The monitoring network within this area

Hydrionis holds 617 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

617

Values held

1915–2026

Record spans

Gauges within the Upper Frio 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 Frio Rv nr Derby, TX

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1916–2025.

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	Frio Rv nr Derby, TX (m³/s)
1916	425
1918	221
1919	974
1921	71.9
1922	300
1923	159
1924	181
1925	24.7
1926	518
1927	24.7
1928	41.9
1929	204
1930	153
1931	176
1932	6,513
1934	21.4
1935	1,934
1936	388
1937	27.8
1939	388
1941	566
1942	144
1943	139
1944	64.3
1945	183
1946	164
1947	108
1948	261
1949	195
1951	762
1952	12.3
1953	425
1954	169
1955	43.9
1956	69.1
1957	294
1958	629
1959	157
1961	507
1962	12.8
1963	21.8
1964	71.6
1965	16.0
1966	193
1967	110
1968	141
1969	13.3
1971	2,336
1973	699
1974	827
1975	73.9
1976	153
1977	54.7
1978	130
1979	242
1980	191
1981	365
1983	11.9
1984	0.878
1985	200
1986	314
1987	957
1988	45.6
1989	2.97
1990	260
1991	94.3
1993	49.3
1994	24.7
1995	68.2
1996	3.20
1997	1,597
1998	413
2000	17.5
2002	1,254
2003	385
2004	541
2006	3.79
2007	1,093
2008	4.16
2009	74.2
2010	217
2011	0.252
2012	29.7
2014	140
2015	464
2016	121
2017	26.8
2018	230
2020	1.37
2021	88.6
2023	42.8
2025	96.8

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	1916–2025
Completeness	83.6% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	18 separate periods inside 1916–2025 hold no value. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1916 and is not continuous from it: 110 years separate the first value from the last, and 84% 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 Frio Rv nr Derby, TX, as a depth

The year's flow spread over the land draining to this gauge, in millimetres — the same unit rainfall is measured in. 1916–2025.

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	Frio Rv nr Derby, TX (mm)
1916	12.0
1917	0
1918	10.0
1919	89.0
1920	3.00
1921	3.00
1922	18.0
1923	6.00
1924	4.00
1925	1.00
1926	12.0
1927	1.00
1928	2.00
1929	8.00
1930	7.00
1931	12.0
1932	96.0
1933	2.00
1934	2.00
1935	110
1936	23.0
1937	4.00
1938	3.00
1939	8.00
1940	2.00
1941	21.0
1942	10.0
1943	3.00
1944	7.00
1945	6.00
1946	8.00
1947	3.00
1948	4.00
1949	10.0
1950	0
1951	9.00
1952	0
1953	12.0
1954	3.00
1955	1.00
1956	1.00
1957	32.0
1958	38.0
1959	11.0
1960	1.00
1961	11.0
1962	1.00
1963	0
1964	3.00
1965	1.00
1966	4.00
1967	7.00
1968	9.00
1969	8.00
1970	4.00
1971	60.0
1972	8.00
1973	43.0
1974	21.0
1975	15.0
1976	28.0
1977	21.0
1978	7.00
1979	23.0
1980	12.0
1981	39.0
1982	5.00
1983	3.00
1984	4.00
1985	9.00
1986	12.0
1990	7.00
1993	7.00
1994	4.00
1995	4.00
1996	3.00
1999	4.00
2000	8.00
2001	5.00
2002	71.0
2003	19.0
2004	43.0
2005	11.0
2006	2.00
2007	46.0
2008	4.00
2009	1.00
2010	6.00
2011	0
2012	1.00
2013	0
2014	2.00
2015	13.0
2016	8.00
2017	1.00
2018	32.0
2019	2.00
2020	1.00
2021	3.00
2022	0
2023	1.00
2024	0
2025	2.00

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	1916–2025
Completeness	93.6% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	3 separate periods inside 1916–2025 hold no value. The longest runs from 1987 to 1989 — 3 years with no reading. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1916 and is not continuous from it: 110 years separate the first value from the last, and 94% 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 Upper Frio and what each holds
Gauge	Measures	Values	Record
Frio Rv nr Derby, TX	catchment area, annual maximum river flow, mean river flow, mean river flow, water year	317	1915–2026
Frio Rv at Concan, TX	catchment area, annual maximum river flow, mean river flow, mean river flow, water year	300	1923–2026

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 — 12110106. 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
Frio Rv nr Derby, TX	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
Frio Rv at Concan, TX	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	112	yes, 20 or more
Values held	617	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-08205500.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), Upper Frio gauge records, accessed 2026-10-05, hydrionis.com/waters/united-states-upper-frio/

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 Upper Frio 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 confidence2025-07-17

Source: USGS — National Water Information System, USGS site 08205500, 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.