The monitoring network within this area

Hydrionis holds 546 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

546

Values held

1901–2026

Record spans

Gauges within the Upper Oconee 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 MIDDLE OCONEE RIVER NEAR ATHENS, GA

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1902–2025.

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	MIDDLE OCONEE RIVER NEAR ATHENS, GA (m³/s)
1902	555
1929	334
1936	402
1938	146
1939	238
1940	168
1941	85.0
1942	227
1943	252
1944	161
1945	138
1946	238
1947	221
1948	148
1950	42.5
1951	258
1953	156
1954	223
1955	159
1956	194
1957	121
1958	72.5
1959	173
1960	108
1961	345
1963	337
1964	357
1966	289
1967	270
1968	142
1969	368
1970	151
1971	209
1972	320
1973	212
1974	277
1975	271
1976	365
1977	143
1979	348
1980	200
1981	99.7
1982	235
1983	167
1985	87.5
1987	229
1988	103
1989	168
1990	388
1991	118
1992	96.0
1994	278
1995	178
1996	320
1997	219
1998	399
1999	130
2000	77.0
2001	105
2002	71.1
2003	354
2004	151
2005	187
2006	88.6
2007	115
2008	39.1
2009	139
2011	83.5
2012	65.1
2013	157
2014	157
2015	97.4
2017	111
2018	121
2019	343
2020	300
2022	132
2023	202
2024	309
2025	225

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	1902–2025
Completeness	64.5% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	14 separate periods inside 1902–2025 hold no value. The longest runs from 1903 to 1928 — 26 years with no reading. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1902 and is not continuous from it: 124 years separate the first value from the last, and 65% 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 MIDDLE OCONEE RIVER NEAR ATHENS, GA, as a depth

The year's flow spread over the land draining to this gauge, in millimetres — the same unit rainfall is measured in. 1929–2025.

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	MIDDLE OCONEE RIVER NEAR ATHENS, GA (mm)
1929	807
1930	383
1931	343
1938	334
1939	438
1940	403
1941	233
1942	416
1943	468
1944	410
1945	393
1946	502
1947	429
1948	658
1949	629
1950	314
1951	296
1952	430
1953	435
1954	258
1955	206
1956	279
1957	303
1958	322
1959	314
1960	401
1961	630
1962	459
1963	597
1964	866
1965	424
1966	572
1967	578
1968	454
1969	558
1970	319
1971	434
1972	546
1973	628
1974	446
1975	592
1976	588
1977	516
1978	369
1979	568
1980	605
1981	219
1982	456
1983	584
1984	535
1985	304
1986	219
1987	310
1988	190
1989	443
1990	570
1991	424
1992	514
1993	551
1994	559
1995	563
1996	540
1997	518
1998	680
1999	224
2000	195
2001	237
2002	292
2003	609
2004	406
2005	513
2006	285
2007	169
2008	153
2009	506
2010	491
2011	247
2012	159
2013	499
2014	341
2015	491
2016	327
2017	261
2018	549
2019	546
2020	638
2021	441
2022	408
2023	410
2024	440
2025	321

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	1929–2025
Completeness	93.8% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	One period inside 1929–2025 holds no value: 1932 to 1937, 6 years with no reading. It is drawn as a break in the line and is never interpolated across.
Continuity	The record begins in 1929 and is not continuous from it: 97 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 Oconee and what each holds
Gauge	Measures	Values	Record
MIDDLE OCONEE RIVER NEAR ATHENS, GA	catchment area, annual maximum river flow, mean river flow, mean river flow, water year	274	1902–2026
OCONEE RIVER NEAR GREENSBORO, GA	catchment area, annual maximum river flow, mean river flow, mean river flow, water year	222	1902–2026
APALACHEE RIVER NEAR BUCKHEAD, GA	catchment area, annual maximum river flow	50	1901–2026

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 — 03070101. 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
MIDDLE OCONEE RIVER NEAR ATHENS, GA	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
OCONEE RIVER NEAR GREENSBORO, GA	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
APALACHEE RIVER NEAR BUCKHEAD, GA	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 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	3	yes, 3 or more
Years spanned	126	yes, 20 or more
Values held	546	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-02217500.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 Oconee gauge records, accessed 2026-10-05, hydrionis.com/waters/united-states-upper-oconee/

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 Oconee 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 confidence2025-02-14

Source: USGS — National Water Information System, USGS site 02217500, 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.