HydrionisGlobal Water Intelligence
HUC8 subbasin

Trinity

2 monitoring stations within this area in United States, holding 411 values between 1912 and 2026. A United States federal hydrologic unit at the eight-digit subbasin level — a drainage area, not a river. Many subbasins take the name of the largest river within them, and the gauges below are anywhere inside the area, including on tributaries.

United StatesHUC8 subbasin

The monitoring network within this area

Hydrionis holds 411 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.

2
Gauges
411
Values held
1912–2026
Record spans
Gauges within the Trinity huc8 subbasin
2 monitoring points, positioned as the publisher records them.
Gauges within the Trinity huc8 subbasinTRINITY R A LEWISTON CA, TRINITY R A HOOPA CATRINITY R A LEWISTON CATRINITY R A HOOPA CA

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 TRINITY R A LEWISTON CA
The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1912–2025.
Shading marks when something was recorded, not what caused the line.
Largest measured flow of each year at TRINITY R A LEWISTON CALargest measured flow of each year at TRINITY R A LEWISTON CA: TRINITY R A LEWISTON CA in m³/s, from 1912 to 2025.Hurricane Katrina water and sanitation collapse01,0002,000m³/s19121928194419601974198920022015

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.

EventTypePeriodStandingAuthority
Hurricane Katrina water and sanitation collapseFlood2005-08-29 – 2005-09-30Documented 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
PeriodTRINITY R A LEWISTON CA (m³/s)
1912328
1914762
1915651
1916665
1917300
1918228
1919617
192086.6
1922218
1923128
1924253
1925566
1926484
1928813
1929133
1931147
1932250
1933244
1934351
1935254
1936467
1937382
1939124
19401,141
1941920
1943208
1944157
1945255
1946238
19481,124
1949445
1950180
1952552
1953507
1954558
1955195
1957665
19581,062
1959600
1960507
196247.3
1963360
196416.1
196511.1
196629.2
196774.8
19687.73
196941.1
1970184
197124.5
19727.82
197318.2
1974408
197564.0
197630.0
197821.4
197926.1
198081.0
1981138
1983249
1984183
198524.4
1986179
198723.4
198818.0
198956.1
199019.6
199181.0
1992186
199392.6
199446.2
1995200
1996181
1997197
1998175
199956.6
2000154
200160.6
2002186
200378.7
2004180
2005216
2006294
2007136
2008195
2009131
2010212
2011348
2012175
2013130
201498.0
2015250
2016272
2017340
201857.8
2019306
2020112
2021115
2022171
2023297
2024249
2025247

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 existMeasured
Period held1912–2025
Completeness89.5% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps
  • 12 separate periods inside 1912–2025 hold no value. They are drawn as breaks in the line and are never interpolated across.
ContinuityThe record begins in 1912 and is not continuous from it: 114 years separate the first value from the last, and 89% of the years between them are held. The span is not the record.
Last read from the publisher2026-08-31
RedistributionPermitted by the upstream licences
Commercial reusePermitted by the upstream licences. No Hydrionis access tier can widen this.
MethodologyHow 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 TRINITY R A LEWISTON 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. 1962–2024.
Shading marks when something was recorded, not what caused the line.
Water leaving the catchment above TRINITY R A LEWISTON CA, as a depthWater leaving the catchment above TRINITY R A LEWISTON CA, as a depth: TRINITY R A LEWISTON CA in mm, from 1962 to 2024.Hurricane Katrina water and sanitation collapse02505007501,000mm19621970197819861994200220102018TRINITY R A LEWISTON CA 1962: 103 mmTRINITY R A LEWISTON CA 1963: 576 mmTRINITY R A LEWISTON CA 1964: 99.0 mmTRINITY R A LEWISTON CA 1965: 85.0 mmTRINITY R A LEWISTON CA 1966: 101 mmTRINITY R A LEWISTON CA 1967: 157 mmTRINITY R A LEWISTON CA 1968: 84.0 mmTRINITY R A LEWISTON CA 1969: 103 mmTRINITY R A LEWISTON CA 1970: 141 mmTRINITY R A LEWISTON CA 1971: 120 mmTRINITY R A LEWISTON CA 1972: 82.0 mmTRINITY R A LEWISTON CA 1973: 88.0 mmTRINITY R A LEWISTON CA 1974: 468 mmTRINITY R A LEWISTON CA 1975: 182 mmTRINITY R A LEWISTON CA 1976: 82.0 mmTRINITY R A LEWISTON CA 1977: 80.0 mmTRINITY R A LEWISTON CA 1978: 130 mmTRINITY R A LEWISTON CA 1979: 149 mmTRINITY R A LEWISTON CA 1980: 221 mmTRINITY R A LEWISTON CA 1981: 236 mmTRINITY R A LEWISTON CA 1982: 264 mmTRINITY R A LEWISTON CA 1983: 948 mmTRINITY R A LEWISTON CA 1984: 274 mmTRINITY R A LEWISTON CA 1985: 168 mmTRINITY R A LEWISTON CA 1986: 327 mmTRINITY R A LEWISTON CA 1987: 204 mmTRINITY R A LEWISTON CA 1988: 169 mmTRINITY R A LEWISTON CA 1989: 221 mmTRINITY R A LEWISTON CA 1990: 152 mmTRINITY R A LEWISTON CA 1991: 186 mmTRINITY R A LEWISTON CA 1992: 236 mmTRINITY R A LEWISTON CA 1993: 238 mmTRINITY R A LEWISTON CA 1994: 237 mmTRINITY R A LEWISTON CA 1995: 479 mmTRINITY R A LEWISTON CA 1996: 359 mmTRINITY R A LEWISTON CA 1997: 574 mmTRINITY R A LEWISTON CA 1998: 897 mmTRINITY R A LEWISTON CA 1999: 268 mmTRINITY R A LEWISTON CA 2000: 373 mmTRINITY R A LEWISTON CA 2001: 258 mmTRINITY R A LEWISTON CA 2002: 314 mmTRINITY R A LEWISTON CA 2003: 371 mmTRINITY R A LEWISTON CA 2004: 508 mmTRINITY R A LEWISTON CA 2005: 439 mmTRINITY R A LEWISTON CA 2006: 801 mmTRINITY R A LEWISTON CA 2007: 305 mmTRINITY R A LEWISTON CA 2008: 430 mmTRINITY R A LEWISTON CA 2009: 302 mmTRINITY R A LEWISTON CA 2010: 434 mmTRINITY R A LEWISTON CA 2011: 487 mmTRINITY R A LEWISTON CA 2012: 456 mmTRINITY R A LEWISTON CA 2013: 318 mmTRINITY R A LEWISTON CA 2014: 288 mmTRINITY R A LEWISTON CA 2015: 339 mmTRINITY R A LEWISTON CA 2016: 494 mmTRINITY R A LEWISTON CA 2017: 575 mmTRINITY R A LEWISTON CA 2018: 271 mmTRINITY R A LEWISTON CA 2019: 470 mmTRINITY R A LEWISTON CA 2020: 250 mmTRINITY R A LEWISTON CA 2021: 257 mmTRINITY R A LEWISTON CA 2022: 260 mmTRINITY R A LEWISTON CA 2023: 466 mmTRINITY R A LEWISTON CA 2024: 502 mm

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.

EventTypePeriodStandingAuthority
Hurricane Katrina water and sanitation collapseFlood2005-08-29 – 2005-09-30Documented 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
PeriodTRINITY R A LEWISTON CA (mm)
1962103
1963576
196499.0
196585.0
1966101
1967157
196884.0
1969103
1970141
1971120
197282.0
197388.0
1974468
1975182
197682.0
197780.0
1978130
1979149
1980221
1981236
1982264
1983948
1984274
1985168
1986327
1987204
1988169
1989221
1990152
1991186
1992236
1993238
1994237
1995479
1996359
1997574
1998897
1999268
2000373
2001258
2002314
2003371
2004508
2005439
2006801
2007305
2008430
2009302
2010434
2011487
2012456
2013318
2014288
2015339
2016494
2017575
2018271
2019470
2020250
2021257
2022260
2023466
2024502

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 existDerived Computed by Hydrionis
Period held1962–2024
Completeness100.0% of the periods in that span are held.
ContinuityContinuous: every year from 1962 to 2024 is held.
Last read from the publisher2026-08-24
RedistributionPermitted by the upstream licences
Commercial reusePermitted by the upstream licences. No Hydrionis access tier can widen this.
MethodologyHow this was produced

Every gauge Hydrionis holds within this area

GaugeMeasuresValuesRecord
TRINITY R A LEWISTON CAburned area within 50 km, catchment area, annual maximum river flow, mean river flow2141912–2026
TRINITY R A HOOPA CAburned area within 50 km, catchment area, annual maximum river flow, mean river flow1971912–2026

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 — 18010211. 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.

GaugeEvidenceEstablished
TRINITY R A LEWISTON CAStated 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/42026-08-26
TRINITY R A HOOPA CAStated 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/42026-08-26

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.

SignalHeldCounts
Gauges holding a real record2no
Years spanned115yes, 20 or more
Values held411no
Distinct measurements4yes, 2 or more
Publishers measuring it2yes, 2 or more
Official identifiers1recorded, not counted

Use this data

Use this data

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), Trinity gauge records, accessed 2026-09-02, hydrionis.com/waters/united-states-trinity/

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 Trinity 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 confidence2025-04-16

Source: USGS — National Water Information System, USGS site 11525500, 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.

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