HydrionisGlobal Water Intelligence
Monitored reservoir

Gerber Reservoir

Gerber Reservoir is a federal reservoir operated by the United States Bureau of Reclamation in its Mid-Pacific region, with published operating records from 1986.

Storage recordGerber Reservoir and Dam (GER)

Storage now, against this reservoir's own record

38.92 Mm³
Stored, September 2026
53rd
Percentile among 39 Seps on record
-13.9%
Against the Sep 1991–2020 average
-38.1%
Change over the 12 months to 2026-09

Storage in September 2026 was around the middle of the Sep record, ranked against 39 other Seps held for this reservoir.

Storage, 1986–2026

Monthly mean storage
402 monthly values, 1986 to 2026
Monthly mean storageMonthly mean storage: Gerber Reservoir in Mm³, from 1986.1666666666667 to 2026.6666666666667.050100Mm³1986.16666666666671996.33333333333332001.7520062010.252014.52018.752023Year

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 402 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 402 would be longer than this page and unusable with a screen reader.
PeriodGerber Reservoir (Mm³)
March 1986117
May 1986111
June 1986101
August 198676.2
May 198775.0
June 198765.3
August 198745.8
April 198849.3
May 198847.9
July 198829.2
September 19889.49
May 198983.1
July 198961.4
September 198940.3
May 199051.1
July 199032.8
September 199013.4
June 199111.7
July 19915.32
May 199399.1
July 199383.7
August 199373.3
May 199458.2
July 199438.3
August 199426.9
April 1995115
June 1995111
July 1995103
September 199578.8
March 1996115
April 1996119
June 1996112
August 199691.4
September 199680.4
February 1997112
May 1997113
June 1997104
August 199782.3
March 1998114
April 1998118
June 1998118
August 199898.3
September 199887.6
April 1999100
June 1999105
August 199981.4
September 199971.3
November 199965.0
January 200068.6
February 200078.1
April 2000110
June 2000102
July 200090.1
September 200068.8
November 200063.5
December 200063.9
February 200164.4
April 200173.6
May 200169.1
July 200146.5
September 200126.1
October 200123.1
December 200124.5
February 200241.2
March 200252.4
May 200267.2
July 200244.6
August 200232.6
October 200217.5
December 200217.5
January 200324.2
March 200334.7
May 200362.3
June 200355.0
August 200331.1
October 200317.4
December 200318.1
January 200420.9
March 200450.4
May 200456.5
June 200448.0
August 200425.3
October 200411.8
November 200411.6
January 200517.3
March 200525.3
April 200531.2
June 200553.1
August 200530.5
September 200519.6
November 200517.3
January 200670.0
February 200688.2
April 2006122
June 2006108
July 200696.8
September 200673.9
November 200668.6
December 200672.3
February 200779.6
April 2007103
May 200799.7
July 200777.6
September 200755.7
October 200751.3
December 200751.3
February 200854.0
April 200894.8
May 200896.3
July 200881.1
September 200859.5
October 200854.5
December 200854.1
February 200956.2
March 200965.1
May 200969.1
July 200953.5
August 200942.4
October 200927.4
December 200927.2
January 201029.2
March 201037.6
May 201045.4
June 201040.9
August 201019.6
October 20106.68
November 20106.81
January 201125.6
March 201148.3
April 201178.5
June 201188.7
August 201167.1
September 201157.0
November 201152.0
January 201252.3
March 201260.8
April 201275.4
June 201267.8
August 201246.2
September 201236.3
November 201231.8
January 201339.6
February 201343.5
April 201357.4
June 201343.9
July 201334.2
September 201316.0
November 201312.5
December 201312.5
February 201414.4
April 201423.8
May 201419.7
July 20143.74
September 20141.74
October 20141.61
December 20146.13
February 201518.2
March 201519.4
May 201514.7
July 20152.76
August 20152.13
October 20151.57
December 20152.06
January 20167.49
March 201651.7
May 201655.9
July 201637.8
August 201627.6
October 201614.9
December 201619.7
January 201724.6
March 201784.0
May 2017116
June 2017106
August 201784.5
October 201770.9
November 201771.3
January 201874.0
March 201886.6
April 2018103
June 201893.9
August 201873.4
September 201864.6
November 201859.6
January 201964.3
February 201973.0
April 2019118
June 2019106
July 201994.9
September 201974.7
November 201971.9
December 201973.0
February 202084.3
April 202086.7
May 202080.4
July 202061.3
September 202041.3
November 202032.2
December 202031.2
February 202132.5
April 202135.2
May 202129.3
July 202111.8
September 20212.61
October 20212.52
December 20213.03
February 20226.45
March 202212.7
May 202217.9
July 20223.90
August 20222.09
October 20221.59
December 20221.81
January 20239.07
March 202314.9
May 202359.4
June 202351.3
August 202329.6
October 202318.8
November 202318.5
January 202421.0
March 202439.4
April 202450.0
June 202440.4
August 202418.5
October 20247.83
November 20248.41
January 202535.5
March 202567.9
April 2025104
June 202595.6
August 202572.1
September 202562.9
November 202560.0
January 202670.7
February 202672.9
April 202679.8
June 202666.7
July 202656.7
September 202638.9

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 12.0255075100Mm³123456789101112Month1991–2020 average 1: 46.2 Mm³1991–2020 average 2: 55.7 Mm³1991–2020 average 3: 65.8 Mm³1991–2020 average 4: 81.7 Mm³1991–2020 average 5: 80.0 Mm³1991–2020 average 6: 73.0 Mm³1991–2020 average 7: 62.8 Mm³1991–2020 average 8: 54.3 Mm³1991–2020 average 9: 45.2 Mm³1991–2020 average 10: 35.3 Mm³1991–2020 average 11: 35.1 Mm³1991–2020 average 12: 37.2 Mm³Most recent 12 months 1: 70.7 Mm³Most recent 12 months 2: 72.9 Mm³Most recent 12 months 3: 80.2 Mm³Most recent 12 months 4: 79.8 Mm³Most recent 12 months 5: 74.2 Mm³Most recent 12 months 6: 66.7 Mm³Most recent 12 months 7: 56.7 Mm³Most recent 12 months 8: 46.2 Mm³Most recent 12 months 9: 38.9 Mm³Most recent 12 months 10: 60.1 Mm³Most recent 12 months 11: 60.0 Mm³Most recent 12 months 12: 61.6 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)
Jan46.270.7
Feb55.772.9
Mar65.880.2
Apr81.779.8
May80.074.2
Jun73.066.7
Jul62.856.7
Aug54.346.2
Sep45.238.9
Oct35.360.1
Nov35.160.0
Dec37.261.6

Why this page shows a volume and not a percentage

Water level

Monthly mean water surface elevation
402 monthly values
Monthly mean water surface elevationMonthly mean water surface elevation: Gerber Reservoir in m, from 1986.1666666666667 to 2026.6666666666667.1,4601,4651,4701,475m1986.16666666666671996.33333333333332001.7520062010.252014.52018.752023Year

An elevation above a datum, not a depth of water and not a distance below the crest. Levels at different reservoirs are measured against different datums and must not be read against one another; this line is comparable only with its own history. Elevation and volume are not proportional either — a metre near the bottom of a reservoir holds far less water than a metre near the top, because the surface area grows with height.

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 402 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 402 would be longer than this page and unusable with a screen reader.
PeriodGerber Reservoir (m)
1986.16666666666671,474
1986.33333333333331,474
1986.41666666666671,473
1986.58333333333331,471
1987.33333333333331,471
1987.41666666666671,470
1987.58333333333331,469
1988.251,469
1988.33333333333331,469
1988.51,467
1988.66666666666671,464
1989.33333333333331,472
1989.51,470
1989.66666666666671,468
1990.33333333333331,469
1990.51,467
1990.66666666666671,465
1991.41666666666671,465
1991.51,464
1993.33333333333331,473
1993.51,472
1993.58333333333331,471
1994.33333333333331,470
1994.51,468
1994.58333333333331,467
1995.251,474
1995.41666666666671,474
1995.51,473
1995.66666666666671,471
1996.16666666666671,474
1996.251,474
1996.41666666666671,474
1996.58333333333331,472
1996.66666666666671,471
1997.08333333333331,474
1997.33333333333331,474
1997.41666666666671,473
1997.58333333333331,471
1998.16666666666671,474
1998.251,474
1998.41666666666671,474
1998.58333333333331,473
1998.66666666666671,472
1999.251,473
1999.41666666666671,473
1999.58333333333331,471
1999.66666666666671,471
1999.83333333333331,470
20001,470
2000.08333333333331,471
2000.251,473
2000.41666666666671,473
2000.51,472
2000.66666666666671,470
2000.83333333333331,470
2000.91666666666671,470
2001.08333333333331,470
2001.251,471
2001.33333333333331,471
2001.51,469
2001.66666666666671,467
2001.751,466
2001.91666666666671,466
2002.08333333333331,468
2002.16666666666671,469
2002.33333333333331,470
2002.51,468
2002.58333333333331,467
2002.751,466
2002.91666666666671,466
20031,466
2003.16666666666671,468
2003.33333333333331,470
2003.41666666666671,469
2003.58333333333331,467
2003.751,466
2003.91666666666671,466
20041,466
2004.16666666666671,469
2004.33333333333331,469
2004.41666666666671,469
2004.58333333333331,467
2004.751,465
2004.83333333333331,465
20051,466
2005.16666666666671,467
2005.251,467
2005.41666666666671,469
2005.58333333333331,467
2005.66666666666671,466
2005.83333333333331,466
20061,471
2006.08333333333331,472
2006.251,474
2006.41666666666671,473
2006.51,473
2006.66666666666671,471
2006.83333333333331,470
2006.91666666666671,471
2007.08333333333331,471
2007.251,473
2007.33333333333331,473
2007.51,471
2007.66666666666671,469
2007.751,469
2007.91666666666671,469
2008.08333333333331,469
2008.251,472
2008.33333333333331,472
2008.51,471
2008.66666666666671,470
2008.751,469
2008.91666666666671,469
2009.08333333333331,469
2009.16666666666671,470
2009.33333333333331,471
2009.51,469
2009.58333333333331,468
2009.751,467
2009.91666666666671,467
20101,467
2010.16666666666671,468
2010.33333333333331,469
2010.41666666666671,468
2010.58333333333331,466
2010.751,464
2010.83333333333331,464
20111,467
2011.16666666666671,469
2011.251,471
2011.41666666666671,472
2011.58333333333331,470
2011.66666666666671,470
2011.83333333333331,469
20121,469
2012.16666666666671,470
2012.251,471
2012.41666666666671,470
2012.58333333333331,469
2012.66666666666671,468
2012.83333333333331,467
20131,468
2013.08333333333331,468
2013.251,470
2013.41666666666671,468
2013.51,467
2013.66666666666671,465
2013.83333333333331,465
2013.91666666666671,465
2014.08333333333331,465
2014.251,466
2014.33333333333331,466
2014.51,463
2014.66666666666671,463
2014.751,462
2014.91666666666671,464
2015.08333333333331,466
2015.16666666666671,466
2015.33333333333331,465
2015.51,463
2015.58333333333331,463
2015.751,462
2015.91666666666671,463
20161,464
2016.16666666666671,469
2016.33333333333331,469
2016.51,468
2016.58333333333331,467
2016.751,465
2016.91666666666671,466
20171,466
2017.16666666666671,472
2017.33333333333331,474
2017.41666666666671,473
2017.58333333333331,472
2017.751,471
2017.83333333333331,471
20181,471
2018.16666666666671,472
2018.251,473
2018.41666666666671,472
2018.58333333333331,471
2018.66666666666671,470
2018.83333333333331,470
20191,470
2019.08333333333331,471
2019.251,474
2019.41666666666671,473
2019.51,472
2019.66666666666671,471
2019.83333333333331,471
2019.91666666666671,471
2020.08333333333331,472
2020.251,472
2020.33333333333331,471
2020.51,470
2020.66666666666671,468
2020.83333333333331,467
2020.91666666666671,467
2021.08333333333331,467
2021.251,468
2021.33333333333331,467
2021.51,465
2021.66666666666671,463
2021.751,463
2021.91666666666671,463
2022.08333333333331,464
2022.16666666666671,465
2022.33333333333331,466
2022.51,463
2022.58333333333331,463
2022.751,462
2022.91666666666671,462
20231,464
2023.16666666666671,465
2023.33333333333331,470
2023.41666666666671,469
2023.58333333333331,467
2023.751,466
2023.83333333333331,466
20241,466
2024.16666666666671,468
2024.251,469
2024.41666666666671,468
2024.58333333333331,466
2024.751,464
2024.83333333333331,464
20251,468
2025.16666666666671,470
2025.251,473
2025.41666666666671,472
2025.58333333333331,471
2025.66666666666671,470
2025.83333333333331,470
20261,471
2026.08333333333331,471
2026.251,471
2026.41666666666671,470
2026.51,470
2026.66666666666671,468

Rate and persistence

-2.00 Mm³
Mean drawdown per month over 12 months
3 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

Gerber Reservoir
Gauge location
Gerber ReservoirGerber Reservoir — 38.92 Mm³Gerber Reservoir — 38.92 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 Bureau of Reclamation — Reservoir operations and Colorado River data · US Government work — public domain
How the values came to existMeasured
Period held1986–2026
Completeness81.7% 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.
Continuity82% of the months between 1986 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), Gerber Reservoir reservoir records, accessed 2026-10-05, hydrionis.com/reservoirs/reservoir-usbr-7306/

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 Gerber Reservoir 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

402 monthly observations 1986–2026 Mm³
Spatially aggregatedHigh confidenceSeptember 2026

Source: USBR — Reservoir operations and Colorado River data, RISE catalogue item 134034. Licence: Open.

Method: Monthly mean of the daily values published by the Bureau of Reclamation in acre-feet, converted to Mm³. Months with fewer than 20 days of record are not published rather than averaged from a partial month.

Stored as a volume and not as a share of capacity: the operator publishes what is in the reservoir but not what it holds when full, so a percentage cannot be computed without inventing the denominator.

Retrieved 1 October 2026.

Monthly mean of the daily values published by the Bureau of Reclamation in acre-feet, converted to Mm³. Months with fewer than 20 days of record are not published rather than averaged from a partial month.

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