The monitoring network within this area

Hydrionis holds 1,802 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

1,802

Values held

1912–2026

Record spans

Gauges within the South Platte Headwaters 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 SOUTH PLATTE RIVER NEAR LAKE GEORGE, CO.

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1930–1998.

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 (0 events)

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	SOUTH PLATTE RIVER NEAR LAKE GEORGE, CO. (m³/s)
1930	28.0
1932	8.66
1933	16.8
1934	7.05
1935	17.9
1936	21.1
1937	7.56
1938	17.7
1939	10.9
1940	4.79
1941	14.7
1942	19.0
1943	5.83
1944	9.29
1945	21.0
1946	14.4
1947	16.1
1948	20.3
1949	27.0
1950	8.58
1951	19.8
1952	11.6
1953	13.0
1954	10.5
1955	11.3
1956	10.8
1957	19.7
1958	12.4
1959	9.60
1960	14.5
1961	14.8
1962	10.6
1963	10.0
1964	12.6
1965	12.8
1966	7.36
1967	7.31
1968	14.7
1969	12.8
1970	85.0
1971	17.0
1972	6.99
1973	18.2
1974	5.75
1975	14.9
1976	10.00
1978	4.05
1979	17.8
1980	19.1
1981	6.57
1982	17.1
1983	11.3
1984	20.5
1985	17.3
1986	9.49
1987	15.5
1988	14.4
1989	11.0
1990	12.6
1991	5.27
1992	5.83
1993	6.20
1994	7.08
1995	28.2
1996	11.8
1997	11.2
1998	11.0

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	1930–1998
Completeness	97.1% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	2 separate periods inside 1930–1998 hold no value. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1930 and is not continuous from it: 69 years separate the first value from the last, and 97% 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 SOUTH PLATTE RIVER NEAR LAKE GEORGE, CO., as a depth

The year's flow spread over the land draining to this gauge, in millimetres — the same unit rainfall is measured in. 1930–1997.

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 (0 events)

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	SOUTH PLATTE RIVER NEAR LAKE GEORGE, CO. (mm)
1930	41.0
1931	17.0
1932	18.0
1933	15.0
1934	11.0
1935	28.0
1936	33.0
1937	11.0
1938	12.0
1940	5.00
1941	34.0
1942	34.0
1943	21.0
1944	24.0
1945	26.0
1946	19.0
1947	41.0
1948	44.0
1949	56.0
1950	18.0
1951	26.0
1952	32.0
1953	21.0
1954	48.0
1955	19.0
1956	23.0
1957	21.0
1958	23.0
1959	19.0
1960	16.0
1961	26.0
1962	26.0
1963	39.0
1964	30.0
1965	25.0
1966	9.00
1967	11.0
1968	22.0
1969	36.0
1970	77.0
1971	32.0
1972	17.0
1973	34.0
1974	15.0
1975	31.0
1976	29.0
1977	15.0
1978	11.0
1979	35.0
1980	51.0
1981	18.0
1982	37.0
1983	19.0
1984	61.0
1985	49.0
1986	40.0
1987	52.0
1988	33.0
1989	38.0
1990	42.0
1991	26.0
1992	30.0
1993	32.0
1994	35.0
1995	69.0
1996	51.0
1997	51.0

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	Derived Computed by Hydrionis
Period held	1930–1997
Completeness	98.5% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	One period inside 1930–1997 holds no value: 1939. It is drawn as a break in the line and is never interpolated across.
Continuity	The record begins in 1930 and is not continuous from it: 68 years separate the first value from the last, and 99% 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

The snow standing above this water

4 automated snow stations sit inside this drainage area, weighing the snowpack rather than measuring how deep it is.

633

Fullest snowpack recorded at Hoosier Pass, in 1995 (mm of water)

181

Thinnest, in 2026 (mm of water)

April

Month the pack is usually at its fullest

June

Month the pack has gone by, in half of years

Peak snowpack at Hoosier Pass

Water years 1981–2026. Each point is the fullest month of that snow season.

A water year runs October to September and is named for the year it ends, so the snow of one winter stays in one point. The value is the fullest month, not the fullest day: a pack that peaked sharply mid-month reads lower here than a single measurement taken at the right moment would.

View the data behind this chart

Underlying data
Period	Hoosier Pass (mm)
1981	182
1982	516
1983	328
1984	492
1985	346
1986	440
1987	452
1988	372
1989	370
1990	315
1991	309
1992	367
1993	443
1994	398
1995	633
1996	563
1997	604
1998	404
1999	513
2000	387
2001	393
2002	222
2003	374
2004	298
2005	347
2006	468
2007	434
2008	505
2009	408
2010	351
2011	520
2012	257
2013	335
2014	532
2015	509
2016	429
2017	422
2018	394
2019	535
2020	470
2021	364
2022	343
2023	328
2024	467
2025	356
2026	181

Read against the river

Hoosier Pass and SOUTH PLATTE RIVER NEAR LAKE GEORGE, CO. both sit in this drainage area, and their records overlap by 16 years. That is the span the two have in common, not a count of years both actually hold — either record may have gaps inside it. The two are shown separately rather than on one axis: millimetres of stored water and cubic metres per second are not commensurable, and a difference between them would mean nothing.

Being in the same drainage area does not put the snowpack upstream of the gauge. A subbasin is an area, and snow on one tributary can join the river below a gauge on another — so a weak relationship here may say more about which tributary was measured than about the snow.

Every gauge Hydrionis holds within this area

Gauges within the South Platte Headwaters and what each holds
Gauge	Measures	Values	Record
SOUTH PLATTE RIVER NEAR LAKE GEORGE, CO.	burned area within 50 km, catchment area, annual maximum river flow, mean river flow, mean river flow, water year	240	1929–2026
TARRYALL CREEK NEAR JEFFERSON, CO.	catchment area, annual maximum river flow	10	1912–2026

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 — 10190001. 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
SOUTH PLATTE RIVER NEAR LAKE GEORGE, CO.	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
TARRYALL CREEK NEAR JEFFERSON, CO.	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 4 of them, which makes it a full profile.

Information-gain signals held for this water body
Signal	Held	Counts
Gauges holding a real record	1	no
Years spanned	115	yes, 20 or more
Values held	1,802	yes, 1000 or more
Distinct measurements	6	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-06696000.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), South Platte Headwaters gauge records, accessed 2026-10-05, hydrionis.com/waters/united-states-south-platte-headwaters/

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 South Platte Headwaters 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 confidence1998-09-03

Source: USGS — National Water Information System, USGS site 06696000, 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.