Lake Havasu — storage

Storage now, against this reservoir's own record

659.04 Mm³

Stored, August 2026

5th

Percentile among 88 Augs on record

-8.0%

Against the Aug 1991–2020 average

-7.9%

Change over the 12 months to 2026-08

Storage in August 2026 was lower than almost every other Aug on record, ranked against 88 other Augs held for this reservoir.

Storage, 1938–2026

Monthly mean storage

1,036 monthly values, 1938 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 1,036 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,036 would be longer than this page and unusable with a screen reader.
Period	Lake Havasu (Mm³)
October 1938	91.5
February 1939	589
July 1939	592
November 1939	648
March 1940	617
August 1940	591
December 1940	531
April 1941	492
September 1941	545
January 1942	502
May 1942	421
October 1942	592
February 1943	735
June 1943	800
November 1943	763
March 1944	754
July 1944	839
December 1944	718
April 1945	784
August 1945	799
January 1946	722
May 1946	830
September 1946	797
February 1947	768
June 1947	830
October 1947	774
March 1948	726
July 1948	831
November 1948	763
April 1949	773
August 1949	806
December 1949	802
May 1950	836
September 1950	777
January 1951	761
June 1951	805
October 1951	747
February 1952	734
August 1952	769
June 1953	832
November 1953	766
June 1954	837
November 1954	762
May 1955	839
December 1955	748
April 1956	795
August 1956	789
February 1957	749
July 1957	820
December 1957	727
May 1958	816
October 1958	688
February 1959	672
July 1959	724
November 1959	688
March 1960	670
August 1960	706
December 1960	687
April 1961	713
September 1961	676
January 1962	668
May 1962	739
September 1962	687
February 1963	660
June 1963	734
October 1963	681
March 1964	662
July 1964	713
November 1964	671
April 1965	673
August 1965	685
December 1965	683
May 1966	738
September 1966	692
January 1967	664
June 1967	741
October 1967	675
February 1968	662
July 1968	731
November 1968	670
March 1969	677
August 1969	704
December 1969	672
April 1970	687
September 1970	697
January 1971	665
May 1971	748
October 1971	689
February 1972	668
June 1972	743
November 1972	672
March 1973	683
July 1973	739
December 1973	678
April 1974	714
August 1974	710
January 1975	671
May 1975	743
September 1975	701
February 1976	678
June 1976	747
October 1976	694
March 1977	685
July 1977	735
November 1977	684
April 1978	711
August 1978	702
December 1978	679
May 1979	696
September 1979	685
January 1980	683
June 1980	718
October 1980	680
February 1981	676
July 1981	738
November 1981	682
March 1982	682
August 1982	719
December 1982	691
April 1983	679
September 1983	668
January 1984	675
May 1984	704
October 1984	682
February 1985	675
June 1985	728
November 1985	692
March 1986	712
July 1986	694
December 1986	702
April 1987	703
August 1987	712
January 1988	680
May 1988	747
September 1988	692
February 1989	673
June 1989	751
October 1989	685
March 1990	675
July 1990	728
November 1990	677
April 1991	722
August 1991	716
December 1991	683
May 1992	748
September 1992	703
January 1993	692
June 1993	744
October 1993	696
February 1994	677
July 1994	729
November 1994	677
March 1995	699
August 1995	712
December 1995	680
April 1996	685
September 1996	737
January 1997	690
May 1997	734
October 1997	700
February 1998	694
June 1998	725
November 1998	671
March 1999	652
July 1999	738
December 1999	687
April 2000	672
August 2000	714
January 2001	709
May 2001	717
September 2001	694
February 2002	685
June 2002	726
October 2002	721
March 2003	687
July 2003	733
November 2003	699
April 2004	691
August 2004	715
December 2004	711
April 2005	695
September 2005	689
January 2006	700
May 2006	700
October 2006	694
February 2007	679
June 2007	726
November 2007	702
March 2008	681
July 2008	712
December 2008	703
April 2009	706
August 2009	702
January 2010	714
May 2010	732
September 2010	703
February 2011	710
June 2011	724
October 2011	707
March 2012	696
July 2012	730
November 2012	709
April 2013	702
August 2013	725
December 2013	671
May 2014	717
September 2014	719
January 2015	691
June 2015	736
October 2015	719
February 2016	682
July 2016	732
November 2016	679
March 2017	720
August 2017	722
December 2017	680
April 2018	694
September 2018	711
January 2019	699
May 2019	721
October 2019	721
February 2020	696
June 2020	717
November 2020	707
March 2021	700
July 2021	719
December 2021	692
April 2022	703
August 2022	729
January 2023	709
May 2023	710
September 2023	712
February 2024	704
June 2024	722
October 2024	696
March 2025	704
July 2025	722
November 2025	663
April 2026	653
August 2026	659

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	689	638
Feb	692	632
Mar	698	637
Apr	705	653
May	726	666
Jun	728	664
Jul	721	665
Aug	716	659
Sep	713	721
Oct	704	646
Nov	699	663
Dec	693	638

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

999 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 999 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 999 would be longer than this page and unusable with a screen reader.
Period	Lake Havasu (m)
1938.9166666666667	135
1939.25	135
1939.5833333333333	135
1940	136
1940.3333333333333	135
1940.6666666666667	135
1942.1666666666667	135
1943	136
1944	137
1944.75	137
1945.0833333333333	137
1945.9166666666667	137
1946.6666666666667	137
1947	136
1947.3333333333333	137
1947.75	136
1948.0833333333333	136
1948.4166666666667	137
1948.75	136
1949.0833333333333	135
1949.5	137
1949.8333333333333	136
1950.1666666666667	137
1950.5	137
1951	137
1951.5833333333333	137
1952	136
1952.3333333333333	137
1952.6666666666667	136
1953.3333333333333	137
1953.6666666666667	136
1954	136
1954.5	137
1954.9166666666667	136
1955.25	137
1955.5833333333333	137
1955.9166666666667	137
1956.3333333333333	137
1956.6666666666667	137
1957	136
1957.3333333333333	137
1957.6666666666667	136
1958	136
1958.4166666666667	137
1958.75	136
1959.0833333333333	136
1959.4166666666667	137
1959.75	136
1960.0833333333333	136
1960.5	137
1960.8333333333333	136
1961.1666666666667	136
1961.5	137
1961.8333333333333	136
1962.1666666666667	136
1962.5833333333333	136
1962.9166666666667	136
1963.25	136
1963.5833333333333	136
1963.9166666666667	136
1964.3333333333333	137
1964.6666666666667	136
1965	136
1965.3333333333333	137
1965.6666666666667	136
1966	136
1966.4166666666667	137
1966.75	136
1967.0833333333333	136
1967.4166666666667	137
1967.75	136
1968.0833333333333	136
1968.5	137
1968.8333333333333	136
1969.1666666666667	136
1969.5	137
1969.8333333333333	136
1970.25	136
1970.5833333333333	137
1970.9166666666667	136
1971.25	137
1971.5833333333333	137
1971.9166666666667	136
1972.3333333333333	137
1972.6666666666667	136
1973	136
1973.3333333333333	137
1973.6666666666667	136
1974	136
1974.4166666666667	137
1974.75	136
1975.0833333333333	136
1975.4166666666667	137
1975.75	136
1976.1666666666667	136
1976.5	137
1976.8333333333333	136
1977.1666666666667	136
1977.5	137
1977.8333333333333	136
1978.25	136
1978.5833333333333	136
1978.9166666666667	136
1979.25	136
1979.5833333333333	136
1979.9166666666667	136
1980.3333333333333	137
1980.6666666666667	136
1981	136
1981.3333333333333	137
1981.6666666666667	136
1982.0833333333333	136
1982.4166666666667	137
1982.75	136
1983.0833333333333	136
1983.4166666666667	137
1983.75	136
1984.1666666666667	136
1984.5	136
1984.8333333333333	136
1985.1666666666667	136
1985.5	136
1985.8333333333333	136
1986.25	136
1986.5833333333333	137
1986.9166666666667	136
1987.25	136
1987.5833333333333	137
1987.9166666666667	136
1988.3333333333333	137
1988.6666666666667	136
1989	136
1989.3333333333333	137
1989.6666666666667	136
1990.0833333333333	136
1990.4166666666667	137
1990.75	136
1991.0833333333333	136
1991.4166666666667	137
1991.75	136
1992.1666666666667	136
1992.5	137
1992.8333333333333	136
1993.1666666666667	136
1993.5	137
1993.8333333333333	136
1994.25	136
1994.5833333333333	136
1994.9166666666667	136
1995.25	136
1995.5833333333333	137
1996	136
1996.3333333333333	137
1996.6666666666667	137
1997	136
1997.3333333333333	137
1997.6666666666667	137
1998.0833333333333	136
1998.4166666666667	137
1998.75	136
1999.0833333333333	136
1999.4166666666667	137
1999.75	136
2000.1666666666667	136
2000.5	137
2000.8333333333333	136
2001.1666666666667	137
2001.5	137
2001.9166666666667	136
2002.25	137
2002.5833333333333	136
2002.9166666666667	136
2003.25	136
2003.5833333333333	137
2004	135
2004.3333333333333	136
2004.6666666666667	137
2005	137
2005.3333333333333	137
2005.6666666666667	136
2006.0833333333333	136
2006.4166666666667	136
2006.75	136
2007.0833333333333	136
2007.4166666666667	137
2007.8333333333333	136
2008.1666666666667	136
2008.5	137
2008.8333333333333	136
2009.1666666666667	136
2009.5	137
2009.9166666666667	136
2010.25	136
2010.5833333333333	137
2010.9166666666667	136
2011.25	137
2011.5833333333333	137
2012	136
2012.3333333333333	137
2012.6666666666667	137
2013	136
2013.3333333333333	137
2013.6666666666667	137
2014.0833333333333	136
2014.4166666666667	137
2014.75	137
2015.0833333333333	136
2015.4166666666667	137
2015.8333333333333	136
2016.1666666666667	136
2016.5	137
2016.8333333333333	136
2017.1666666666667	137
2017.5	137
2017.9166666666667	136
2018.25	136
2018.5833333333333	136
2018.9166666666667	137
2019.25	136
2019.5833333333333	136
2020	136
2020.3333333333333	136
2020.6666666666667	136
2021	136
2021.3333333333333	137
2021.75	137
2022.0833333333333	136
2022.4166666666667	137
2022.75	137
2023.0833333333333	136
2023.4166666666667	136
2023.8333333333333	136
2024.1666666666667	136
2024.5	137
2024.8333333333333	136
2025.1666666666667	136
2025.5	137
2025.9166666666667	136
2026.25	137
2026.5833333333333	137

Rate and persistence

-4.72 Mm³

Mean drawdown per month over 12 months

11 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 Havasu

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	1938–2026
Completeness	97.0% 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.
Continuity	97% of the months between 1938 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-3515.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), Lake Havasu reservoir records, accessed 2026-09-02, hydrionis.com/reservoirs/reservoir-usbr-3515/

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 Havasu 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

1,036 monthly observations 1938–2026 Mm³

Spatially aggregatedHigh confidenceAugust 2026

Source: USBR — Reservoir operations and Colorado River data, RISE catalogue item 6129. 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	689	638
Feb	692	632
Mar	698	637
Apr	705	653
May	726	666
Jun	728	664
Jul	721	665
Aug	716	659
Sep	713	721
Oct	704	646
Nov	699	663
Dec	693	638

Period	1991–2020 average (Mm³)	Most recent 12 months (Mm³)
Jan	689	638
Feb	692	632
Mar	698	637
Apr	705	653
May	726	666
Jun	728	664
Jul	721	665
Aug	716	659
Sep	713	721
Oct	704	646
Nov	699	663
Dec	693	638

Period	1991–2020 average (Mm³)	Most recent 12 months (Mm³)
Jan	689	638
Feb	692	632
Mar	698	637
Apr	705	653
May	726	666
Jun	728	664
Jul	721	665
Aug	716	659
Sep	713	721
Oct	704	646
Nov	699	663
Dec	693	638