Cle Elum Lake — storage

Storage now, against this reservoir's own record

115.94 Mm³

Stored, August 2026

33rd

Percentile among 120 Augs on record

-49.0%

Against the Aug 1991–2020 average

+105.6%

Change over the 12 months to 2026-08

Storage in August 2026 was around the middle of the Aug record, ranked against 120 other Augs held for this reservoir.

Storage, 1906–2026

Monthly mean storage

1,439 monthly values, 1906 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 1,439 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,439 would be longer than this page and unusable with a screen reader.
Period	Cle Elum Lake (Mm³)
October 1906	7.39
April 1907	9.86
October 1907	8.22
April 1908	37.4
October 1908	16.9
April 1909	33.1
October 1909	6.90
April 1910	35.2
October 1910	16.4
April 1911	33.3
October 1911	10.7
April 1912	33.3
October 1912	6.97
April 1913	23.7
October 1913	9.40
April 1914	31.4
October 1914	15.0
April 1915	34.0
October 1915	8.34
April 1916	33.1
October 1916	8.59
April 1917	33.0
October 1917	12.4
April 1918	34.4
October 1918	12.1
April 1919	34.4
October 1919	7.97
April 1920	29.6
October 1920	26.7
April 1921	33.2
November 1921	31.3
May 1922	35.1
November 1922	14.0
May 1923	36.4
November 1923	12.4
May 1924	36.2
November 1924	28.3
May 1925	36.9
November 1925	10.2
May 1926	33.1
November 1926	31.4
May 1927	35.4
November 1927	33.5
May 1928	37.0
November 1928	14.0
May 1929	35.6
November 1929	17.1
May 1930	33.7
November 1930	25.0
May 1931	35.4
November 1931	31.4
May 1932	39.8
November 1932	73.5
May 1933	56.3
November 1933	293
May 1934	363
November 1934	197
May 1935	446
November 1935	214
May 1936	461
November 1936	181
May 1937	404
November 1937	279
May 1938	507
November 1938	264
May 1939	539
November 1939	256
May 1940	540
November 1940	135
May 1941	370
November 1941	121
May 1942	380
November 1942	131
May 1943	484
November 1943	343
May 1944	536
November 1944	180
May 1945	505
November 1945	105
May 1946	432
November 1946	331
May 1947	539
November 1947	295
May 1948	478
November 1948	278
May 1949	446
November 1949	79.2
May 1950	405
November 1950	267
May 1951	494
December 1951	283
June 1952	533
December 1952	109
June 1953	542
December 1953	307
June 1954	513
December 1954	361
June 1955	532
December 1955	384
June 1956	520
December 1956	390
June 1957	525
December 1957	89.0
June 1958	532
December 1958	241
June 1959	534
December 1959	438
June 1960	534
December 1960	190
June 1961	521
December 1961	189
June 1962	546
December 1962	279
June 1963	531
December 1963	124
June 1964	450
December 1964	347
June 1965	538
December 1965	199
June 1966	511
December 1966	198
June 1967	521
December 1967	310
June 1968	529
December 1968	248
June 1969	534
December 1969	162
June 1970	511
December 1970	148
June 1971	498
December 1971	340
June 1972	492
December 1972	362
June 1973	379
December 1973	89.9
June 1974	480
December 1974	350
June 1975	489
December 1975	426
June 1976	509
December 1976	407
June 1977	448
December 1977	241
June 1978	530
December 1978	57.6
June 1979	476
December 1979	457
June 1980	537
December 1980	113
June 1981	522
January 1982	55.3
July 1982	501
January 1983	323
July 1983	489
January 1984	316
July 1984	505
January 1985	216
July 1985	353
January 1986	149
July 1986	344
January 1987	129
July 1987	254
January 1988	38.4
July 1988	365
January 1989	242
July 1989	389
January 1990	222
July 1990	478
January 1991	411
July 1991	500
January 1992	287
July 1992	220
January 1993	75.0
July 1993	262
January 1994	33.2
July 1994	224
January 1995	116
July 1995	471
January 1996	402
July 1996	479
January 1997	248
July 1997	526
January 1998	394
July 1998	462
January 1999	217
July 1999	535
January 2000	393
July 2000	453
January 2001	115
July 2001	207
January 2002	174
July 2002	509
January 2003	196
July 2003	406
January 2004	185
July 2004	384
January 2005	255
July 2005	251
January 2006	109
July 2006	472
January 2007	293
July 2007	420
January 2008	163
July 2008	495
January 2009	365
July 2009	430
January 2010	190
July 2010	485
January 2011	319
July 2011	538
February 2012	388
August 2012	360
February 2013	342
August 2013	213
February 2014	234
August 2014	235
February 2015	459
August 2015	99.5
February 2016	326
August 2016	188
February 2017	208
August 2017	241
February 2018	325
August 2018	189
February 2019	200
August 2019	97.4
February 2020	240
August 2020	225
February 2021	252
August 2021	218
February 2022	349
August 2022	301
February 2023	220
August 2023	112
February 2024	156
August 2024	88.4
February 2025	70.0
August 2025	56.4
February 2026	410
August 2026	116

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	244	366
Feb	279	410
Mar	308	459
Apr	354	531
May	434	535
Jun	492	476
Jul	412	310
Aug	227	116
Sep	129	22.2
Oct	132	19.7
Nov	170	70.1
Dec	210	242

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.

Rate and persistence

+4.96 Mm³

Mean change 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

Cle Elum 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	1906–2026
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 1906 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-7170.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), Cle Elum Lake reservoir records, accessed 2026-09-02, hydrionis.com/reservoirs/reservoir-usbr-7170/

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 Cle Elum 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

1,439 monthly observations 1906–2026 Mm³

Spatially aggregatedHigh confidenceAugust 2026

Source: USBR — Reservoir operations and Colorado River data, RISE catalogue item 129798. 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.