Banks Lake — storage

Storage now, against this reservoir's own record

844.10 Mm³

Stored, April 2026

88th

Percentile among 70 Aprs on record

+2.5%

Against the Apr 1991–2020 average

+2.0%

Change over the 12 months to 2026-04

Storage in April 2026 was higher than most Aprs on record, ranked against 70 other Aprs held for this reservoir.

Storage, 1952–2026

Monthly mean storage

786 monthly values, 1952 to 2026

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 786 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 786 would be longer than this page and unusable with a screen reader.
Period	Banks Lake (Mm³)
August 1952	102
July 1953	316
August 1954	523
November 1954	452
February 1955	559
May 1955	315
September 1955	674
December 1955	851
April 1956	852
November 1956	633
February 1957	599
May 1957	613
August 1957	816
December 1957	486
March 1958	859
June 1958	835
May 1959	623
August 1959	713
November 1959	613
February 1960	622
June 1960	706
September 1960	672
December 1960	488
April 1961	594
July 1961	673
October 1961	562
January 1962	537
May 1962	505
August 1962	714
November 1962	316
March 1963	320
June 1963	78.8
September 1963	591
December 1963	381
April 1964	226
July 1964	682
October 1964	537
February 1965	495
May 1965	298
August 1965	789
November 1965	563
March 1966	561
June 1966	750
September 1966	826
March 1967	862
June 1967	643
September 1967	629
January 1968	878
July 1968	685
October 1968	758
May 1969	542
September 1969	821
December 1969	734
March 1970	782
June 1970	863
October 1970	761
January 1971	872
April 1971	759
August 1971	873
November 1971	734
March 1972	870
June 1972	579
October 1972	801
January 1973	755
April 1973	560
July 1973	257
November 1973	859
May 1974	459
August 1974	746
December 1974	874
March 1975	869
June 1975	659
September 1975	870
January 1976	880
April 1976	833
July 1976	867
November 1976	877
February 1977	872
May 1977	655
August 1977	841
December 1977	877
May 1978	603
August 1978	785
December 1978	855
March 1979	842
June 1979	718
September 1979	835
June 1980	857
September 1980	406
April 1981	831
August 1981	871
April 1982	818
July 1982	815
October 1982	835
July 1983	848
October 1983	674
June 1984	836
October 1984	832
June 1985	832
September 1985	763
December 1985	480
April 1986	745
July 1986	834
October 1986	813
February 1987	810
May 1987	875
August 1987	867
November 1987	815
March 1988	808
June 1988	835
September 1988	862
January 1989	826
April 1989	734
July 1989	811
October 1989	845
February 1990	827
May 1990	833
August 1990	835
December 1990	819
March 1991	799
June 1991	830
September 1991	831
January 1992	827
April 1992	825
July 1992	833
November 1992	836
February 1993	837
May 1993	846
August 1993	830
December 1993	822
October 1994	241
January 1995	176
May 1995	825
August 1995	826
November 1995	832
February 1996	833
June 1996	823
September 1996	825
March 1998	838
July 1998	823
October 1998	765
January 1999	835
April 1999	849
August 1999	844
November 1999	827
February 2000	833
June 2000	821
September 2000	807
December 2000	850
March 2001	866
July 2001	817
October 2001	774
January 2002	845
August 2002	787
November 2002	782
February 2003	851
May 2003	817
September 2003	764
December 2003	817
March 2004	829
July 2004	835
October 2004	768
January 2005	833
April 2005	816
August 2005	770
November 2005	798
February 2006	829
June 2006	819
September 2006	796
December 2006	833
March 2007	845
July 2007	846
October 2007	796
January 2008	839
May 2008	824
August 2008	786
November 2008	836
February 2009	843
June 2009	827
September 2009	738
December 2009	812
March 2010	833
July 2010	817
October 2010	758
January 2011	801
May 2011	807
August 2011	602
January 2012	381
April 2012	812
August 2012	823
November 2012	772
February 2013	833
June 2013	863
September 2013	782
December 2013	746
March 2014	831
July 2014	849
October 2014	760
January 2015	835
May 2015	838
August 2015	817
November 2015	790
February 2016	835
June 2016	798
September 2016	780
December 2016	831
April 2017	849
July 2017	831
October 2017	830
January 2018	818
May 2018	841
August 2018	787
November 2018	831
March 2019	825
June 2019	840
September 2019	804
December 2019	815
April 2020	839
July 2020	831
October 2020	825
February 2021	816
May 2021	838
August 2021	787
November 2021	827
March 2022	836
June 2022	828
September 2022	781
January 2023	826
April 2023	837
July 2023	845
October 2023	817
February 2024	832
May 2024	824
August 2024	756
December 2024	828
March 2025	846
June 2025	837
September 2025	796
January 2026	831
April 2026	844

The reservoir's year

Seasonal storage profile

Each calendar month's reference average, against the most recent year

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
Period	1991–2020 average (Mm³)	Most recent 12 months (Mm³)
Jan	789	831
Feb	807	831
Mar	829	852
Apr	823	844
May	825	810
Jun	831	837
Jul	834	853
Aug	782	791
Sep	753	796
Oct	782	828
Nov	780	838
Dec	774	835

Why this page shows a volume and not a percentage

Percentage full is a division, and the denominator is missing

“Percentage full” is the figure a drought is discussed in, and it is stored volume divided by capacity. Capacity is published on several different bases — gross, usable, live, and the figure at a particular spillway or licence condition — and dividing a stored volume by the wrong one produces a percentage confidently wrong by the ratio between them, at exactly the moment the number matters most.

Hydrionis holds storage measurements for this reservoir and does not hold a compatible authoritative capacity figure for it, so percentage full is not calculated. The volume above is what was actually measured. Where you need a percentage, take the publisher’s own capacity on its own stated basis and divide it yourself — the source is linked below, and knowing which basis you used is the whole point.

Water level

Monthly mean water surface elevation

841 monthly values

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 841 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 841 would be longer than this page and unusable with a screen reader.
Period	Banks Lake (m)
1951.75	468
1952.0833333333333	468
1952.3333333333333	468
1952.6666666666667	470
1952.9166666666667	468
1953.25	467
1953.5	473
1953.8333333333333	468
1954.0833333333333	468
1954.4166666666667	470
1954.6666666666667	475
1955	476
1955.25	474
1955.5833333333333	477
1955.8333333333333	477
1956.1666666666667	478
1956.4166666666667	479
1956.75	476
1957	476
1957.3333333333333	476
1957.5833333333333	478
1957.9166666666667	475
1958.1666666666667	478
1958.5	479
1958.75	478
1959.0833333333333	479
1959.3333333333333	476
1959.6666666666667	477
1959.9166666666667	476
1960.25	475
1960.5	477
1960.8333333333333	475
1961.0833333333333	475
1961.4166666666667	475
1961.6666666666667	477
1962	475
1962.3333333333333	475
1962.5833333333333	477
1962.9166666666667	473
1963.1666666666667	473
1963.5	472
1963.75	474
1964.0833333333333	474
1964.3333333333333	472
1964.6666666666667	477
1964.9166666666667	475
1965.25	474
1965.5	476
1965.8333333333333	476
1966.0833333333333	476
1966.4166666666667	477
1966.6666666666667	478
1967	479
1967.25	477
1967.5833333333333	478
1967.8333333333333	479
1968.1666666666667	478
1968.4166666666667	475
1968.75	477
1969	479
1969.3333333333333	475
1969.5833333333333	477
1969.9166666666667	477
1970.1666666666667	478
1970.5	478
1970.75	477
1971.0833333333333	478
1971.3333333333333	476
1971.6666666666667	478
1972	478
1972.25	477
1972.5833333333333	478
1972.8333333333333	477
1973.1666666666667	477
1973.4166666666667	471
1973.75	478
1974	479
1974.3333333333333	474
1974.5833333333333	477
1974.9166666666667	478
1975.1666666666667	478
1975.5	478
1975.75	477
1976.0833333333333	479
1976.3333333333333	477
1976.6666666666667	478
1976.9166666666667	478
1977.25	476
1977.5	478
1977.8333333333333	478
1978.0833333333333	479
1978.4166666666667	476
1978.6666666666667	476
1979	478
1979.25	476
1979.5833333333333	478
1980.25	477
1980.5833333333333	477
1981.1666666666667	478
1981.5	478
1981.75	478
1982.5	478
1982.75	478
1983.5	478
1984.25	476
1984.5	478
1985.25	478
1985.5	478
1985.8333333333333	475
1986.0833333333333	475
1986.4166666666667	478
1986.6666666666667	477
1987	478
1987.25	478
1987.5833333333333	478
1987.8333333333333	478
1988.1666666666667	478
1988.4166666666667	478
1988.75	478
1989	478
1989.3333333333333	477
1989.5833333333333	478
1989.9166666666667	478
1990.1666666666667	478
1990.5	478
1990.75	478
1991.0833333333333	478
1991.3333333333333	477
1991.6666666666667	478
1991.9166666666667	478
1992.25	478
1992.5	478
1992.8333333333333	478
1993.0833333333333	478
1993.4166666666667	478
1993.6666666666667	478
1994.5833333333333	476
1994.9166666666667	471
1995.1666666666667	478
1995.5	478
1995.75	478
1996.0833333333333	478
1996.3333333333333	478
1996.6666666666667	478
1998.1666666666667	478
1998.5	478
1998.75	477
1999.0833333333333	478
1999.3333333333333	478
1999.6666666666667	478
1999.9166666666667	478
2000.25	478
2000.5	478
2000.8333333333333	478
2001.0833333333333	478
2001.4166666666667	478
2001.6666666666667	477
2002	478
2002.25	478
2002.8333333333333	478
2003.0833333333333	478
2003.4166666666667	478
2003.6666666666667	477
2004	478
2004.25	478
2004.5833333333333	477
2004.8333333333333	477
2005.1666666666667	478
2005.4166666666667	478
2005.75	478
2006	478
2006.3333333333333	478
2006.6666666666667	478
2006.9166666666667	478
2007.25	478
2007.5	478
2007.8333333333333	478
2008.0833333333333	478
2008.4166666666667	478
2008.6666666666667	478
2009	478
2009.25	478
2009.5833333333333	478
2009.8333333333333	478
2010.1666666666667	478
2010.4166666666667	478
2010.75	477
2011	478
2011.3333333333333	478
2011.5833333333333	476
2011.9166666666667	471
2012.1666666666667	478
2012.5	478
2012.75	477
2013.0833333333333	478
2013.3333333333333	478
2013.6666666666667	478
2013.9166666666667	477
2014.25	478
2014.5	478
2014.8333333333333	478
2015.0833333333333	478
2015.4166666666667	478
2015.6666666666667	477
2016	478
2016.3333333333333	477
2016.5833333333333	478
2016.9166666666667	478
2017.1666666666667	478
2017.5	478
2017.75	478
2018.0833333333333	478
2018.3333333333333	478
2018.6666666666667	478
2018.9166666666667	478
2019.25	478
2019.5	478
2019.8333333333333	478
2020.0833333333333	478
2020.4166666666667	478
2020.6666666666667	478
2021	478
2021.25	478
2021.5833333333333	478
2021.8333333333333	478
2022.1666666666667	478
2022.4166666666667	478
2022.75	478
2023	478
2023.3333333333333	478
2023.5833333333333	478
2023.9166666666667	478
2024.1666666666667	478
2024.5	478
2024.75	478
2025.0833333333333	478
2025.3333333333333	478
2025.6666666666667	478
2025.9166666666667	478
2026.25	478

Rate and persistence

+1.41 Mm³

Mean change per month over 12 months

0 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

Banks Lake

Gauge location

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 exist	Measured
Period held	1952–2026
Completeness	87.3% 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.
Continuity	87% of the months between 1952 and 2026 are held. Monthly means of the publisher's own daily record.
Last read from the publisher	2026-09-01
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

Use this data

Machine-readable JSON /api/v1/observations/by-subject/reservoir-usbr-7264.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), Banks Lake reservoir records, accessed 2026-09-02, hydrionis.com/reservoirs/reservoir-usbr-7264/

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 Banks Lake 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

786 monthly observations 1952–2026 Mm³

Spatially aggregatedHigh confidenceApril 2026

Source: USBR — Reservoir operations and Colorado River data, RISE catalogue item 129465. 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 September 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.

Period	1991–2020 average (Mm³)	Most recent 12 months (Mm³)
Jan	789	831
Feb	807	831
Mar	829	852
Apr	823	844
May	825	810
Jun	831	837
Jul	834	853
Aug	782	791
Sep	753	796
Oct	782	828
Nov	780	838
Dec	774	835

Period	1991–2020 average (Mm³)	Most recent 12 months (Mm³)
Jan	789	831
Feb	807	831
Mar	829	852
Apr	823	844
May	825	810
Jun	831	837
Jul	834	853
Aug	782	791
Sep	753	796
Oct	782	828
Nov	780	838
Dec	774	835

Period	1991–2020 average (Mm³)	Most recent 12 months (Mm³)
Jan	789	831
Feb	807	831
Mar	829	852
Apr	823	844
May	825	810
Jun	831	837
Jul	834	853
Aug	782	791
Sep	753	796
Oct	782	828
Nov	780	838
Dec	774	835