Lake Lowell (Reclamation) — storage

Storage now, against this reservoir's own record

135.15 Mm³

Stored, September 2026

97th

Percentile among 76 Seps on record

+67.0%

Against the Sep 1991–2020 average

+8.0%

Change over the 12 months to 2026-09

Storage in September 2026 was higher than almost every other Sep on record, ranked against 76 other Seps held for this reservoir.

Storage, 1950–2026

Monthly mean storage

912 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 912 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 912 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
December 1954	117
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
January 1960	18.8
April 1960	196
August 1960	72.4
December 1960	129
April 1961	196
August 1961	80.6
November 1961	74.6
March 1962	179
July 1962	140
November 1962	134
March 1963	187
June 1963	196
October 1963	132
February 1964	159
June 1964	204
October 1964	155
February 1965	192
May 1965	204
September 1965	157
January 1966	163
May 1966	134
September 1966	35.6
December 1966	46.3
April 1967	185
August 1967	120
December 1967	152
April 1968	177
July 1968	147
November 1968	168
March 1969	168
July 1969	180
November 1969	166
March 1970	167
June 1970	192
October 1970	131
February 1971	146
June 1971	177
October 1971	137
January 1972	150
May 1972	164
September 1972	52.2
January 1973	146
May 1973	178
August 1973	50.1
December 1973	96.2
April 1974	182
August 1974	47.7
December 1974	139
April 1975	189
July 1975	133
November 1975	146
March 1976	181
July 1976	89.7
November 1976	142
February 1977	141
June 1977	105
October 1977	22.5
February 1978	102
June 1978	179
September 1978	125
January 1979	149
May 1979	172
September 1979	61.5
January 1980	96.0
April 1980	195
August 1980	91.4
December 1980	138
April 1981	198
August 1981	84.0
December 1981	116
March 1982	128
July 1982	175
November 1982	159
March 1983	160
July 1983	145
October 1983	156
February 1984	163
June 1984	191
October 1984	138
February 1985	143
May 1985	162
September 1985	79.0
January 1986	153
May 1986	191
September 1986	89.8
January 1987	140
April 1987	165
August 1987	83.8
December 1987	86.0
April 1988	128
August 1988	60.9
November 1988	75.0
March 1989	124
July 1989	85.6
November 1989	111
March 1990	112
June 1990	108
October 1990	41.0
February 1991	54.5
June 1991	99.8
October 1991	60.6
February 1992	69.8
May 1992	39.1
September 1992	13.5
January 1993	48.2
May 1993	140
September 1993	51.4
December 1993	46.6
April 1994	160
August 1994	30.2
December 1994	27.3
April 1995	158
July 1995	151
November 1995	123
March 1996	175
July 1996	126
November 1996	129
March 1997	144
June 1997	162
October 1997	142
February 1998	142
June 1998	180
October 1998	128
January 1999	136
May 1999	186
September 1999	98.6
January 2000	128
May 2000	177
August 2000	72.0
December 2000	121
April 2001	117
August 2001	36.7
December 2001	34.7
March 2002	78.1
July 2002	84.6
November 2002	71.5
March 2003	96.2
July 2003	113
November 2003	130
February 2004	166
June 2004	128
October 2004	144
February 2005	137
June 2005	145
September 2005	89.5
January 2006	107
May 2006	120
September 2006	75.2
January 2007	119
April 2007	121
August 2007	64.3
December 2007	98.4
April 2008	102
August 2008	57.3
December 2008	111
March 2009	126
July 2009	133
November 2009	144
March 2010	138
July 2010	132
October 2010	121
February 2011	149
June 2011	182
October 2011	127
February 2012	147
May 2012	170
September 2012	83.1
January 2013	147
May 2013	143
September 2013	38.8
January 2014	45.2
April 2014	118
August 2014	51.7
December 2014	114
April 2015	178
August 2015	100
November 2015	123
March 2016	155
July 2016	138
November 2016	120
March 2017	151
June 2017	185
October 2017	143
February 2018	144
June 2018	183
October 2018	114
February 2019	117
May 2019	189
September 2019	111
January 2020	131
May 2020	169
September 2020	116
December 2020	131
April 2021	153
August 2021	102
December 2021	95.4
April 2022	98.6
July 2022	112
November 2022	98.1
March 2023	101
July 2023	136
November 2023	146
March 2024	141
June 2024	155
October 2024	132
February 2025	129
June 2025	173
October 2025	140
January 2026	138
May 2026	165
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	110	138
Feb	114	137
Mar	127	136
Apr	149	151
May	153	165
Jun	145	152
Jul	114	146
Aug	82.7	131
Sep	81.0	135
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

876 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 876 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 876 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
1959.5833333333333	766
1959.8333333333333	764
1960.1666666666667	769
1960.5	768
1960.75	768
1961.0833333333333	769
1961.4166666666667	770
1961.6666666666667	767
1962	769
1962.3333333333333	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
1970.25	771
1970.5	770
1970.8333333333333	769
1971.1666666666667	769
1971.4166666666667	770
1971.75	769
1972.0833333333333	770
1972.3333333333333	770
1972.6666666666667	766
1973	769
1973.25	771
1973.5833333333333	766
1973.9166666666667	768
1974.1666666666667	770
1974.5	768
1974.8333333333333	769
1975.0833333333333	769
1975.4166666666667	770
1975.75	768
1976	769
1976.3333333333333	770
1976.6666666666667	767
1976.9166666666667	769
1977.25	769
1977.5833333333333	765
1977.8333333333333	765
1978.1666666666667	770
1978.5	770
1978.75	769
1979.0833333333333	770
1979.4166666666667	769
1979.6666666666667	766
1980	768
1980.3333333333333	771
1980.5833333333333	768
1980.9166666666667	769
1981.1666666666667	770
1981.5	769
1981.8333333333333	768
1982.0833333333333	769
1982.4166666666667	771
1982.75	770
1983	770
1983.3333333333333	771
1983.6666666666667	769
1983.9166666666667	770
1984.25	770
1984.5833333333333	768
1984.8333333333333	769
1985.1666666666667	769
1985.5	767
1985.75	769
1986.0833333333333	770
1986.4166666666667	770
1986.6666666666667	768
1987	769
1987.3333333333333	769
1987.5833333333333	767
1987.9166666666667	767
1988.25	769
1988.5	767
1988.8333333333333	767
1989.1666666666667	769
1989.4166666666667	769
1989.75	768
1990.0833333333333	768
1990.3333333333333	769
1990.6666666666667	765
1991	766
1991.25	769
1991.5833333333333	766
1991.9166666666667	767
1992.1666666666667	767
1992.5	764
1992.8333333333333	764
1993.0833333333333	766
1993.4166666666667	769
1993.75	765
1994	766
1994.3333333333333	769
1994.6666666666667	764
1994.9166666666667	765
1995.25	770
1995.5833333333333	768
1995.8333333333333	769
1996.1666666666667	771
1996.5	769
1996.75	769
1997.0833333333333	770
1997.4166666666667	771
1997.6666666666667	769
1998	770
1998.3333333333333	771
1998.5833333333333	769
1998.9166666666667	770
1999.25	771
1999.5	770
1999.8333333333333	770
2000.0833333333333	769
2000.4166666666667	770
2000.75	769
2001	769
2001.3333333333333	769
2001.6666666666667	766
2001.9166666666667	766
2002.25	769
2002.5833333333333	767
2002.8333333333333	767
2003.1666666666667	768
2003.5	769
2003.75	770
2004.0833333333333	771
2004.4166666666667	769
2004.6666666666667	769
2005	770
2005.3333333333333	770
2005.5833333333333	769
2005.9166666666667	769
2006.25	769
2006.5	769
2006.8333333333333	769
2007.1666666666667	769
2007.4166666666667	769
2007.75	768
2008.0833333333333	768
2008.3333333333333	769
2008.6666666666667	767
2009	769
2009.25	771
2009.5833333333333	768
2009.9166666666667	770
2010.1666666666667	770
2010.5	770
2010.8333333333333	770
2011.0833333333333	770
2011.4166666666667	771
2011.75	769
2012	770
2012.3333333333333	771
2012.6666666666667	768
2012.9166666666667	770
2013.25	770
2013.5833333333333	767
2013.8333333333333	766
2014.1666666666667	768
2014.5	768
2014.75	769
2015.0833333333333	769
2015.4166666666667	771
2015.6666666666667	769
2016	769
2016.3333333333333	771
2016.5833333333333	769
2016.9166666666667	769
2017.25	771
2017.5	770
2017.8333333333333	770
2018.0833333333333	770
2018.4166666666667	771
2018.75	769
2019	769
2019.3333333333333	771
2019.6666666666667	769
2019.9166666666667	770
2020.25	771
2020.5833333333333	769
2020.8333333333333	770
2021.1666666666667	770
2021.5	769
2021.75	768
2022.0833333333333	768
2022.4166666666667	770
2022.6666666666667	768
2023	768
2023.3333333333333	770
2023.5833333333333	769
2023.9166666666667	770
2024.25	770
2024.5	768
2024.8333333333333	769
2025.1666666666667	770
2025.4166666666667	771
2025.75	770
2026.0833333333333	770
2026.3333333333333	739
2026.6666666666667	770

Rate and persistence

+0.83 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	98.7% 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	99% of the months between 1950 and 2026 are held. Monthly means of the publisher's own daily record.
Last read from the publisher	2026-10-01
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-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 2026-10-05, 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

912 monthly observations 1950–2026 Mm³

Spatially aggregatedHigh confidenceSeptember 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 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.