Lake Lowell (Reclamation) — storage

Storage now, against this reservoir's own record

131.63 Mm³

Stored, August 2026

97th

Percentile among 76 Augs on record

+59.2%

Against the Aug 1991–2020 average

+8.3%

Change over the 12 months to 2026-08

Storage in August 2026 was higher than almost every other Aug on record, ranked against 76 other Augs held for this reservoir.

Storage, 1950–2026

Monthly mean storage

911 monthly values, 1950 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 911 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 911 would be longer than this page and unusable with a screen reader.
Period	Lake Lowell (Reclamation) (Mm³)
October 1950	70.4
February 1951	126
June 1951	200
September 1951	55.7
January 1952	119
May 1952	199
September 1952	54.4
January 1953	118
April 1953	213
August 1953	91.2
December 1953	105
April 1954	200
August 1954	61.9
November 1954	114
March 1955	149
July 1955	90.2
November 1955	72.2
March 1956	155
July 1956	114
October 1956	100
February 1957	139
June 1957	164
October 1957	94.0
February 1958	178
May 1958	198
September 1958	94.5
January 1959	125
May 1959	205
September 1959	31.1
December 1959	18.8
April 1960	196
August 1960	72.4
December 1960	129
April 1961	196
July 1961	135
November 1961	74.6
March 1962	179
July 1962	140
November 1962	134
February 1963	148
June 1963	196
October 1963	132
February 1964	159
June 1964	204
October 1964	155
January 1965	166
May 1965	204
September 1965	157
January 1966	163
May 1966	134
August 1966	56.7
December 1966	46.3
April 1967	185
August 1967	120
December 1967	152
March 1968	173
July 1968	147
November 1968	168
March 1969	168
July 1969	180
October 1969	158
February 1970	168
June 1970	192
October 1970	131
February 1971	146
May 1971	175
September 1971	87.9
January 1972	150
May 1972	164
September 1972	52.2
January 1973	146
April 1973	188
August 1973	50.1
December 1973	96.2
April 1974	182
August 1974	47.7
November 1974	127
March 1975	171
July 1975	133
November 1975	146
March 1976	181
June 1976	140
October 1976	132
February 1977	141
June 1977	105
October 1977	22.5
January 1978	44.4
May 1978	202
September 1978	125
January 1979	149
May 1979	172
August 1979	37.1
December 1979	93.4
April 1980	195
August 1980	91.4
December 1980	138
April 1981	198
July 1981	144
November 1981	114
March 1982	128
July 1982	175
November 1982	159
February 1983	161
June 1983	174
October 1983	156
February 1984	163
June 1984	191
September 1984	101
January 1985	143
May 1985	162
September 1985	79.0
January 1986	153
April 1986	188
August 1986	70.5
December 1986	140
April 1987	165
August 1987	83.8
November 1987	83.7
March 1988	99.3
July 1988	85.2
November 1988	75.0
March 1989	124
July 1989	85.6
October 1989	108
February 1990	111
June 1990	108
October 1990	41.0
February 1991	54.5
May 1991	123
September 1991	56.7
January 1992	69.1
May 1992	39.1
September 1992	13.5
December 1992	36.7
April 1993	121
August 1993	84.1
December 1993	46.6
April 1994	160
July 1994	71.8
November 1994	22.9
March 1995	96.5
July 1995	151
November 1995	123
February 1996	178
June 1996	167
October 1996	126
February 1997	130
June 1997	162
October 1997	142
January 1998	142
May 1998	174
September 1998	95.1
January 1999	136
May 1999	186
August 1999	94.4
December 1999	128
April 2000	160
August 2000	72.0
December 2000	121
March 2001	119
July 2001	53.0
November 2001	34.8
March 2002	78.1
July 2002	84.6
October 2002	68.9
February 2003	81.7
June 2003	142
October 2003	133
February 2004	166
May 2004	143
September 2004	117
January 2005	140
May 2005	132
September 2005	89.5
January 2006	107
April 2006	113
August 2006	75.9
December 2006	120
April 2007	121
August 2007	64.3
November 2007	98.8
March 2008	98.2
July 2008	73.3
November 2008	113
March 2009	126
June 2009	165
October 2009	128
February 2010	141
June 2010	173
October 2010	121
January 2011	151
May 2011	174
September 2011	90.6
January 2012	148
May 2012	170
August 2012	79.9
December 2012	149
April 2013	156
August 2013	54.1
December 2013	43.6
April 2014	118
July 2014	77.9
November 2014	113
March 2015	138
July 2015	127
November 2015	123
February 2016	122
June 2016	169
October 2016	121
February 2017	123
June 2017	185
September 2017	105
January 2018	146
May 2018	188
September 2018	94.7
January 2019	117
April 2019	186
August 2019	114
December 2019	132
April 2020	162
August 2020	117
November 2020	132
March 2021	131
July 2021	120
November 2021	94.5
March 2022	95.0
July 2022	112
October 2022	99.0
February 2023	99.4
June 2023	160
October 2023	147
February 2024	143
May 2024	170
September 2024	96.4
January 2025	128
May 2025	186
September 2025	125
December 2025	139
April 2026	151
August 2026	132

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	110	138
Feb	114	137
Mar	127	136
Apr	149	151
May	153	165
Jun	145	152
Jul	114	146
Aug	82.7	132
Sep	81.0	125
Oct	103	140
Nov	109	139
Dec	110	139

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

875 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 875 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 875 would be longer than this page and unusable with a screen reader.
Period	Lake Lowell (Reclamation) (m)
1953.75	767
1954.0833333333333	768
1954.3333333333333	770
1954.6666666666667	767
1955	769
1955.25	770
1955.5833333333333	765
1955.9166666666667	767
1956.1666666666667	770
1956.5	768
1956.8333333333333	768
1957.0833333333333	769
1957.4166666666667	770
1957.75	768
1958	769
1958.3333333333333	771
1958.6666666666667	768
1958.9166666666667	769
1959.25	771
1959.5	769
1959.8333333333333	764
1960.1666666666667	769
1960.4166666666667	770
1960.75	768
1961.0833333333333	769
1961.3333333333333	770
1961.6666666666667	767
1962	769
1962.25	771
1962.5833333333333	768
1962.9166666666667	769
1963.1666666666667	771
1963.5	770
1963.8333333333333	769
1964.0833333333333	770
1964.4166666666667	771
1964.75	770
1965	770
1965.3333333333333	771
1965.6666666666667	770
1965.9166666666667	770
1966.25	770
1966.5833333333333	766
1966.8333333333333	765
1967.1666666666667	770
1967.5	770
1967.75	769
1968.0833333333333	770
1968.4166666666667	771
1968.6666666666667	769
1969	770
1969.3333333333333	771
1969.5833333333333	769
1969.9166666666667	770
1970.1666666666667	770
1970.5	770
1970.8333333333333	769
1971.0833333333333	769
1971.4166666666667	770
1971.75	769
1972	770
1972.3333333333333	770
1972.6666666666667	766
1972.9166666666667	768
1973.25	771
1973.5833333333333	766
1973.8333333333333	766
1974.1666666666667	770
1974.5	768
1974.75	768
1975.0833333333333	769
1975.4166666666667	770
1975.6666666666667	766
1976	769
1976.3333333333333	770
1976.5833333333333	767
1976.9166666666667	769
1977.25	769
1977.5	767
1977.8333333333333	765
1978.1666666666667	770
1978.4166666666667	770
1978.75	769
1979.0833333333333	770
1979.3333333333333	770
1979.6666666666667	766
1979.9166666666667	768
1980.25	771
1980.5833333333333	768
1980.8333333333333	769
1981.1666666666667	770
1981.5	769
1981.75	768
1982.0833333333333	769
1982.4166666666667	771
1982.6666666666667	769
1983	770
1983.3333333333333	771
1983.5833333333333	768
1983.9166666666667	770
1984.25	770
1984.5	769
1984.8333333333333	769
1985.1666666666667	769
1985.4166666666667	770
1985.75	769
1986.0833333333333	770
1986.3333333333333	771
1986.6666666666667	768
1987	769
1987.25	770
1987.5833333333333	767
1987.9166666666667	767
1988.1666666666667	768
1988.5	767
1988.8333333333333	767
1989.0833333333333	767
1989.4166666666667	769
1989.75	768
1990	768
1990.3333333333333	769
1990.5833333333333	766
1990.9166666666667	766
1991.25	769
1991.5	767
1991.8333333333333	767
1992.1666666666667	767
1992.4166666666667	765
1992.75	764
1993.0833333333333	766
1993.3333333333333	769
1993.6666666666667	766
1994	766
1994.25	770
1994.5833333333333	765
1994.9166666666667	765
1995.1666666666667	768
1995.5	770
1995.8333333333333	769
1996.0833333333333	771
1996.4166666666667	771
1996.75	769
1997	770
1997.3333333333333	770
1997.6666666666667	769
1997.9166666666667	770
1998.25	771
1998.5833333333333	769
1998.8333333333333	770
1999.1666666666667	771
1999.5	770
1999.75	769
2000.0833333333333	769
2000.4166666666667	770
2000.6666666666667	768
2001	769
2001.25	769
2001.5833333333333	766
2001.9166666666667	766
2002.1666666666667	768
2002.5	768
2002.8333333333333	767
2003.0833333333333	768
2003.4166666666667	770
2003.75	770
2004	770
2004.3333333333333	770
2004.6666666666667	769
2004.9166666666667	770
2005.25	770
2005.5833333333333	769
2005.8333333333333	769
2006.1666666666667	769
2006.5	769
2006.75	768
2007.0833333333333	769
2007.4166666666667	769
2007.6666666666667	767
2008	768
2008.3333333333333	769
2008.5833333333333	767
2008.9166666666667	769
2009.25	771
2009.5	770
2009.8333333333333	770
2010.1666666666667	770
2010.4166666666667	771
2010.75	769
2011	770
2011.3333333333333	771
2011.6666666666667	768
2011.9166666666667	770
2012.25	770
2012.5833333333333	768
2012.8333333333333	770
2013.1666666666667	770
2013.5	768
2013.75	766
2014.0833333333333	766
2014.4166666666667	769
2014.6666666666667	767
2015	769
2015.3333333333333	771
2015.5833333333333	769
2015.9166666666667	769
2016.25	771
2016.5	770
2016.8333333333333	769
2017.1666666666667	770
2017.4166666666667	771
2017.75	770
2018.0833333333333	770
2018.3333333333333	771
2018.6666666666667	768
2019	769
2019.25	771
2019.5833333333333	769
2019.9166666666667	770
2020.1666666666667	770
2020.5	770
2020.8333333333333	770
2021.0833333333333	770
2021.4166666666667	770
2021.6666666666667	768
2022	768
2022.3333333333333	769
2022.5833333333333	768
2022.9166666666667	768
2023.25	770
2023.5	770
2023.8333333333333	770
2024.1666666666667	770
2024.4166666666667	770
2024.75	770
2025.0833333333333	769
2025.3333333333333	771
2025.6666666666667	769
2026	770
2026.25	770
2026.5833333333333	770

Rate and persistence

+0.84 Mm³

Mean change per month over 12 months

0 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

Lake Lowell (Reclamation)

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	1950–2026
Completeness	98.6% 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 1950 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-7188.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), Lake Lowell (Reclamation) reservoir records, accessed 2026-09-02, hydrionis.com/reservoirs/reservoir-usbr-7188/

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 Lake Lowell (Reclamation) 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

911 monthly observations 1950–2026 Mm³

Spatially aggregatedHigh confidenceAugust 2026

Source: USBR — Reservoir operations and Colorado River data, RISE catalogue item 131590. 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.