Jackson Lake And Jackson Lake — storage

Storage now, against this reservoir's own record

134.56 Mm³

Stored, September 2026

10th

Percentile among 117 Seps on record

-80.0%

Against the Sep 1991–2020 average

-81.6%

Change over the 12 months to 2026-09

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

Storage, 1909–2026

Monthly mean storage

1,404 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 1,404 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,404 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
February 1919	363
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
June 1926	788
November 1926	46.1
May 1927	374
November 1927	682
May 1928	819
November 1928	765
May 1929	793
November 1929	521
May 1930	799
October 1930	332
April 1931	493
October 1931	16.8
April 1932	202
October 1932	476
April 1933	641
October 1933	259
April 1934	424
September 1934	25.0
March 1935	184
September 1935	194
March 1936	314
September 1936	512
March 1937	575
September 1937	340
February 1938	418
August 1938	750
February 1939	642
August 1939	640
February 1940	497
August 1940	407
February 1941	336
August 1941	439
January 1942	431
July 1942	991
January 1943	518
July 1943	1,052
January 1944	821
July 1944	983
January 1945	458
July 1945	1,044
December 1945	781
June 1946	1,049
December 1946	597
June 1947	1,051
December 1947	661
June 1948	1,039
December 1948	380
May 1949	682
November 1949	392
May 1950	565
November 1950	773
May 1951	657
November 1951	799
May 1952	682
November 1952	383
April 1953	565
October 1953	299
April 1954	518
October 1954	406
April 1955	603
October 1955	255
April 1956	319
October 1956	475
March 1957	168
September 1957	781
March 1958	652
September 1958	691
March 1959	595
September 1959	718
March 1960	589
September 1960	611
February 1961	365
August 1961	68.3
February 1962	157
August 1962	845
February 1963	704
August 1963	876
February 1964	781
July 1964	1,034
January 1965	757
July 1965	1,039
January 1966	866
July 1966	996
January 1967	607
July 1967	1,030
January 1968	734
June 1968	971
December 1968	763
June 1969	1,027
December 1969	743
June 1970	930
December 1970	706
June 1971	743
December 1971	756
May 1972	551
November 1972	737
May 1973	867
November 1973	761
May 1974	553
November 1974	731
May 1975	663
October 1975	719
April 1976	727
October 1976	699
April 1977	775
October 1977	290
April 1978	404
October 1978	663
April 1979	631
September 1979	619
March 1980	683
September 1980	628
March 1981	687
September 1981	623
March 1982	610
September 1982	673
March 1983	618
August 1983	726
February 1984	605
August 1984	712
February 1985	338
August 1985	288
February 1986	191
August 1986	313
February 1987	105
July 1987	291
January 1988	110
July 1988	307
January 1989	119
July 1989	1,034
January 1990	698
July 1990	1,029
December 1990	670
June 1991	1,026
December 1991	799
June 1992	941
December 1992	162
June 1993	858
December 1993	764
June 1994	1,040
November 1994	447
May 1995	657
November 1995	799
May 1996	703
November 1996	795
May 1997	646
November 1997	795
May 1998	890
October 1998	706
April 1999	688
October 1999	780
April 2000	831
October 2000	794
April 2001	799
October 2001	145
March 2002	197
September 2002	372
March 2003	352
September 2003	276
March 2004	219
September 2004	153
March 2005	184
September 2005	469
February 2006	503
August 2006	937
February 2007	783
August 2007	753
February 2008	405
August 2008	950
February 2009	795
August 2009	953
January 2010	776
July 2010	1,005
January 2011	815
July 2011	1,027
January 2012	782
July 2012	998
January 2013	758
July 2013	783
December 2013	217
June 2014	946
December 2014	801
June 2015	1,022
December 2015	681
June 2016	988
December 2016	646
May 2017	688
November 2017	797
May 2018	852
November 2018	802
May 2019	825
November 2019	715
May 2020	853
November 2020	797
April 2021	805
October 2021	162
April 2022	232
October 2022	174
April 2023	258
October 2023	687
April 2024	795
October 2024	797
March 2025	796
September 2025	732
March 2026	769
September 2026	135

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	430
Sep	674	135
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

1,404 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 1,404 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,404 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
1919.0833333333333	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
1926.4166666666667	2,061
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
1930.3333333333333	2,061
1930.75	2,056
1931.25	2,057
1931.75	2,052
1932.25	2,054
1932.75	2,057
1933.25	2,059
1933.75	2,055
1934.25	2,057
1934.6666666666667	2,052
1935.1666666666667	2,054
1935.6666666666667	2,054
1936.1666666666667	2,055
1936.6666666666667	2,058
1937.1666666666667	2,058
1937.6666666666667	2,056
1938.0833333333333	2,057
1938.5833333333333	2,060
1939.0833333333333	2,059
1939.5833333333333	2,059
1940.0833333333333	2,058
1940.5833333333333	2,056
1941.0833333333333	2,056
1941.5833333333333	2,057
1942	2,057
1942.5	2,063
1943	2,058
1943.5	2,063
1944	2,061
1944.5	2,063
1945	2,057
1945.5	2,063
1945.9166666666667	2,061
1946.4166666666667	2,063
1946.9166666666667	2,059
1947.4166666666667	2,063
1947.9166666666667	2,059
1948.4166666666667	2,063
1948.9166666666667	2,056
1949.3333333333333	2,060
1949.8333333333333	2,056
1950.3333333333333	2,058
1950.8333333333333	2,060
1951.3333333333333	2,059
1951.8333333333333	2,061
1952.3333333333333	2,060
1952.8333333333333	2,056
1953.25	2,058
1953.75	2,055
1954.25	2,058
1954.75	2,057
1955.25	2,059
1955.75	2,055
1956.25	2,055
1956.75	2,057
1957.1666666666667	2,054
1957.6666666666667	2,061
1958.1666666666667	2,059
1958.6666666666667	2,060
1959.1666666666667	2,059
1959.6666666666667	2,060
1960.1666666666667	2,059
1960.6666666666667	2,059
1961.0833333333333	2,056
1961.5833333333333	2,052
1962.0833333333333	2,053
1962.5833333333333	2,061
1963.0833333333333	2,060
1963.5833333333333	2,062
1964.0833333333333	2,061
1964.5	2,063
1965	2,060
1965.5	2,063
1966	2,061
1966.5	2,063
1967	2,059
1967.5	2,063
1968	2,060
1968.4166666666667	2,062
1968.9166666666667	2,060
1969.4166666666667	2,063
1969.9166666666667	2,060
1970.4166666666667	2,062
1970.9166666666667	2,060
1971.4166666666667	2,060
1971.9166666666667	2,060
1972.3333333333333	2,058
1972.8333333333333	2,060
1973.3333333333333	2,061
1973.8333333333333	2,060
1974.3333333333333	2,058
1974.8333333333333	2,060
1975.3333333333333	2,059
1975.75	2,060
1976.25	2,060
1976.75	2,060
1977.25	2,060
1977.75	2,055
1978.25	2,056
1978.75	2,059
1979.25	2,059
1979.6666666666667	2,059
1980.1666666666667	2,060
1980.6666666666667	2,059
1981.1666666666667	2,060
1981.6666666666667	2,059
1982.1666666666667	2,059
1982.6666666666667	2,059
1983.1666666666667	2,059
1983.5833333333333	2,060
1984.0833333333333	2,059
1984.5833333333333	2,060
1985.0833333333333	2,056
1985.5833333333333	2,055
1986.0833333333333	2,054
1986.5833333333333	2,055
1987.0833333333333	2,053
1987.5	2,055
1988	2,053
1988.5	2,055
1989	2,053
1989.5	2,063
1990	2,060
1990.5	2,063
1990.9166666666667	2,059
1991.4166666666667	2,063
1991.9166666666667	2,061
1992.4166666666667	2,062
1992.9166666666667	2,054
1993.4166666666667	2,061
1993.9166666666667	2,060
1994.4166666666667	2,063
1994.8333333333333	2,057
1995.3333333333333	2,059
1995.8333333333333	2,061
1996.3333333333333	2,060
1996.8333333333333	2,061
1997.3333333333333	2,059
1997.8333333333333	2,061
1998.3333333333333	2,062
1998.75	2,060
1999.25	2,060
1999.75	2,061
2000.25	2,061
2000.75	2,061
2001.25	2,061
2001.75	2,053
2002.1666666666667	2,054
2002.6666666666667	2,056
2003.1666666666667	2,056
2003.6666666666667	2,055
2004.1666666666667	2,054
2004.6666666666667	2,053
2005.1666666666667	2,054
2005.6666666666667	2,057
2006.0833333333333	2,058
2006.5833333333333	2,062
2007.0833333333333	2,061
2007.5833333333333	2,060
2008.0833333333333	2,056
2008.5833333333333	2,062
2009.0833333333333	2,061
2009.5833333333333	2,062
2010	2,061
2010.5	2,063
2011	2,061
2011.5	2,063
2012	2,061
2012.5	2,063
2013	2,060
2013.5	2,061
2013.9166666666667	2,054
2014.4166666666667	2,062
2014.9166666666667	2,061
2015.4166666666667	2,063
2015.9166666666667	2,060
2016.4166666666667	2,063
2016.9166666666667	2,059
2017.3333333333333	2,060
2017.8333333333333	2,061
2018.3333333333333	2,061
2018.8333333333333	2,061
2019.3333333333333	2,061
2019.8333333333333	2,060
2020.3333333333333	2,061
2020.8333333333333	2,061
2021.25	2,061
2021.75	2,054
2022.25	2,054
2022.75	2,054
2023.25	2,055
2023.75	2,060
2024.25	2,061
2024.75	2,061
2025.1666666666667	2,061
2025.6666666666667	2,060
2026.1666666666667	2,060
2026.6666666666667	2,053

Rate and persistence

-49.78 Mm³

Mean drawdown per month over 12 months

2 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	99.2% 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	2026-10-01
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 2026-10-05, 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

1,404 monthly observations 1909–2026 Mm³

Spatially aggregatedHigh confidenceSeptember 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 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.

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	430
Sep	674	135
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	430
Sep	674	135
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	430
Sep	674	135
Oct	606	677
Nov	612	686
Dec	622	702