Clear Lake Reservoir East Lobe — storage

Storage now, against this reservoir's own record

72.60 Mm³

Stored, September 2014

22nd

Percentile among 28 Seps on record

-56.7%

Against the Sep 1991–2020 average

-3.2%

Change over the 12 months to 2014-09

Storage in September 2014 was lower than most Seps on record, ranked against 28 other Seps held for this reservoir.

Storage, 1986–2014

Monthly mean storage

260 monthly values, 1986 to 2014

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 260 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 260 would be longer than this page and unusable with a screen reader.
Period	Clear Lake Reservoir East Lobe (Mm³)
April 1986	522
May 1986	510
June 1986	489
July 1986	460
August 1986	427
September 1986	403
June 1987	369
July 1987	350
August 1987	324
September 1987	301
April 1988	324
May 1988	319
June 1988	302
July 1988	277
August 1988	245
September 1988	222
May 1989	381
June 1989	362
August 1989	313
September 1989	288
May 1990	279
June 1990	262
July 1990	236
August 1990	210
September 1990	190
May 1991	171
June 1991	154
July 1991	134
August 1991	106
September 1991	89.4
July 1992	54.4
May 1993	237
June 1993	225
July 1993	205
August 1993	184
September 1993	166
April 1994	157
May 1994	148
June 1994	132
July 1994	107
August 1994	83.9
September 1994	69.7
July 1995	321
August 1995	295
September 1995	270
May 1996	459
June 1996	450
July 1996	425
August 1996	397
September 1996	372
February 1997	476
April 1997	486
May 1997	482
June 1997	464
August 1997	412
September 1997	387
October 1997	375
April 1998	496
May 1998	498
June 1998	492
July 1998	474
August 1998	445
September 1998	420
October 1998	401
November 1998	401
December 1998	419
February 1999	439
March 1999	458
April 1999	465
May 1999	476
June 1999	459
July 1999	432
August 1999	405
September 1999	383
October 1999	370
November 1999	366
December 1999	365
January 2000	369
March 2000	410
April 2000	432
May 2000	429
June 2000	407
July 2000	380
August 2000	350
September 2000	318
October 2000	292
November 2000	292
December 2000	294
January 2001	294
February 2001	294
April 2001	297
May 2001	283
June 2001	250
July 2001	216
August 2001	186
September 2001	158
October 2001	147
November 2001	148
December 2001	156
January 2002	174
February 2002	180
March 2002	194
May 2002	215
June 2002	194
July 2002	171
August 2002	143
September 2002	122
October 2002	112
November 2002	110
December 2002	113
January 2003	121
February 2003	130
March 2003	136
April 2003	151
June 2003	147
July 2003	119
August 2003	90.1
September 2003	51.7
October 2003	74.0
November 2003	73.0
December 2003	77.7
January 2004	85.0
February 2004	103
March 2004	145
April 2004	165
May 2004	158
July 2004	113
August 2004	73.5
September 2004	35.5
October 2004	67.7
November 2004	69.5
December 2004	73.1
January 2005	78.3
February 2005	81.2
March 2005	84.8
April 2005	87.7
May 2005	116
June 2005	122
August 2005	69.1
September 2005	58.8
October 2005	67.2
November 2005	74.2
December 2005	93.5
January 2006	154
February 2006	193
March 2006	229
April 2006	283
May 2006	318
June 2006	301
July 2006	276
September 2006	222
October 2006	209
November 2006	208
December 2006	208
January 2007	208
February 2007	211
March 2007	217
April 2007	220
May 2007	209
June 2007	187
July 2007	160
August 2007	133
October 2007	104
November 2007	103
December 2007	104
January 2008	109
February 2008	112
March 2008	144
April 2008	182
May 2008	185
June 2008	179
July 2008	154
August 2008	128
September 2008	105
November 2008	96.4
December 2008	95.3
January 2009	97.7
February 2009	101
March 2009	110
April 2009	110
May 2009	99.9
June 2009	77.5
July 2009	58.8
August 2009	63.8
September 2009	69.0
October 2009	69.1
December 2009	71.0
January 2010	73.9
February 2010	79.7
March 2010	78.7
April 2010	81.7
May 2010	85.0
June 2010	81.0
July 2010	72.7
August 2010	73.8
September 2010	74.5
October 2010	74.2
November 2010	75.4
January 2011	106
February 2011	101
March 2011	137
April 2011	186
May 2011	232
June 2011	227
July 2011	208
August 2011	183
September 2011	161
October 2011	151
November 2011	147
December 2011	145
February 2012	146
March 2012	151
April 2012	158
May 2012	152
June 2012	134
July 2012	112
August 2012	84.0
September 2012	69.4
October 2012	72.6
November 2012	75.2
December 2012	93.2
January 2013	92.1
March 2013	122
April 2013	126
May 2013	115
June 2013	99.2
July 2013	68.1
August 2013	74.0
September 2013	75.0
October 2013	74.2
November 2013	75.1
December 2013	76.6
January 2014	75.2
February 2014	76.1
April 2014	77.3
May 2014	72.9
June 2014	71.3
July 2014	71.1
August 2014	72.0
September 2014	72.6

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	—	75.2
Feb	—	76.1
Mar	—	83.4
Apr	—	77.3
May	241	72.9
Jun	225	71.3
Jul	203	71.1
Aug	187	72.0
Sep	168	72.6
Oct	—	74.2
Nov	—	75.1
Dec	—	76.6

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

402 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 402 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 402 would be longer than this page and unusable with a screen reader.
Period	Clear Lake Reservoir East Lobe (m)
1986.25	1,384
1986.4166666666667	1,383
1986.5	1,383
1986.6666666666667	1,382
1987.4166666666667	1,382
1987.5	1,382
1987.6666666666667	1,381
1988.3333333333333	1,381
1988.4166666666667	1,381
1988.5833333333333	1,381
1989.3333333333333	1,382
1989.4166666666667	1,382
1989.5833333333333	1,381
1990.3333333333333	1,381
1990.4166666666667	1,381
1990.5833333333333	1,380
1991.3333333333333	1,380
1991.5	1,379
1991.5833333333333	1,379
1992.4166666666667	1,378
1993.3333333333333	1,381
1993.4166666666667	1,380
1993.5833333333333	1,380
1994.25	1,380
1994.3333333333333	1,379
1994.5	1,379
1994.6666666666667	1,378
1995.4166666666667	1,382
1995.5833333333333	1,381
1996.3333333333333	1,383
1996.4166666666667	1,383
1996.5833333333333	1,382
1997.0833333333333	1,383
1997.25	1,383
1997.4166666666667	1,383
1997.5833333333333	1,382
1997.6666666666667	1,382
1998.25	1,383
1998.4166666666667	1,383
1998.5	1,383
1998.6666666666667	1,383
1998.8333333333333	1,382
1998.9166666666667	1,383
1999.0833333333333	1,383
1999.25	1,383
1999.4166666666667	1,383
1999.5	1,383
1999.6666666666667	1,382
1999.8333333333333	1,382
1999.9166666666667	1,382
2000.0833333333333	1,382
2000.25	1,383
2000.3333333333333	1,383
2000.5	1,382
2000.6666666666667	1,381
2000.75	1,381
2000.9166666666667	1,381
2001.0833333333333	1,381
2001.1666666666667	1,381
2001.3333333333333	1,381
2001.5	1,380
2001.5833333333333	1,380
2001.75	1,379
2001.9166666666667	1,380
2002	1,380
2002.1666666666667	1,380
2002.3333333333333	1,380
2002.4166666666667	1,380
2002.5833333333333	1,379
2002.75	1,379
2002.8333333333333	1,379
2003	1,379
2003.1666666666667	1,379
2003.25	1,379
2003.4166666666667	1,379
2003.5833333333333	1,379
2003.75	1,378
2003.8333333333333	1,378
2004	1,379
2004.1666666666667	1,379
2004.25	1,380
2004.4166666666667	1,379
2004.5833333333333	1,378
2004.6666666666667	1,377
2004.8333333333333	1,378
2005	1,378
2005.0833333333333	1,378
2005.25	1,379
2005.4166666666667	1,379
2005.5	1,379
2005.6666666666667	1,378
2005.8333333333333	1,378
2005.9166666666667	1,379
2006.0833333333333	1,380
2006.25	1,381
2006.3333333333333	1,381
2006.5	1,381
2006.6666666666667	1,380
2006.75	1,380
2006.9166666666667	1,380
2007.0833333333333	1,380
2007.1666666666667	1,380
2007.3333333333333	1,380
2007.5	1,380
2007.5833333333333	1,379
2007.75	1,379
2007.9166666666667	1,379
2008.0833333333333	1,379
2008.1666666666667	1,379
2008.3333333333333	1,380
2008.5	1,380
2008.5833333333333	1,379
2008.75	1,379
2008.9166666666667	1,379
2009	1,379
2009.1666666666667	1,379
2009.3333333333333	1,379
2009.4166666666667	1,378
2009.5833333333333	1,378
2009.75	1,378
2009.8333333333333	1,378
2010	1,378
2010.1666666666667	1,378
2010.25	1,378
2010.4166666666667	1,378
2010.5833333333333	1,378
2010.6666666666667	1,378
2010.8333333333333	1,378
2011	1,379
2011.0833333333333	1,379
2011.25	1,380
2011.4166666666667	1,380
2011.5	1,380
2011.6666666666667	1,380
2011.8333333333333	1,379
2012	1,379
2012.0833333333333	1,379
2012.25	1,380
2012.4166666666667	1,379
2012.5	1,379
2012.6666666666667	1,378
2012.8333333333333	1,378
2012.9166666666667	1,379
2013.0833333333333	1,379
2013.25	1,379
2013.3333333333333	1,379
2013.5	1,378
2013.6666666666667	1,378
2013.75	1,378
2013.9166666666667	1,378
2014.0833333333333	1,378
2014.1666666666667	1,378
2014.3333333333333	1,378
2014.5	1,378
2014.5833333333333	1,378
2014.75	1,378
2014.9166666666667	1,379
2015	1,379
2015.1666666666667	1,378
2015.3333333333333	1,378
2015.4166666666667	1,378
2015.5833333333333	1,378
2015.75	1,378
2015.8333333333333	1,378
2016	1,379
2016.1666666666667	1,379
2016.3333333333333	1,379
2016.4166666666667	1,379
2016.5833333333333	1,378
2016.75	1,378
2016.8333333333333	1,378
2017	1,379
2017.1666666666667	1,381
2017.25	1,382
2017.4166666666667	1,382
2017.5833333333333	1,381
2017.75	1,381
2017.9166666666667	1,381
2018.0833333333333	1,381
2018.1666666666667	1,381
2018.3333333333333	1,381
2018.5	1,380
2018.5833333333333	1,380
2018.75	1,380
2018.9166666666667	1,380
2019	1,380
2019.1666666666667	1,381
2019.3333333333333	1,382
2019.4166666666667	1,382
2019.5833333333333	1,381
2019.75	1,381
2019.8333333333333	1,381
2020	1,381
2020.1666666666667	1,381
2020.25	1,381
2020.4166666666667	1,380
2020.5833333333333	1,380
2020.75	1,379
2020.8333333333333	1,379
2021	1,379
2021.1666666666667	1,379
2021.25	1,379
2021.4166666666667	1,379
2021.5833333333333	1,378
2021.6666666666667	1,378
2021.8333333333333	1,378
2022	1,379
2022.0833333333333	1,378
2022.25	1,379
2022.4166666666667	1,378
2022.5	1,378
2022.6666666666667	1,378
2022.8333333333333	1,378
2022.9166666666667	1,378
2023.0833333333333	1,379
2023.25	1,379
2023.3333333333333	1,380
2023.5	1,379
2023.6666666666667	1,379
2023.75	1,379
2023.9166666666667	1,379
2024.0833333333333	1,379
2024.1666666666667	1,379
2024.3333333333333	1,380
2024.5	1,379
2024.6666666666667	1,378
2024.75	1,378
2024.9166666666667	1,378
2025.0833333333333	1,379
2025.1666666666667	1,380
2025.3333333333333	1,381
2025.5	1,380
2025.5833333333333	1,380
2025.75	1,379
2025.9166666666667	1,379
2026	1,380
2026.1666666666667	1,380
2026.3333333333333	1,380
2026.4166666666667	1,380
2026.5833333333333	1,379

Rate and persistence

-0.20 Mm³

Mean drawdown per month over 12 months

15 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

Clear Lake Reservoir East Lobe

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	1986–2014
Completeness	74.7% 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	75% of the months between 1986 and 2014 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-7309.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), Clear Lake Reservoir East Lobe reservoir records, accessed 2026-09-02, hydrionis.com/reservoirs/reservoir-usbr-7309/

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 Clear Lake Reservoir East Lobe 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

260 monthly observations 1986–2014 Mm³

Spatially aggregatedHigh confidenceSeptember 2014

Source: USBR — Reservoir operations and Colorado River data, RISE catalogue item 134050. 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.