HydrionisGlobal Water Intelligence
Monitored reservoir

Lake Ellsworth Near Elgin, OK

United States Geological Survey reservoir gauge 07308990 in OK, with published storage from 1995.

Storage record07308990

Storage now, against this reservoir's own record

19.96 Mm³
Stored, September 2026
3rd
Percentile among 31 Seps on record
-65.3%
Against the Sep 1991–2020 average
-57.6%
Change over the 12 months to 2026-09

Storage in September 2026 was lower than almost every other Sep on record, ranked against 31 other Seps held for this reservoir.

Storage, 1995–2026

Monthly mean storage
372 monthly values, 1995 to 2026
Monthly mean storageMonthly mean storage: Lake Ellsworth Near Elgin, OK in Mm³, from 1995.75 to 2026.6666666666667.0255075100Mm³1995.751999.66666666666672003.58333333333332007.52011.41666666666672015.33333333333332019.252023.1666666666667Year

Monthly means of the publisher's daily record. Volume, not percentage of capacity — see below for why.

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
240 of 372 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 372 would be longer than this page and unusable with a screen reader.
PeriodLake Ellsworth Near Elgin, OK (Mm³)
October 199574.4
December 199572.7
January 199673.5
March 199672.8
April 199672.5
June 199666.3
July 199671.1
September 199683.6
October 199675.3
December 199679.3
February 199782.2
March 199781.3
May 199778.5
June 199777.7
August 199778.5
September 199770.9
November 199775.1
December 199778.7
February 199887.4
March 199886.6
May 199873.4
July 199867.4
August 199860.5
October 199849.0
November 199853.3
January 199955.2
February 199962.0
April 199974.1
May 199973.6
July 199982.9
September 199971.0
October 199966.5
December 199962.7
January 200063.3
March 200068.0
April 200073.6
June 200076.1
July 200083.6
September 200072.2
November 200086.9
December 200083.5
February 200185.8
March 200181.2
May 200174.8
June 200180.8
August 200172.7
September 200169.8
November 200158.3
January 200250.6
February 200248.6
April 200247.6
May 200250.3
July 200244.4
August 200238.1
October 200230.2
November 200234.2
January 200334.3
February 200332.8
April 200332.0
June 200334.8
July 200336.3
September 200328.0
October 200324.5
December 200319.6
January 200416.6
March 200418.9
April 200419.4
June 200416.7
August 200414.4
September 200411.7
November 200432.5
December 200446.5
February 200555.6
March 200558.2
May 200557.7
June 200556.7
August 200547.3
October 200543.2
November 200539.7
January 200632.6
February 200630.0
April 200627.0
May 200627.9
July 200624.5
August 200621.6
October 200623.9
November 200622.3
January 200722.7
March 200725.2
April 200744.1
June 200782.6
July 200778.4
September 200773.8
October 200774.4
December 200774.7
January 200874.3
March 200874.6
May 200874.1
June 200873.5
August 200869.6
September 200866.8
November 200856.1
December 200851.2
February 200945.0
March 200943.1
May 200966.3
July 200970.2
August 200972.4
October 200966.6
November 200969.6
January 201068.3
February 201074.5
April 201074.7
May 201075.1
July 201075.2
September 201066.1
October 201062.8
December 201061.8
January 201159.3
March 201156.0
April 201150.7
June 201151.9
July 201144.3
September 201132.6
October 201128.9
December 201125.8
February 201225.0
March 201227.8
May 201250.5
June 201251.2
August 201243.4
September 201239.0
November 201231.6
December 201228.5
February 201325.5
April 201336.6
May 201349.7
July 201356.8
August 201374.8
October 201367.7
November 201365.5
January 201462.3
February 201458.1
April 201454.4
June 201452.2
July 201451.1
September 201439.9
October 201434.7
December 201429.2
January 201530.1
March 201529.0
April 201527.7
June 201580.5
August 201574.9
September 201569.6
November 201563.6
December 201571.3
February 201682.5
March 201682.3
May 201682.2
June 201683.7
August 201677.1
September 201674.9
November 201667.0
January 201763.7
February 201767.5
April 201777.3
May 201776.0
July 201772.5
August 201774.7
October 201777.7
November 201776.1
January 201873.8
March 201873.4
April 201872.5
June 201872.0
July 201867.2
September 201863.0
October 201875.2
December 201876.6
January 201974.5
March 201975.4
May 201975.9
June 201972.9
August 201964.4
September 201963.2
November 201956.2
December 201955.3
February 202058.8
March 202066.3
May 202074.7
June 202074.6
August 202068.2
October 202071.4
November 202074.8
January 202174.6
February 202175.6
April 202173.8
May 202175.0
July 202175.6
August 202173.4
October 202170.7
December 202165.8
January 202263.9
March 202258.3
April 202258.5
June 202275.0
July 202270.5
September 202262.3
October 202257.9
December 202263.4
February 202365.3
March 202366.0
May 202365.9
June 202369.4
August 202369.6
September 202365.0
November 202355.9
December 202355.3
February 202460.6
April 202465.3
May 202475.6
July 202470.0
August 202466.0
October 202456.5
November 202471.6
January 202573.2
February 202572.6
April 202576.0
May 202571.1
July 202551.4
September 202547.1
October 202544.4
December 202540.5
January 202639.2
March 202634.5
April 202631.8
June 202628.5
July 202626.6
September 202620.0

The reservoir's year

Seasonal storage profile
Each calendar month's reference average, against the most recent year
Seasonal storage profileSeasonal storage profile: 1991–2020 average, Most recent 12 months in Mm³, from 1 to 12.020406080Mm³123456789101112Month1991–2020 average 1: 55.7 Mm³1991–2020 average 2: 56.3 Mm³1991–2020 average 3: 57.1 Mm³1991–2020 average 4: 58.7 Mm³1991–2020 average 5: 62.7 Mm³1991–2020 average 6: 64.1 Mm³1991–2020 average 7: 62.9 Mm³1991–2020 average 8: 60.2 Mm³1991–2020 average 9: 57.5 Mm³1991–2020 average 10: 56.6 Mm³1991–2020 average 11: 56.4 Mm³1991–2020 average 12: 56.4 Mm³Most recent 12 months 1: 39.2 Mm³Most recent 12 months 2: 38.0 Mm³Most recent 12 months 3: 34.5 Mm³Most recent 12 months 4: 31.8 Mm³Most recent 12 months 5: 29.9 Mm³Most recent 12 months 6: 28.5 Mm³Most recent 12 months 7: 26.6 Mm³Most recent 12 months 8: 22.9 Mm³Most recent 12 months 9: 20.0 Mm³Most recent 12 months 10: 44.4 Mm³Most recent 12 months 11: 41.2 Mm³Most recent 12 months 12: 40.5 Mm³
  • 1991–2020 average
  • Most recent 12 months

Twelve separate averages, one per calendar month. A January average describes Januaries only. Months are plotted 1–12.

View the data behind this chart
Underlying data
Period1991–2020 average (Mm³)Most recent 12 months (Mm³)
Jan55.739.2
Feb56.338.0
Mar57.134.5
Apr58.731.8
May62.729.9
Jun64.128.5
Jul62.926.6
Aug60.222.9
Sep57.520.0
Oct56.644.4
Nov56.441.2
Dec56.440.5

Why this page shows a volume and not a percentage

Rate and persistence

-2.26 Mm³
Mean drawdown per month over 12 months
6 of 24
Recent months below the 20th percentile for their own month

Rates are computed only across an unbroken run of months, so a rate is never divided by a period in which some of the change was not observed. Percentile counts compare each month with the same calendar month in every other year held.

Location

Lake Ellsworth Near Elgin, OK
Gauge location
Lake Ellsworth Near Elgin, OKLake Ellsworth Near Elgin, OK — 19.96 Mm³Lake Ellsworth Near Elgin, OK — 19.96 Mm³

About this data

About this data

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 held1995–2026
Completeness96.9% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps
  • Storage is a managed quantity. A falling line can be a rule curve, a scheduled release or a transfer to another system rather than a shortage of water, and nothing here distinguishes them.
  • No capacity figure on a stated basis is held for this reservoir, so no percentage of capacity is computed.
Continuity97% of the months between 1995 and 2026 are held. Monthly means of the publisher's own daily record.
Last read from the publisher2026-10-01
RedistributionPermitted by the upstream licences
Commercial reusePermitted by the upstream licences. No Hydrionis access tier can widen this.
MethodologyHow this was produced

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), Lake Ellsworth Near Elgin, OK reservoir records, accessed 2026-10-05, hydrionis.com/reservoirs/reservoir-usgs-07308990/

Cite Hydrionis where you rely on the compilation, the normalisation, the eligibility judgements or a chart. Where you use an unmodified published value, the publisher’s attribution is the one that is required; crediting Hydrionis as well is welcome and is not something Hydrionis can require of you.

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 Lake Ellsworth Near Elgin, OK record 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 this comes from

372 monthly observations 1995–2026 Mm³
Spatially aggregatedHigh confidenceSeptember 2026

Source: USGS — National Water Information System, 07308990. Licence: Open.

Method: Monthly mean of daily reservoir storage published by the USGS in acre-feet and converted to millions of cubic metres. Months with fewer than 20 days of record are not published rather than averaged from a partial month.

Reservoir storage is managed as well as observed: a drawdown may reflect an operating rule, flood-control rule curve or scheduled release rather than a shortage. Compare a month against the same month in other years, and do not read a fall as a supply signal without knowing the operating regime.

Retrieved 1 October 2026.

Monthly mean of daily reservoir storage published by the USGS in acre-feet and converted to millions of cubic metres. Months with fewer than 20 days of record are not published rather than averaged from a partial month.

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