HydrionisGlobal Water Intelligence
Monitored reservoir

Big Sandy Reservoir Near Farson, WY

United States Geological Survey reservoir gauge 09213700 in WY, with published storage from 1987.

Storage record09213700

Storage now, against this reservoir's own record

29.13 Mm³
Stored, November 2024
84th
Percentile among 38 Novs on record
+61.5%
Against the Nov 1991–2020 average
-36.4%
Change over the 12 months to 2024-11

Storage in November 2024 was higher than most Novs on record, ranked against 38 other Novs held for this reservoir.

Storage, 1987–2024

Monthly mean storage
447 monthly values, 1987 to 2024
Monthly mean storageMonthly mean storage: Big Sandy Reservoir Near Farson, WY in Mm³, from 1987.3333333333333 to 2024.8333333333333.020406080Mm³1987.333333333333319921996.66666666666672001.52006.16666666666672010.83333333333332015.66666666666672020.3333333333333Year

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 447 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 447 would be longer than this page and unusable with a screen reader.
PeriodBig Sandy Reservoir Near Farson, WY (Mm³)
May 198747.4
July 198742.0
September 198726.8
November 198728.4
December 198729.1
February 198829.5
April 198833.5
June 198831.8
August 19887.27
October 19881.79
December 19882.81
February 19892.91
March 19894.01
May 198915.1
July 198917.1
September 19897.38
November 198910.1
January 199011.4
March 199013.1
April 199016.8
June 199031.9
August 199023.1
October 199015.3
December 199018.2
February 199119.1
April 199123.7
June 199145.5
July 199135.9
September 199118.7
November 199120.7
January 199222.8
March 199225.9
May 199232.9
July 199221.9
August 199211.3
October 19923.33
December 19925.47
February 19937.53
April 199311.8
June 199336.7
August 199336.5
October 199329.1
November 199330.3
January 199431.6
March 199433.7
May 199443.6
July 199422.9
September 19942.53
November 19944.95
December 19945.98
February 19958.10
April 199517.0
June 199544.6
August 199539.1
October 199530.6
December 199533.7
February 199635.6
March 199637.2
May 199640.7
July 199643.6
September 199614.4
November 199615.8
January 199718.8
March 199725.5
April 199735.7
June 199749.4
August 199736.7
October 199724.8
December 199727.2
February 199829.1
April 199833.6
May 199839.2
July 199847.0
September 199832.5
November 199835.8
January 199937.9
March 199943.0
May 199948.3
July 199945.5
August 199931.7
October 199921.0
December 199923.0
March 200025.9
May 200034.9
August 200011.9
October 20001.06
November 20003.69
January 20016.00
March 20018.19
May 200120.7
July 200111.4
September 20011.09
November 20012.70
January 20024.09
February 20024.43
April 20027.99
June 200222.9
August 20023.05
October 20023.05
December 20024.84
February 20036.14
March 20037.60
May 200315.0
July 200319.3
September 20033.98
November 20035.42
January 20046.75
March 20048.48
May 200421.5
June 200428.1
August 200424.3
October 200420.6
December 200425.2
February 200527.6
April 200534.8
June 200548.3
July 200546.2
September 200530.3
November 200529.8
January 200631.4
March 200633.5
May 200642.7
July 200635.9
September 200611.5
October 200612.6
December 200615.5
February 200716.7
April 200721.9
June 200733.9
August 20079.83
October 20077.54
November 200710.1
January 200811.8
March 200813.4
May 200822.4
July 200835.6
September 200810.6
November 200812.8
January 200913.9
February 200914.6
April 200918.1
June 200943.1
August 200934.5
October 200920.8
December 200922.9
February 201023.0
March 201024.6
May 201031.3
July 201042.3
September 201018.6
November 201018.9
January 201121.3
March 201123.1
May 201129.6
June 201141.4
August 201137.1
October 201124.1
December 201126.5
February 201227.5
April 201233.4
June 201243.0
July 201230.8
September 20125.92
November 20126.97
January 20138.70
March 201310.4
May 201319.5
July 201316.1
September 20134.27
October 20137.34
December 201310.5
February 201411.6
April 201415.8
June 201435.9
August 201423.6
December 201424.6
January 201526.0
March 201528.7
May 201539.7
July 201541.8
September 201522.2
November 201522.7
January 201623.9
February 201624.5
April 201628.7
June 201646.8
August 201626.3
October 201619.5
December 201626.3
February 201729.8
April 201733.9
May 201742.2
July 201745.7
September 201730.3
November 201734.6
January 201837.4
March 201839.8
May 201846.6
June 201846.6
August 201827.8
October 201816.4
December 201818.3
February 201919.9
April 201924.2
June 201942.0
August 201932.6
September 201922.7
November 201926.0
January 202027.5
March 202029.2
May 202037.2
July 202034.9
September 202010.1
October 20208.97
December 20209.85
February 20219.84
April 202113.0
June 202124.5
August 20212.55
October 20213.61
December 20217.17
January 20227.79
March 20229.00
May 202216.1
July 202226.7
September 20224.13
November 20226.49
January 20238.67
February 20239.82
April 202312.8
June 202357.8
August 202351.3
October 202344.1
December 202346.9
February 202448.9
April 202453.3
May 202459.9
July 202453.6
September 202430.2
November 202429.1

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: 20.0 Mm³1991–2020 average 2: 21.0 Mm³1991–2020 average 3: 22.7 Mm³1991–2020 average 4: 26.0 Mm³1991–2020 average 5: 32.2 Mm³1991–2020 average 6: 39.5 Mm³1991–2020 average 7: 35.5 Mm³1991–2020 average 8: 24.0 Mm³1991–2020 average 9: 15.7 Mm³1991–2020 average 10: 16.2 Mm³1991–2020 average 11: 18.0 Mm³1991–2020 average 12: 19.1 Mm³Most recent 12 months 1: 47.8 Mm³Most recent 12 months 2: 48.9 Mm³Most recent 12 months 3: 50.1 Mm³Most recent 12 months 4: 53.3 Mm³Most recent 12 months 5: 59.9 Mm³Most recent 12 months 6: 62.2 Mm³Most recent 12 months 7: 53.6 Mm³Most recent 12 months 8: 40.4 Mm³Most recent 12 months 9: 30.2 Mm³Most recent 12 months 10: 28.4 Mm³Most recent 12 months 11: 29.1 Mm³Most recent 12 months 12: 46.9 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)
Jan20.047.8
Feb21.048.9
Mar22.750.1
Apr26.053.3
May32.259.9
Jun39.562.2
Jul35.553.6
Aug24.040.4
Sep15.730.2
Oct16.228.4
Nov18.029.1
Dec19.146.9

Why this page shows a volume and not a percentage

Rate and persistence

-1.39 Mm³
Mean drawdown per month over 12 months
1 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

Big Sandy Reservoir Near Farson, WY
Gauge location
Big Sandy Reservoir Near Farson, WYBig Sandy Reservoir Near Farson, WY — 29.13 Mm³Big Sandy Reservoir Near Farson, WY — 29.13 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 held1987–2024
Completeness98.0% 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.
Continuity98% of the months between 1987 and 2024 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), Big Sandy Reservoir Near Farson, WY reservoir records, accessed 2026-10-05, hydrionis.com/reservoirs/reservoir-usgs-09213700/

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 Big Sandy Reservoir Near Farson, WY 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

447 monthly observations 1987–2024 Mm³
Spatially aggregatedHigh confidenceNovember 2024

Source: USGS — National Water Information System, 09213700. 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.

Hydrionis would like to measure which pages are read, using HEKNO Analytics, which HEKNO Ltd runs itself, and Google Analytics. Google Analytics stores an identifier on your device, so we only do this if you agree. Nothing is measured if you decline, and the site works identically either way. See cookies for what is set and how to change your mind.