Potholes Reservoir — storage

Storage now, against this reservoir's own record

107.53 Mm³

Stored, August 2026

63rd

Percentile among 71 Augs on record

+0.8%

Against the Aug 1991–2020 average

+35.0%

Change over the 12 months to 2026-08

Storage in August 2026 was around the middle of the Aug record, ranked against 71 other Augs held for this reservoir.

Storage, 1953–2026

Monthly mean storage

805 monthly values, 1953 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 805 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 805 would be longer than this page and unusable with a screen reader.
Period	Potholes Reservoir (Mm³)
August 1953	13.3
November 1953	28.3
March 1954	43.8
January 1955	24.3
April 1955	48.5
August 1955	80.7
November 1955	98.9
March 1956	283
June 1956	278
September 1956	188
May 1958	255
August 1958	92.6
December 1958	173
April 1959	325
July 1959	197
October 1959	160
February 1960	289
May 1960	251
September 1960	79.9
January 1961	263
June 1961	198
October 1961	73.4
May 1962	188
August 1962	31.1
December 1962	184
June 1963	181
September 1963	68.1
January 1964	238
April 1964	252
August 1964	21.0
November 1964	106
February 1965	245
June 1965	124
October 1965	42.4
January 1966	230
June 1966	122
September 1966	45.3
December 1966	214
April 1967	304
July 1967	252
November 1967	237
February 1968	418
May 1968	316
September 1968	139
March 1969	450
June 1969	381
October 1969	180
February 1970	362
May 1970	362
September 1970	55.7
December 1970	217
April 1971	363
July 1971	157
October 1971	34.9
February 1972	288
May 1972	217
August 1972	57.7
December 1972	221
March 1973	369
June 1973	155
October 1973	135
January 1974	378
May 1974	391
August 1974	117
November 1974	182
March 1975	447
June 1975	294
September 1975	112
January 1976	345
April 1976	426
July 1976	181
January 1977	301
April 1977	433
August 1977	57.1
November 1977	220
February 1978	406
June 1978	340
September 1978	119
December 1978	274
April 1979	428
July 1979	143
October 1979	157
February 1980	442
May 1980	388
September 1980	134
December 1980	314
May 1981	397
September 1981	34.4
April 1982	366
July 1982	184
March 1983	409
June 1983	267
September 1983	98.2
March 1984	477
June 1984	344
October 1984	116
May 1985	327
August 1985	62.3
April 1986	431
July 1986	184
October 1986	98.5
June 1987	326
September 1987	38.4
April 1988	359
August 1988	87.3
January 1989	260
May 1989	449
August 1989	111
November 1989	155
March 1990	348
June 1990	351
September 1990	69.7
January 1991	252
April 1991	371
July 1991	212
November 1991	175
February 1992	345
June 1992	345
September 1992	86.3
December 1992	235
April 1993	425
July 1993	215
October 1993	61.5
February 1994	331
May 1994	442
September 1994	42.2
December 1994	272
March 1995	410
July 1995	250
October 1995	99.9
January 1996	335
May 1996	404
August 1996	70.6
November 1996	162
March 1997	436
June 1997	322
October 1997	117
January 1998	340
April 1998	396
August 1998	45.4
November 1998	154
February 1999	348
June 1999	341
September 1999	55.8
December 1999	235
April 2000	386
July 2000	265
November 2000	181
February 2001	348
May 2001	369
September 2001	52.9
December 2001	234
March 2002	341
July 2002	235
October 2002	50.4
January 2003	247
May 2003	457
August 2003	93.5
December 2003	209
March 2004	328
June 2004	417
October 2004	146
January 2005	358
April 2005	388
August 2005	76.7
November 2005	239
February 2006	398
June 2006	406
September 2006	67.3
January 2007	322
April 2007	386
July 2007	250
November 2007	224
February 2008	397
May 2008	454
September 2008	63.8
December 2008	272
March 2009	388
July 2009	204
October 2009	103
February 2010	374
May 2010	434
August 2010	136
December 2010	272
March 2011	385
June 2011	425
October 2011	68.0
January 2012	307
April 2012	396
August 2012	142
November 2012	187
March 2013	372
June 2013	398
September 2013	68.5
January 2014	301
April 2014	384
July 2014	228
November 2014	205
February 2015	373
May 2015	427
September 2015	68.5
December 2015	254
April 2016	405
July 2016	271
October 2016	136
February 2017	400
May 2017	421
August 2017	78.4
December 2017	299
March 2018	397
June 2018	336
October 2018	76.2
January 2019	321
May 2019	430
August 2019	131
November 2019	213
March 2020	365
June 2020	368
September 2020	65.8
January 2021	313
April 2021	310
July 2021	122
November 2021	193
February 2022	323
June 2022	409
September 2022	61.2
December 2022	288
April 2023	401
July 2023	170
October 2023	106
February 2024	379
May 2024	465
August 2024	82.7
December 2024	309
March 2025	406
July 2025	202
October 2025	114
January 2026	351
May 2026	476
August 2026	108

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	315	351
Feb	361	386
Mar	383	389
Apr	397	428
May	432	476
Jun	365	406
Jul	226	238
Aug	107	108
Sep	66.7	48.5
Oct	88.3	114
Nov	189	246
Dec	263	314

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

826 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 826 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 826 would be longer than this page and unusable with a screen reader.
Period	Potholes Reservoir (m)
1952.4166666666667	305
1952.6666666666667	310
1953	311
1953.3333333333333	310
1953.6666666666667	312
1953.9166666666667	313
1954.25	312
1954.5	310
1954.8333333333333	312
1955.0833333333333	313
1955.4166666666667	313
1955.6666666666667	314
1955.9166666666667	315
1956.25	318
1956.5	317
1958.1666666666667	317
1958.4166666666667	316
1958.75	314
1959.0833333333333	317
1959.4166666666667	317
1959.6666666666667	315
1959.9166666666667	316
1960.25	317
1960.5	315
1960.9166666666667	317
1961.3333333333333	317
1961.6666666666667	313
1962.25	317
1962.5833333333333	313
1962.8333333333333	315
1963.4166666666667	316
1963.6666666666667	314
1963.9166666666667	316
1964.25	317
1964.5	314
1964.8333333333333	314
1965.0833333333333	317
1965.4166666666667	315
1965.6666666666667	312
1966	316
1966.3333333333333	316
1966.6666666666667	313
1966.9166666666667	316
1967.1666666666667	317
1967.5	317
1967.75	315
1968.0833333333333	318
1968.3333333333333	317
1968.6666666666667	315
1969.1666666666667	319
1969.5	317
1969.75	316
1970.0833333333333	318
1970.4166666666667	317
1970.6666666666667	313
1971	317
1971.25	318
1971.5833333333333	313
1971.8333333333333	315
1972.1666666666667	317
1972.4166666666667	316
1972.75	314
1973	317
1973.25	318
1973.5833333333333	312
1973.8333333333333	316
1974.1666666666667	319
1974.4166666666667	317
1974.75	314
1975	318
1975.3333333333333	318
1975.5833333333333	315
1975.9166666666667	317
1976.1666666666667	319
1976.4166666666667	317
1976.75	314
1977.1666666666667	318
1977.5	316
1977.75	315
1978.0833333333333	318
1978.3333333333333	318
1978.6666666666667	315
1978.9166666666667	317
1979.25	318
1979.5	315
1979.75	315
1980.0833333333333	319
1980.3333333333333	318
1980.6666666666667	315
1980.9166666666667	317
1981.4166666666667	318
1981.6666666666667	313
1982.3333333333333	317
1982.5833333333333	314
1983.1666666666667	318
1983.5	316
1983.75	315
1984.25	319
1984.5	316
1985.1666666666667	319
1985.4166666666667	316
1985.75	314
1986.3333333333333	318
1986.6666666666667	313
1987.25	318
1987.5	316
1988.1666666666667	318
1988.4166666666667	318
1988.75	313
1989.1666666666667	318
1989.5	316
1989.75	314
1990.0833333333333	317
1990.3333333333333	318
1990.6666666666667	314
1990.9166666666667	316
1991.1666666666667	318
1991.5	316
1991.75	314
1992.0833333333333	318
1992.3333333333333	318
1992.6666666666667	314
1992.9166666666667	316
1993.25	318
1993.5	316
1993.75	313
1994.0833333333333	318
1994.3333333333333	319
1994.6666666666667	313
1994.9166666666667	317
1995.25	319
1995.5	317
1995.8333333333333	316
1996.0833333333333	318
1996.4166666666667	317
1996.6666666666667	313
1996.9166666666667	316
1997.25	319
1997.5	316
1997.8333333333333	316
1998.0833333333333	318
1998.4166666666667	316
1998.6666666666667	313
1999	317
1999.25	319
1999.5833333333333	314
1999.8333333333333	315
2000.0833333333333	318
2000.4166666666667	318
2000.6666666666667	314
2001	317
2001.25	318
2001.5833333333333	314
2001.8333333333333	315
2002.1666666666667	318
2002.4166666666667	318
2002.6666666666667	313
2003	317
2003.25	318
2003.5833333333333	314
2003.8333333333333	315
2004.1666666666667	317
2004.4166666666667	318
2004.75	315
2005	318
2005.3333333333333	319
2005.5833333333333	314
2005.8333333333333	316
2006.1666666666667	318
2006.4166666666667	318
2006.75	314
2007	317
2007.3333333333333	319
2007.5833333333333	315
2007.9166666666667	317
2008.1666666666667	318
2008.5	316
2008.75	314
2009	318
2009.3333333333333	319
2009.5833333333333	314
2009.9166666666667	317
2010.1666666666667	318
2010.5	317
2010.75	314
2011.0833333333333	318
2011.3333333333333	319
2011.6666666666667	313
2011.9166666666667	317
2012.1666666666667	318
2012.5	317
2012.75	314
2013.0833333333333	318
2013.3333333333333	319
2013.6666666666667	314
2013.9166666666667	317
2014.25	318
2014.5	316
2014.75	314
2015.0833333333333	318
2015.3333333333333	318
2015.6666666666667	314
2015.9166666666667	317
2016.25	318
2016.5	317
2016.8333333333333	317
2017.0833333333333	318
2017.4166666666667	318
2017.6666666666667	314
2017.9166666666667	317
2018.25	318
2018.5	316
2018.8333333333333	316
2019.0833333333333	318
2019.4166666666667	318
2019.6666666666667	314
2020	318
2020.25	318
2020.5833333333333	314
2020.8333333333333	316
2021.0833333333333	318
2021.4166666666667	317
2021.6666666666667	314
2022	317
2022.25	317
2022.5833333333333	314
2022.8333333333333	316
2023.1666666666667	318
2023.4166666666667	318
2023.6666666666667	313
2024	318
2024.25	318
2024.5833333333333	314
2024.8333333333333	316
2025.1666666666667	318
2025.4166666666667	318
2025.75	315
2026	318
2026.3333333333333	319
2026.5833333333333	314

Rate and persistence

+2.32 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

Potholes Reservoir

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	1953–2026
Completeness	90.7% 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	91% of the months between 1953 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-7265.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), Potholes Reservoir reservoir records, accessed 2026-09-02, hydrionis.com/reservoirs/reservoir-usbr-7265/

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 Potholes Reservoir 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

805 monthly observations 1953–2026 Mm³

Spatially aggregatedHigh confidenceAugust 2026

Source: USBR — Reservoir operations and Colorado River data, RISE catalogue item 132563. 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.