Bumping Lake And Bumping Lake — storage

Storage now, against this reservoir's own record

24.92 Mm³

Stored, August 2026

28th

Percentile among 115 Augs on record

-17.9%

Against the Aug 1991–2020 average

-4.9%

Change over the 12 months to 2026-08

Storage in August 2026 was lower than most Augs on record, ranked against 115 other Augs held for this reservoir.

Storage, 1912–2026

Monthly mean storage

1,376 monthly values, 1912 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 1,376 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,376 would be longer than this page and unusable with a screen reader.
Period	Bumping Lake And Bumping Lake (Mm³)
January 1912	1.76
July 1912	40.0
January 1913	1.45
June 1913	37.2
December 1913	2.14
June 1914	40.9
December 1914	6.28
May 1915	30.7
November 1915	3.71
May 1916	10.9
November 1916	7.43
April 1917	5.97
October 1917	2.73
April 1918	25.2
October 1918	3.46
March 1919	18.4
September 1919	15.5
March 1920	29.8
September 1920	13.6
February 1921	13.8
August 1921	43.2
February 1922	9.02
August 1922	30.6
January 1923	24.7
July 1923	46.6
January 1924	14.9
July 1924	41.7
December 1924	18.6
June 1925	47.6
December 1925	15.7
June 1926	45.5
November 1926	10.6
May 1927	29.7
November 1927	9.21
May 1928	41.3
October 1928	13.1
April 1929	6.36
October 1929	5.57
April 1930	37.3
September 1930	7.80
March 1931	19.7
September 1931	3.59
March 1932	29.6
August 1932	37.2
February 1933	17.3
August 1933	38.9
February 1934	34.4
July 1934	23.3
January 1935	34.7
July 1935	42.7
January 1936	3.60
June 1936	43.8
December 1936	4.63
June 1937	44.2
December 1937	19.2
May 1938	38.2
November 1938	5.68
May 1939	38.1
November 1939	3.27
April 1940	42.9
October 1940	3.23
April 1941	31.4
October 1941	3.50
March 1942	24.2
September 1942	11.0
March 1943	7.61
September 1943	13.0
February 1944	20.3
August 1944	17.8
February 1945	31.9
August 1945	22.9
January 1946	5.60
July 1946	42.2
January 1947	10.8
July 1947	34.9
December 1947	30.7
June 1948	44.6
December 1948	12.6
June 1949	44.3
November 1949	7.65
May 1950	16.5
November 1950	31.4
May 1951	33.6
November 1951	4.22
April 1952	13.7
October 1952	3.71
April 1953	16.9
October 1953	5.49
March 1954	16.2
September 1954	20.6
March 1955	22.0
September 1955	14.2
February 1956	3.98
August 1956	27.2
February 1957	20.8
August 1957	20.6
January 1958	9.62
July 1958	25.7
January 1959	13.8
July 1959	39.8
December 1959	19.7
June 1960	43.6
December 1960	13.1
June 1961	41.0
November 1961	7.14
May 1962	36.9
November 1962	7.17
May 1963	43.3
October 1963	3.66
April 1964	4.97
October 1964	6.20
April 1965	11.4
September 1965	12.4
March 1966	4.30
September 1966	10.1
March 1967	4.89
August 1967	29.4
February 1968	26.3
August 1968	25.4
February 1969	4.03
July 1969	40.5
January 1970	6.83
July 1970	37.7
January 1971	4.73
June 1971	26.3
December 1971	5.83
June 1972	42.6
December 1972	6.54
May 1973	28.0
November 1973	5.45
May 1974	14.8
November 1974	3.60
April 1975	3.59
October 1975	6.81
April 1976	8.09
October 1976	9.17
March 1977	14.5
September 1977	17.2
March 1978	23.7
September 1978	27.2
February 1979	7.49
August 1979	19.2
February 1980	13.6
August 1980	24.0
January 1981	28.6
July 1981	32.5
January 1982	5.00
July 1982	40.5
December 1982	8.50
June 1983	41.0
December 1983	4.19
June 1984	39.1
November 1984	4.81
May 1985	34.1
November 1985	10.8
May 1986	26.2
October 1986	6.48
April 1987	36.0
October 1987	7.63
April 1988	32.4
October 1988	8.24
March 1989	12.5
September 1989	22.9
March 1990	13.2
September 1990	20.0
February 1991	29.1
August 1991	29.9
February 1992	12.6
August 1992	28.7
January 1993	4.97
July 1993	33.1
January 1994	5.91
July 1994	30.1
December 1994	13.8
June 1995	38.8
December 1995	30.2
June 1996	43.4
November 1996	9.37
May 1997	26.3
November 1997	27.8
May 1998	41.9
October 1998	9.35
April 1999	7.86
October 1999	11.6
April 2000	26.0
September 2000	24.0
March 2001	4.39
September 2001	12.1
March 2002	20.7
August 2002	33.3
February 2003	26.9
August 2003	27.4
February 2004	14.0
July 2004	37.3
January 2005	27.1
July 2005	35.1
January 2006	25.5
June 2006	42.2
December 2006	19.3
June 2007	42.0
December 2007	22.1
May 2008	21.5
November 2008	16.3
May 2009	27.2
November 2009	17.9
April 2010	14.3
October 2010	18.3
April 2011	21.2
October 2011	24.8
March 2012	19.8
September 2012	27.5
March 2013	13.1
September 2013	23.6
February 2014	21.6
August 2014	33.0
February 2015	40.0
August 2015	27.5
January 2016	23.9
July 2016	36.4
January 2017	17.6
July 2017	39.1
December 2017	21.9
June 2018	41.7
December 2018	8.62
June 2019	40.9
November 2019	8.46
May 2020	38.1
November 2020	15.2
May 2021	35.7
October 2021	14.3
April 2022	27.8
October 2022	11.9
April 2023	15.5
September 2023	14.9
March 2024	32.0
September 2024	15.4
March 2025	14.0
August 2025	26.2
February 2026	26.9
August 2026	24.9

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	17.5	22.9
Feb	19.4	26.9
Mar	18.8	34.5
Apr	22.4	40.3
May	34.0	41.7
Jun	40.9	41.5
Jul	38.7	36.0
Aug	30.4	24.9
Sep	20.0	14.3
Oct	13.6	6.91
Nov	15.3	18.4
Dec	17.0	33.6

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

1,376 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 1,376 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,376 would be longer than this page and unusable with a screen reader.
Period	Bumping Lake And Bumping Lake (m)
1912	1,035
1912.5	1,044
1913	1,034
1913.4166666666667	1,044
1913.9166666666667	1,035
1914.4166666666667	1,045
1914.9166666666667	1,036
1915.3333333333333	1,042
1915.8333333333333	1,034
1916.3333333333333	1,037
1916.8333333333333	1,036
1917.25	1,035
1917.75	1,034
1918.25	1,041
1918.75	1,034
1919.1666666666667	1,039
1919.6666666666667	1,038
1920.1666666666667	1,042
1920.6666666666667	1,038
1921.0833333333333	1,038
1921.5833333333333	1,045
1922.0833333333333	1,036
1922.5833333333333	1,042
1923	1,041
1923.5	1,045
1924	1,038
1924.5	1,044
1924.9166666666667	1,039
1925.4166666666667	1,045
1925.9166666666667	1,038
1926.4166666666667	1,045
1926.8333333333333	1,037
1927.3333333333333	1,042
1927.8333333333333	1,036
1928.3333333333333	1,044
1928.75	1,038
1929.25	1,035
1929.75	1,035
1930.25	1,043
1930.6666666666667	1,036
1931.1666666666667	1,039
1931.6666666666667	1,034
1932.1666666666667	1,042
1932.5833333333333	1,043
1933.0833333333333	1,039
1933.5833333333333	1,044
1934.0833333333333	1,043
1934.5	1,040
1935	1,043
1935.5	1,044
1936	1,034
1936.4166666666667	1,045
1936.9166666666667	1,035
1937.4166666666667	1,045
1937.9166666666667	1,039
1938.3333333333333	1,044
1938.8333333333333	1,035
1939.3333333333333	1,044
1939.8333333333333	1,034
1940.25	1,044
1940.75	1,034
1941.25	1,042
1941.75	1,034
1942.1666666666667	1,041
1942.6666666666667	1,037
1943.1666666666667	1,036
1943.6666666666667	1,037
1944.0833333333333	1,040
1944.5833333333333	1,039
1945.0833333333333	1,042
1945.5833333333333	1,040
1946	1,035
1946.5	1,044
1947	1,037
1947.5	1,043
1947.9166666666667	1,042
1948.4166666666667	1,045
1948.9166666666667	1,037
1949.4166666666667	1,045
1949.8333333333333	1,036
1950.3333333333333	1,039
1950.8333333333333	1,042
1951.3333333333333	1,043
1951.8333333333333	1,035
1952.25	1,038
1952.75	1,034
1953.25	1,039
1953.75	1,035
1954.1666666666667	1,039
1954.6666666666667	1,040
1955.1666666666667	1,040
1955.6666666666667	1,038
1956.0833333333333	1,035
1956.5833333333333	1,041
1957.0833333333333	1,040
1957.5833333333333	1,040
1958	1,037
1958.5	1,041
1959	1,038
1959.5	1,044
1959.9166666666667	1,039
1960.4166666666667	1,045
1960.9166666666667	1,038
1961.4166666666667	1,044
1961.8333333333333	1,036
1962.3333333333333	1,043
1962.8333333333333	1,036
1963.3333333333333	1,045
1963.75	1,034
1964.25	1,035
1964.75	1,035
1965.25	1,037
1965.6666666666667	1,037
1966.1666666666667	1,035
1966.6666666666667	1,037
1967.1666666666667	1,035
1967.5833333333333	1,042
1968.0833333333333	1,041
1968.5833333333333	1,041
1969.0833333333333	1,035
1969.5	1,044
1970	1,036
1970.5	1,043
1971	1,035
1971.4166666666667	1,041
1971.9166666666667	1,035
1972.4166666666667	1,044
1972.9166666666667	1,035
1973.3333333333333	1,041
1973.8333333333333	1,035
1974.3333333333333	1,038
1974.8333333333333	1,034
1975.25	1,034
1975.75	1,036
1976.25	1,036
1976.75	1,036
1977.1666666666667	1,038
1977.6666666666667	1,039
1978.1666666666667	1,040
1978.6666666666667	1,041
1979.0833333333333	1,036
1979.5833333333333	1,039
1980.0833333333333	1,038
1980.5833333333333	1,041
1981	1,042
1981.5	1,042
1982	1,035
1982.5	1,044
1982.9166666666667	1,036
1983.4166666666667	1,044
1983.9166666666667	1,035
1984.4166666666667	1,044
1984.8333333333333	1,035
1985.3333333333333	1,043
1985.8333333333333	1,037
1986.3333333333333	1,041
1986.75	1,035
1987.25	1,043
1987.75	1,036
1988.25	1,042
1988.75	1,036
1989.1666666666667	1,037
1989.6666666666667	1,040
1990.1666666666667	1,038
1990.6666666666667	1,040
1991.0833333333333	1,042
1991.5833333333333	1,042
1992.0833333333333	1,037
1992.5833333333333	1,042
1993	1,035
1993.5	1,043
1994	1,035
1994.5	1,042
1994.9166666666667	1,038
1995.4166666666667	1,044
1995.9166666666667	1,042
1996.4166666666667	1,045
1996.8333333333333	1,036
1997.3333333333333	1,041
1997.8333333333333	1,041
1998.3333333333333	1,044
1998.75	1,036
1999.25	1,036
1999.75	1,037
2000.25	1,041
2000.6666666666667	1,041
2001.1666666666667	1,035
2001.6666666666667	1,037
2002.1666666666667	1,040
2002.5833333333333	1,043
2003.0833333333333	1,041
2003.5833333333333	1,041
2004.0833333333333	1,038
2004.5	1,043
2005	1,041
2005.5	1,043
2006	1,041
2006.4166666666667	1,044
2006.9166666666667	1,039
2007.4166666666667	1,044
2007.9166666666667	1,040
2008.3333333333333	1,040
2008.8333333333333	1,039
2009.3333333333333	1,041
2009.8333333333333	1,039
2010.25	1,038
2010.75	1,039
2011.25	1,040
2011.75	1,041
2012.1666666666667	1,040
2012.6666666666667	1,041
2013.1666666666667	1,038
2013.6666666666667	1,040
2014.0833333333333	1,040
2014.5833333333333	1,043
2015.0833333333333	1,044
2015.5833333333333	1,041
2016	1,041
2016.5	1,043
2017	1,039
2017.5	1,044
2017.9166666666667	1,040
2018.4166666666667	1,044
2018.9166666666667	1,036
2019.4166666666667	1,044
2019.8333333333333	1,036
2020.3333333333333	1,044
2020.8333333333333	1,038
2021.3333333333333	1,043
2021.75	1,038
2022.25	1,041
2022.75	1,037
2023.25	1,038
2023.6666666666667	1,038
2024.1666666666667	1,042
2024.6666666666667	1,038
2025.1666666666667	1,038
2025.5833333333333	1,041
2026.0833333333333	1,041
2026.5833333333333	1,041

Rate and persistence

-0.11 Mm³

Mean drawdown 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

Bumping Lake And Bumping 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	1912–2026
Completeness	99.7% 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	100% of the months between 1912 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-3647.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), Bumping Lake And Bumping Lake reservoir records, accessed 2026-09-02, hydrionis.com/reservoirs/reservoir-usbr-3647/

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 Bumping Lake And Bumping 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

1,376 monthly observations 1912–2026 Mm³

Spatially aggregatedHigh confidenceAugust 2026

Source: USBR — Reservoir operations and Colorado River data, RISE catalogue item 129605. 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.