Bumping Lake And Bumping Lake — storage

Storage now, against this reservoir's own record

14.73 Mm³

Stored, September 2026

42nd

Percentile among 115 Seps on record

-26.3%

Against the Sep 1991–2020 average

+3.0%

Change over the 12 months to 2026-09

Storage in September 2026 was around the middle of the Sep record, ranked against 115 other Seps held for this reservoir.

Storage, 1912–2026

Monthly mean storage

1,377 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 1,377 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,377 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
November 1928	10.6
April 1929	6.36
October 1929	5.57
April 1930	37.3
October 1930	3.38
March 1931	19.7
September 1931	3.59
March 1932	29.6
September 1932	15.3
February 1933	17.3
August 1933	38.9
February 1934	34.4
August 1934	9.29
January 1935	34.7
July 1935	42.7
January 1936	3.60
July 1936	41.5
December 1936	4.63
June 1937	44.2
December 1937	19.2
June 1938	43.8
November 1938	5.68
May 1939	38.1
November 1939	3.27
May 1940	43.4
October 1940	3.23
April 1941	31.4
October 1941	3.50
April 1942	35.9
September 1942	11.0
March 1943	7.61
September 1943	13.0
March 1944	25.6
August 1944	17.8
February 1945	31.9
August 1945	22.9
February 1946	3.90
August 1946	25.6
January 1947	10.8
July 1947	34.9
January 1948	27.1
July 1948	42.5
December 1948	12.6
June 1949	44.3
December 1949	18.7
June 1950	39.5
November 1950	31.4
May 1951	33.6
November 1951	4.22
May 1952	39.5
October 1952	3.71
April 1953	16.9
October 1953	5.49
April 1954	17.7
September 1954	20.6
March 1955	22.0
September 1955	14.2
March 1956	3.94
August 1956	27.2
February 1957	20.8
August 1957	20.6
February 1958	16.3
July 1958	25.7
January 1959	13.8
July 1959	39.8
January 1960	8.11
June 1960	43.6
December 1960	13.1
June 1961	41.0
December 1961	8.43
June 1962	44.5
November 1962	7.17
May 1963	43.3
November 1963	4.26
May 1964	11.9
October 1964	6.20
April 1965	11.4
October 1965	5.84
April 1966	12.1
September 1966	10.1
March 1967	4.89
September 1967	16.0
March 1968	26.4
August 1968	25.4
February 1969	4.03
August 1969	30.4
February 1970	10.1
July 1970	37.7
January 1971	4.73
July 1971	43.2
January 1972	5.57
June 1972	42.6
December 1972	6.54
June 1973	31.6
December 1973	7.27
May 1974	14.8
November 1974	3.60
May 1975	11.5
November 1975	11.0
April 1976	8.09
October 1976	9.17
April 1977	22.8
October 1977	8.89
April 1978	36.7
September 1978	27.2
March 1979	13.6
September 1979	4.93
March 1980	29.0
August 1980	24.0
February 1981	28.3
August 1981	27.7
February 1982	11.6
July 1982	40.5
January 1983	8.88
July 1983	39.9
January 1984	17.1
June 1984	39.1
December 1984	4.73
June 1985	39.5
December 1985	7.11
May 1986	26.2
November 1986	8.14
May 1987	40.9
November 1987	4.54
April 1988	32.4
October 1988	8.24
April 1989	21.3
October 1989	9.49
March 1990	13.2
September 1990	20.0
March 1991	25.6
September 1991	14.7
February 1992	12.6
August 1992	28.7
February 1993	6.81
August 1993	25.2
February 1994	7.60
July 1994	30.1
January 1995	18.0
July 1995	33.0
January 1996	19.8
June 1996	43.4
December 1996	10.5
June 1997	43.2
December 1997	14.4
May 1998	41.9
November 1998	12.6
May 1999	18.3
November 1999	18.8
April 2000	26.0
October 2000	16.3
April 2001	8.64
October 2001	6.17
March 2002	20.7
September 2002	23.1
March 2003	30.9
September 2003	17.7
February 2004	14.0
August 2004	28.7
February 2005	34.3
August 2005	26.0
January 2006	25.5
July 2006	40.3
January 2007	22.2
July 2007	40.4
December 2007	22.1
June 2008	38.1
December 2008	14.6
June 2009	42.0
November 2009	17.9
May 2010	25.5
November 2010	20.9
May 2011	22.9
November 2011	21.8
April 2012	15.3
October 2012	19.5
April 2013	23.6
October 2013	24.5
March 2014	27.1
September 2014	21.5
March 2015	41.9
September 2015	20.7
February 2016	25.5
August 2016	29.1
February 2017	20.3
August 2017	30.0
January 2018	21.0
July 2018	37.5
January 2019	11.7
July 2019	39.7
December 2019	7.99
June 2020	41.3
December 2020	17.2
June 2021	41.7
November 2021	21.4
May 2022	29.1
November 2022	11.9
May 2023	36.4
October 2023	7.59
April 2024	35.0
October 2024	6.55
April 2025	33.4
September 2025	14.3
March 2026	34.5
September 2026	14.7

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	24.7
Sep	20.0	14.7
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

1,377 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 1,377 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,377 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
1928.8333333333333	1,037
1929.25	1,035
1929.75	1,035
1930.25	1,043
1930.75	1,034
1931.1666666666667	1,039
1931.6666666666667	1,034
1932.1666666666667	1,042
1932.6666666666667	1,038
1933.0833333333333	1,039
1933.5833333333333	1,044
1934.0833333333333	1,043
1934.5833333333333	1,036
1935	1,043
1935.5	1,044
1936	1,034
1936.5	1,044
1936.9166666666667	1,035
1937.4166666666667	1,045
1937.9166666666667	1,039
1938.4166666666667	1,045
1938.8333333333333	1,035
1939.3333333333333	1,044
1939.8333333333333	1,034
1940.3333333333333	1,045
1940.75	1,034
1941.25	1,042
1941.75	1,034
1942.25	1,043
1942.6666666666667	1,037
1943.1666666666667	1,036
1943.6666666666667	1,037
1944.1666666666667	1,041
1944.5833333333333	1,039
1945.0833333333333	1,042
1945.5833333333333	1,040
1946.0833333333333	1,034
1946.5833333333333	1,041
1947	1,037
1947.5	1,043
1948	1,041
1948.5	1,044
1948.9166666666667	1,037
1949.4166666666667	1,045
1949.9166666666667	1,039
1950.4166666666667	1,044
1950.8333333333333	1,042
1951.3333333333333	1,043
1951.8333333333333	1,035
1952.3333333333333	1,044
1952.75	1,034
1953.25	1,039
1953.75	1,035
1954.25	1,039
1954.6666666666667	1,040
1955.1666666666667	1,040
1955.6666666666667	1,038
1956.1666666666667	1,034
1956.5833333333333	1,041
1957.0833333333333	1,040
1957.5833333333333	1,040
1958.0833333333333	1,039
1958.5	1,041
1959	1,038
1959.5	1,044
1960	1,036
1960.4166666666667	1,045
1960.9166666666667	1,038
1961.4166666666667	1,044
1961.9166666666667	1,036
1962.4166666666667	1,045
1962.8333333333333	1,036
1963.3333333333333	1,045
1963.8333333333333	1,035
1964.3333333333333	1,037
1964.75	1,035
1965.25	1,037
1965.75	1,035
1966.25	1,037
1966.6666666666667	1,037
1967.1666666666667	1,035
1967.6666666666667	1,038
1968.1666666666667	1,041
1968.5833333333333	1,041
1969.0833333333333	1,035
1969.5833333333333	1,042
1970.0833333333333	1,037
1970.5	1,043
1971	1,035
1971.5	1,045
1972	1,035
1972.4166666666667	1,044
1972.9166666666667	1,035
1973.4166666666667	1,042
1973.9166666666667	1,036
1974.3333333333333	1,038
1974.8333333333333	1,034
1975.3333333333333	1,037
1975.8333333333333	1,037
1976.25	1,036
1976.75	1,036
1977.25	1,040
1977.75	1,036
1978.25	1,043
1978.6666666666667	1,041
1979.1666666666667	1,038
1979.6666666666667	1,035
1980.1666666666667	1,042
1980.5833333333333	1,041
1981.0833333333333	1,041
1981.5833333333333	1,041
1982.0833333333333	1,037
1982.5	1,044
1983	1,036
1983.5	1,044
1984	1,039
1984.4166666666667	1,044
1984.9166666666667	1,035
1985.4166666666667	1,044
1985.9166666666667	1,036
1986.3333333333333	1,041
1986.8333333333333	1,036
1987.3333333333333	1,044
1987.8333333333333	1,035
1988.25	1,042
1988.75	1,036
1989.25	1,040
1989.75	1,036
1990.1666666666667	1,038
1990.6666666666667	1,040
1991.1666666666667	1,041
1991.6666666666667	1,038
1992.0833333333333	1,037
1992.5833333333333	1,042
1993.0833333333333	1,036
1993.5833333333333	1,041
1994.0833333333333	1,036
1994.5	1,042
1995	1,039
1995.5	1,043
1996	1,040
1996.4166666666667	1,045
1996.9166666666667	1,037
1997.4166666666667	1,045
1997.9166666666667	1,038
1998.3333333333333	1,044
1998.8333333333333	1,037
1999.3333333333333	1,039
1999.8333333333333	1,039
2000.25	1,041
2000.75	1,039
2001.25	1,036
2001.75	1,035
2002.1666666666667	1,040
2002.6666666666667	1,040
2003.1666666666667	1,042
2003.6666666666667	1,039
2004.0833333333333	1,038
2004.5833333333333	1,042
2005.0833333333333	1,043
2005.5833333333333	1,041
2006	1,041
2006.5	1,044
2007	1,040
2007.5	1,044
2007.9166666666667	1,040
2008.4166666666667	1,044
2008.9166666666667	1,038
2009.4166666666667	1,044
2009.8333333333333	1,039
2010.3333333333333	1,041
2010.8333333333333	1,040
2011.3333333333333	1,040
2011.8333333333333	1,040
2012.25	1,038
2012.75	1,039
2013.25	1,040
2013.75	1,041
2014.1666666666667	1,041
2014.6666666666667	1,040
2015.1666666666667	1,044
2015.6666666666667	1,040
2016.0833333333333	1,041
2016.5833333333333	1,042
2017.0833333333333	1,040
2017.5833333333333	1,042
2018	1,040
2018.5	1,043
2019	1,037
2019.5	1,044
2019.9166666666667	1,036
2020.4166666666667	1,044
2020.9166666666667	1,039
2021.4166666666667	1,044
2021.8333333333333	1,040
2022.3333333333333	1,042
2022.8333333333333	1,037
2023.3333333333333	1,043
2023.75	1,036
2024.25	1,043
2024.75	1,035
2025.25	1,043
2025.6666666666667	1,038
2026.1666666666667	1,043
2026.6666666666667	1,038

Rate and persistence

+0.04 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

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	99.8% 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	2026-10-01
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-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 2026-10-05, 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

1,377 monthly observations 1912–2026 Mm³

Spatially aggregatedHigh confidenceSeptember 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 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.