Jackson Lake And Jackson Lake — storage

Storage now, against this reservoir's own record

435.50 Mm³

Stored, August 2026

21st

Percentile among 117 Augs on record

-46.8%

Against the Aug 1991–2020 average

-49.6%

Change over the 12 months to 2026-08

Storage in August 2026 was lower than most Augs on record, ranked against 117 other Augs held for this reservoir.

Storage, 1909–2026

Monthly mean storage

1,403 monthly values, 1909 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 1,403 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,403 would be longer than this page and unusable with a screen reader.
Period	Jackson Lake And Jackson Lake (Mm³)
October 1909	142
April 1910	185
October 1910	159
April 1911	156
September 1911	93.2
March 1912	61.3
September 1912	211
March 1913	81.2
September 1913	175
March 1914	123
September 1914	114
March 1915	228
August 1915	144
February 1916	218
August 1916	701
February 1917	455
August 1917	648
February 1918	584
August 1918	551
January 1919	335
July 1919	165
January 1920	114
July 1920	814
January 1921	326
July 1921	854
January 1922	339
July 1922	870
December 1922	370
June 1923	953
December 1923	257
June 1924	574
December 1924	105
June 1925	943
December 1925	577
May 1926	881
November 1926	46.1
May 1927	374
November 1927	682
May 1928	819
November 1928	765
May 1929	793
November 1929	521
April 1930	651
October 1930	332
April 1931	493
October 1931	16.8
April 1932	202
October 1932	476
April 1933	641
September 1933	326
March 1934	382
September 1934	25.0
March 1935	184
September 1935	194
March 1936	314
September 1936	512
March 1937	575
August 1937	591
February 1938	418
August 1938	750
February 1939	642
August 1939	640
February 1940	497
August 1940	407
January 1941	308
July 1941	699
January 1942	431
July 1942	991
January 1943	518
July 1943	1,052
January 1944	821
June 1944	1,051
December 1944	428
June 1945	940
December 1945	781
June 1946	1,049
December 1946	597
June 1947	1,051
December 1947	661
May 1948	844
November 1948	339
May 1949	682
November 1949	392
May 1950	565
November 1950	773
May 1951	657
October 1951	775
April 1952	541
October 1952	360
April 1953	565
October 1953	299
April 1954	518
October 1954	406
April 1955	603
September 1955	304
March 1956	463
September 1956	523
March 1957	168
September 1957	781
March 1958	652
September 1958	691
February 1959	586
August 1959	873
February 1960	593
August 1960	827
February 1961	365
August 1961	68.3
February 1962	157
August 1962	845
January 1963	667
July 1963	1,016
January 1964	765
July 1964	1,034
January 1965	757
July 1965	1,039
January 1966	866
June 1966	1,035
December 1966	598
June 1967	877
December 1967	726
June 1968	971
December 1968	763
June 1969	1,027
December 1969	743
May 1970	745
November 1970	688
May 1971	525
November 1971	742
May 1972	551
November 1972	737
May 1973	867
October 1973	746
April 1974	737
October 1974	725
April 1975	786
October 1975	719
April 1976	727
October 1976	699
April 1977	775
September 1977	299
March 1978	408
September 1978	663
March 1979	673
September 1979	619
March 1980	683
September 1980	628
February 1981	689
August 1981	678
February 1982	639
August 1982	749
February 1983	615
August 1983	726
February 1984	605
August 1984	712
January 1985	345
July 1985	344
January 1986	181
July 1986	358
January 1987	103
July 1987	291
January 1988	110
June 1988	347
December 1988	101
June 1989	865
December 1989	699
June 1990	1,030
December 1990	670
June 1991	1,026
December 1991	799
May 1992	998
November 1992	153
May 1993	406
November 1993	765
May 1994	964
November 1994	447
May 1995	657
October 1995	794
April 1996	711
October 1996	789
April 1997	590
October 1997	800
April 1998	805
October 1998	706
March 1999	761
September 1999	867
March 2000	809
September 2000	835
March 2001	788
September 2001	239
March 2002	197
September 2002	372
February 2003	333
August 2003	569
February 2004	205
August 2004	291
February 2005	171
August 2005	564
February 2006	503
July 2006	1,026
January 2007	785
July 2007	938
January 2008	383
July 2008	1,032
January 2009	796
July 2009	1,015
January 2010	776
June 2010	1,022
December 2010	806
June 2011	630
December 2011	774
June 2012	1,036
December 2012	746
June 2013	982
November 2013	201
May 2014	523
November 2014	794
May 2015	990
November 2015	677
May 2016	896
November 2016	619
May 2017	688
October 2017	789
April 2018	789
October 2018	795
April 2019	813
October 2019	707
April 2020	796
October 2020	795
March 2021	803
September 2021	258
March 2022	218
September 2022	225
March 2023	238
September 2023	739
March 2024	769
September 2024	827
February 2025	806
August 2025	863
February 2026	749
August 2026	435

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	629	736
Feb	637	749
Mar	641	769
Apr	641	859
May	746	972
Jun	934	959
Jul	939	735
Aug	819	435
Sep	674	732
Oct	606	677
Nov	612	686
Dec	622	702

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

1,403 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 1,403 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,403 would be longer than this page and unusable with a screen reader.
Period	Jackson Lake And Jackson Lake (m)
1909.75	2,053
1910.25	2,054
1910.75	2,053
1911.25	2,053
1911.6666666666667	2,053
1912.1666666666667	2,052
1912.6666666666667	2,054
1913.1666666666667	2,052
1913.6666666666667	2,054
1914.1666666666667	2,053
1914.6666666666667	2,053
1915.1666666666667	2,054
1915.5833333333333	2,053
1916.0833333333333	2,054
1916.5833333333333	2,060
1917.0833333333333	2,057
1917.5833333333333	2,059
1918.0833333333333	2,058
1918.5833333333333	2,058
1919	2,056
1919.5	2,054
1920	2,053
1920.5	2,061
1921	2,056
1921.5	2,061
1922	2,056
1922.5	2,061
1922.9166666666667	2,056
1923.4166666666667	2,062
1923.9166666666667	2,055
1924.4166666666667	2,058
1924.9166666666667	2,053
1925.4166666666667	2,062
1925.9166666666667	2,058
1926.3333333333333	2,062
1926.8333333333333	2,052
1927.3333333333333	2,056
1927.8333333333333	2,060
1928.3333333333333	2,061
1928.8333333333333	2,060
1929.3333333333333	2,061
1929.8333333333333	2,058
1930.25	2,059
1930.75	2,056
1931.25	2,057
1931.75	2,052
1932.25	2,054
1932.75	2,057
1933.25	2,059
1933.6666666666667	2,056
1934.1666666666667	2,056
1934.6666666666667	2,052
1935.1666666666667	2,054
1935.6666666666667	2,054
1936.1666666666667	2,055
1936.6666666666667	2,058
1937.1666666666667	2,058
1937.5833333333333	2,059
1938.0833333333333	2,057
1938.5833333333333	2,060
1939.0833333333333	2,059
1939.5833333333333	2,059
1940.0833333333333	2,058
1940.5833333333333	2,056
1941	2,055
1941.5	2,060
1942	2,057
1942.5	2,063
1943	2,058
1943.5	2,063
1944	2,061
1944.4166666666667	2,063
1944.9166666666667	2,057
1945.4166666666667	2,062
1945.9166666666667	2,061
1946.4166666666667	2,063
1946.9166666666667	2,059
1947.4166666666667	2,063
1947.9166666666667	2,059
1948.3333333333333	2,061
1948.8333333333333	2,056
1949.3333333333333	2,060
1949.8333333333333	2,056
1950.3333333333333	2,058
1950.8333333333333	2,060
1951.3333333333333	2,059
1951.75	2,060
1952.25	2,058
1952.75	2,056
1953.25	2,058
1953.75	2,055
1954.25	2,058
1954.75	2,057
1955.25	2,059
1955.6666666666667	2,055
1956.1666666666667	2,057
1956.6666666666667	2,058
1957.1666666666667	2,054
1957.6666666666667	2,061
1958.1666666666667	2,059
1958.6666666666667	2,060
1959.0833333333333	2,059
1959.5833333333333	2,061
1960.0833333333333	2,059
1960.5833333333333	2,061
1961.0833333333333	2,056
1961.5833333333333	2,052
1962.0833333333333	2,053
1962.5833333333333	2,061
1963	2,059
1963.5	2,063
1964	2,060
1964.5	2,063
1965	2,060
1965.5	2,063
1966	2,061
1966.4166666666667	2,063
1966.9166666666667	2,059
1967.4166666666667	2,061
1967.9166666666667	2,060
1968.4166666666667	2,062
1968.9166666666667	2,060
1969.4166666666667	2,063
1969.9166666666667	2,060
1970.3333333333333	2,060
1970.8333333333333	2,060
1971.3333333333333	2,058
1971.8333333333333	2,060
1972.3333333333333	2,058
1972.8333333333333	2,060
1973.3333333333333	2,061
1973.75	2,060
1974.25	2,060
1974.75	2,060
1975.25	2,061
1975.75	2,060
1976.25	2,060
1976.75	2,060
1977.25	2,060
1977.6666666666667	2,055
1978.1666666666667	2,057
1978.6666666666667	2,059
1979.1666666666667	2,059
1979.6666666666667	2,059
1980.1666666666667	2,060
1980.6666666666667	2,059
1981.0833333333333	2,060
1981.5833333333333	2,059
1982.0833333333333	2,059
1982.5833333333333	2,060
1983.0833333333333	2,059
1983.5833333333333	2,060
1984.0833333333333	2,059
1984.5833333333333	2,060
1985	2,056
1985.5	2,056
1986	2,054
1986.5	2,056
1987	2,053
1987.5	2,055
1988	2,053
1988.4166666666667	2,056
1988.9166666666667	2,053
1989.4166666666667	2,061
1989.9166666666667	2,060
1990.4166666666667	2,063
1990.9166666666667	2,059
1991.4166666666667	2,063
1991.9166666666667	2,061
1992.3333333333333	2,063
1992.8333333333333	2,053
1993.3333333333333	2,056
1993.8333333333333	2,060
1994.3333333333333	2,062
1994.8333333333333	2,057
1995.3333333333333	2,059
1995.75	2,061
1996.25	2,060
1996.75	2,061
1997.25	2,059
1997.75	2,061
1998.25	2,061
1998.75	2,060
1999.1666666666667	2,060
1999.6666666666667	2,061
2000.1666666666667	2,061
2000.6666666666667	2,061
2001.1666666666667	2,061
2001.6666666666667	2,055
2002.1666666666667	2,054
2002.6666666666667	2,056
2003.0833333333333	2,056
2003.5833333333333	2,058
2004.0833333333333	2,054
2004.5833333333333	2,055
2005.0833333333333	2,054
2005.5833333333333	2,058
2006.0833333333333	2,058
2006.5	2,063
2007	2,061
2007.5	2,062
2008	2,056
2008.5	2,063
2009	2,061
2009.5	2,063
2010	2,061
2010.4166666666667	2,063
2010.9166666666667	2,061
2011.4166666666667	2,059
2011.9166666666667	2,060
2012.4166666666667	2,063
2012.9166666666667	2,060
2013.4166666666667	2,063
2013.8333333333333	2,054
2014.3333333333333	2,058
2014.8333333333333	2,061
2015.3333333333333	2,063
2015.8333333333333	2,059
2016.3333333333333	2,062
2016.8333333333333	2,059
2017.3333333333333	2,060
2017.75	2,061
2018.25	2,061
2018.75	2,061
2019.25	2,061
2019.75	2,060
2020.25	2,061
2020.75	2,061
2021.1666666666667	2,061
2021.6666666666667	2,055
2022.1666666666667	2,054
2022.6666666666667	2,054
2023.1666666666667	2,055
2023.6666666666667	2,060
2024.1666666666667	2,060
2024.6666666666667	2,061
2025.0833333333333	2,061
2025.5833333333333	2,061
2026.0833333333333	2,060
2026.5833333333333	2,057

Rate and persistence

-35.66 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

Jackson Lake And Jackson 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	1909–2026
Completeness	99.1% 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	99% of the months between 1909 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-7185.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), Jackson Lake And Jackson Lake reservoir records, accessed 2026-09-02, hydrionis.com/reservoirs/reservoir-usbr-7185/

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 Jackson Lake And Jackson 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

1,403 monthly observations 1909–2026 Mm³

Spatially aggregatedHigh confidenceAugust 2026

Source: USBR — Reservoir operations and Colorado River data, RISE catalogue item 131199. 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	629	736
Feb	637	749
Mar	641	769
Apr	641	859
May	746	972
Jun	934	959
Jul	939	735
Aug	819	435
Sep	674	732
Oct	606	677
Nov	612	686
Dec	622	702

Period	1991–2020 average (Mm³)	Most recent 12 months (Mm³)
Jan	629	736
Feb	637	749
Mar	641	769
Apr	641	859
May	746	972
Jun	934	959
Jul	939	735
Aug	819	435
Sep	674	732
Oct	606	677
Nov	612	686
Dec	622	702

Period	1991–2020 average (Mm³)	Most recent 12 months (Mm³)
Jan	629	736
Feb	637	749
Mar	641	769
Apr	641	859
May	746	972
Jun	934	959
Jul	939	735
Aug	819	435
Sep	674	732
Oct	606	677
Nov	612	686
Dec	622	702