470
1937	430
1939	725
1941	714
1943	371
1945	892
1946	487
1947	680
1949	835
1951	1,121
1952	447
1953	756
1954	830
1955	869
1956	991
1957	402
1959	810
1961	830
1962	929
1964	405
1966	756
1968	1,220
1970	515
1972	878
1973	634
1974	595
1975	968
1977	428
1979	869
1981	923
1982	878
1983	929
1984	402
1986	858
1987	589
1989	498
1990	773
1991	671
1993	665
1994	1,433
1995	872
1997	1,801
1998	1,002
1999	1,543
2001	232
2003	527
2005	827
2006	753
2007	1,031
2009	1,288
2010	1,039
2011	487
2012	818
2014	606
2015	739
2016	521
2017	1,218
2018	753
2020	1,056
2021	1,158
2022	1,563
2023	1,019

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	1929–2023
Completeness	70.5% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	28 separate periods inside 1929–2023 hold no value. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1929 and is not continuous from it: 95 years separate the first value from the last, and 71% 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 WYNOOCHEE RIVER ABOVE SAVE CREEK NEAR ABERDEEN, WA, as a depth

The year's flow spread over the land draining to this gauge, in millimetres — the same unit rainfall is measured in. 1926–2025.

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	WYNOOCHEE RIVER ABOVE SAVE CREEK NEAR ABERDEEN, WA (mm)
1926	3,231
1927	3,733
1928	3,476
1929	2,040
1930	2,478
1931	4,231
1932	4,163
1933	4,937
1934	4,171
1935	3,937
1936	3,084
1937	4,292
1938	2,997
1939	3,567
1940	3,627
1941	3,472
1942	2,873
1943	3,084
1944	2,680
1945	4,069
1946	3,654
1947	3,790
1948	3,713
1949	3,862
1950	4,853
1951	3,652
1952	3,005
1953	5,021
1954	4,607
1955	4,200
1956	4,488
1957	3,359
1958	4,016
1959	4,514
1960	3,876
1961	4,788
1962	3,676
1963	3,666
1964	3,650
1965	3,357
1966	4,171
1967	4,305
1968	4,969
1969	3,910
1970	3,609
1971	4,621
1972	4,616
1973	3,576
1974	4,844
1975	4,807
1976	3,109
1977	3,875
1978	2,973
1979	3,810
1980	4,132
1981	4,235
1982	4,214
1983	4,890
1984	4,083
1985	2,483
1986	3,750
1987	3,198
1988	3,323
1989	3,369
1990	4,615
1991	3,672
1992	3,178
1993	2,869
1994	4,271
1995	5,142
1996	4,019
1997	5,835
1998	4,632
1999	5,626
2000	2,994
2001	3,593
2002	4,009
2003	4,492
2004	3,281
2005	3,259
2006	4,479
2007	4,177
2008	3,310
2009	3,931
2010	4,623
2011	4,141
2012	4,493
2013	2,950
2014	4,518
2015	4,208
2016	5,174
2017	4,983
2018	3,894
2019	2,347
2020	4,144
2021	4,515
2022	3,733
2023	3,423
2024	4,211
2025	3,806

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	1926–2025
Completeness	100.0% of the periods in that span are held.
Continuity	Continuous: every year from 1926 to 2025 is held.
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 Chehalis and what each holds
Gauge	Measures	Values	Record
SATSOP RIVER NEAR SATSOP, WA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow	228	1929–2026
WYNOOCHEE RIVER ABOVE SAVE CREEK NEAR ABERDEEN, WA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow	209	1926–2026

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 — 17100104. 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
SATSOP RIVER NEAR SATSOP, WA	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
WYNOOCHEE RIVER ABOVE SAVE CREEK NEAR ABERDEEN, WA	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	101	yes, 20 or more
Values held	437	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-12035000.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 Chehalis gauge records, accessed 2026-09-02, hydrionis.com/waters/united-states-lower-chehalis/

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 Chehalis 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 confidence2023-12-05

Source: USGS — National Water Information System, USGS site 12035000, 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.