Deadwood Reservoir — storage

Storage now, against this reservoir's own record

119.73 Mm³

Stored, August 2026

28th

Percentile among 96 Augs on record

-8.7%

Against the Aug 1991–2020 average

-0.3%

Change over the 12 months to 2026-08

Storage in August 2026 was lower than most Augs on record, ranked against 96 other Augs held for this reservoir.

Storage, 1931–2026

Monthly mean storage

1,148 monthly values, 1931 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 1,148 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,148 would be longer than this page and unusable with a screen reader.
Period	Deadwood Reservoir (Mm³)
January 1931	3.47
June 1931	63.3
November 1931	4.92
March 1932	21.5
August 1932	170
January 1933	56.1
June 1933	169
November 1933	55.1
March 1934	78.7
August 1934	102
January 1935	21.8
June 1935	136
November 1935	23.5
March 1936	33.9
August 1936	162
January 1937	60.5
June 1937	145
November 1937	50.8
March 1938	73.5
August 1938	195
January 1939	107
June 1939	201
November 1939	69.0
March 1940	89.8
August 1940	159
January 1941	113
June 1941	205
November 1941	149
March 1942	184
August 1942	184
January 1943	122
June 1943	208
November 1943	108
March 1944	129
August 1944	159
January 1945	73.0
June 1945	187
November 1945	103
March 1946	130
August 1946	178
January 1947	128
June 1947	206
November 1947	75.4
March 1948	100
August 1948	199
January 1949	100
June 1949	190
November 1949	108
March 1950	128
August 1950	201
January 1951	120
June 1951	198
November 1951	10.7
March 1952	36.3
August 1952	194
January 1953	69.8
June 1953	192
November 1953	82.3
March 1954	108
August 1954	173
January 1955	76.8
June 1955	168
November 1955	61.5
March 1956	99.7
August 1956	185
January 1957	75.0
June 1957	204
November 1957	39.4
March 1958	59.3
August 1958	172
January 1959	71.4
June 1959	191
November 1959	75.6
March 1960	99.6
August 1960	162
January 1961	54.7
June 1961	160
November 1961	53.8
March 1962	73.7
August 1962	184
January 1963	101
June 1963	207
November 1963	88.7
March 1964	112
August 1964	128
January 1965	109
June 1965	198
November 1965	111
March 1966	134
August 1966	138
January 1967	65.8
June 1967	183
November 1967	84.3
March 1968	109
August 1968	97.6
January 1969	88.8
June 1969	199
November 1969	82.2
March 1970	107
August 1970	153
January 1971	110
June 1971	186
November 1971	82.7
March 1972	110
August 1972	182
January 1973	108
June 1973	174
November 1973	12.6
March 1974	56.9
August 1974	165
January 1975	99.0
June 1975	148
November 1975	91.8
March 1976	123
August 1976	135
January 1977	99.5
June 1977	105
November 1977	42.2
March 1978	67.1
August 1978	159
January 1979	95.2
June 1979	184
October 1979	49.8
March 1980	76.8
August 1980	127
January 1981	130
June 1981	206
October 1981	81.5
March 1982	119
August 1982	149
January 1983	118
June 1983	208
October 1983	90.0
March 1984	134
August 1984	125
January 1985	130
June 1985	200
October 1985	79.7
March 1986	124
August 1986	93.9
January 1987	106
June 1987	164
October 1987	65.0
March 1988	86.2
August 1988	63.6
January 1989	70.1
June 1989	192
October 1989	89.7
March 1990	114
August 1990	121
January 1991	99.7
June 1991	171
October 1991	73.3
March 1992	72.3
August 1992	64.3
January 1993	63.5
June 1993	202
October 1993	122
March 1994	126
August 1994	77.8
January 1995	66.5
June 1995	202
October 1995	156
March 1996	152
August 1996	175
January 1997	165
June 1997	202
October 1997	150
March 1998	160
August 1998	166
January 1999	154
June 1999	188
October 1999	136
March 2000	148
August 2000	150
January 2001	114
June 2001	146
October 2001	62.7
March 2002	66.6
August 2002	104
January 2003	69.5
June 2003	191
October 2003	98.1
March 2004	104
August 2004	126
January 2005	90.8
June 2005	178
October 2005	82.1
March 2006	94.6
August 2006	151
January 2007	125
June 2007	201
October 2007	68.5
March 2008	83.1
August 2008	125
January 2009	99.3
June 2009	189
October 2009	109
March 2010	116
August 2010	122
January 2011	123
June 2011	177
October 2011	111
March 2012	123
August 2012	137
January 2013	118
June 2013	185
October 2013	80.7
March 2014	112
August 2014	138
January 2015	138
June 2015	190
October 2015	84.2
March 2016	94.1
August 2016	128
January 2017	116
June 2017	182
October 2017	142
March 2018	140
August 2018	133
January 2019	106
June 2019	188
October 2019	108
March 2020	113
August 2020	125
January 2021	98.3
June 2021	168
October 2021	70.0
March 2022	80.7
August 2022	128
January 2023	95.7
June 2023	184
October 2023	112
March 2024	124
August 2024	105
January 2025	95.6
June 2025	186
October 2025	92.7
March 2026	141
August 2026	120

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	123
Feb	111	131
Mar	112	141
Apr	119	170
May	152	184
Jun	186	187
Jul	174	177
Aug	131	120
Sep	103	87.9
Oct	104	92.7
Nov	106	99.5
Dec	109	109

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

752 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 752 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 752 would be longer than this page and unusable with a screen reader.
Period	Deadwood Reservoir (m)
1960.9166666666667	1,610
1961.1666666666667	1,613
1961.4166666666667	1,622
1961.6666666666667	1,609
1962	1,612
1962.25	1,615
1962.5	1,625
1962.75	1,613
1963	1,617
1963.25	1,621
1963.5	1,625
1963.8333333333333	1,616
1964.0833333333333	1,618
1964.3333333333333	1,621
1964.5833333333333	1,620
1964.8333333333333	1,615
1965.0833333333333	1,619
1965.3333333333333	1,619
1965.6666666666667	1,617
1965.9166666666667	1,618
1966.1666666666667	1,620
1966.4166666666667	1,626
1966.6666666666667	1,616
1966.9166666666667	1,612
1967.1666666666667	1,614
1967.5	1,626
1967.75	1,614
1968	1,616
1968.25	1,619
1968.5	1,623
1968.75	1,613
1969	1,616
1969.3333333333333	1,621
1969.5833333333333	1,618
1969.8333333333333	1,615
1970.0833333333333	1,617
1970.3333333333333	1,621
1970.5833333333333	1,622
1970.8333333333333	1,616
1971.1666666666667	1,619
1971.4166666666667	1,625
1971.6666666666667	1,618
1971.9166666666667	1,616
1972.1666666666667	1,618
1972.4166666666667	1,624
1972.6666666666667	1,618
1973	1,618
1973.25	1,619
1973.5	1,619
1973.75	1,595
1974	1,607
1974.25	1,614
1974.5	1,626
1974.8333333333333	1,615
1975.0833333333333	1,617
1975.3333333333333	1,618
1975.5833333333333	1,623
1975.8333333333333	1,616
1976.0833333333333	1,618
1976.3333333333333	1,623
1976.6666666666667	1,615
1976.9166666666667	1,616
1977.1666666666667	1,617
1977.4166666666667	1,617
1977.6666666666667	1,608
1980.9166666666667	1,619
1981.1666666666667	1,621
1981.5	1,624
1981.75	1,615
1982	1,617
1982.25	1,620
1982.5	1,626
1982.75	1,616
1983	1,619
1983.3333333333333	1,624
1983.5833333333333	1,623
1983.8333333333333	1,617
1984.0833333333333	1,619
1984.3333333333333	1,624
1984.5833333333333	1,619
1984.8333333333333	1,618
1985.1666666666667	1,621
1985.4166666666667	1,626
1985.6666666666667	1,614
1985.9166666666667	1,616
1986.1666666666667	1,619
1986.4166666666667	1,626
1986.6666666666667	1,615
1987	1,617
1987.25	1,620
1987.5	1,616
1987.75	1,613
1988	1,614
1988.25	1,617
1988.5	1,618
1988.8333333333333	1,612
1989.0833333333333	1,614
1989.3333333333333	1,621
1989.5833333333333	1,618
1989.8333333333333	1,616
1990.0833333333333	1,618
1990.3333333333333	1,623
1990.6666666666667	1,615
1990.9166666666667	1,616
1991.1666666666667	1,618
1991.4166666666667	1,623
1991.6666666666667	1,614
1991.9166666666667	1,614
1992.1666666666667	1,614
1992.5	1,616
1992.75	1,610
1993	1,612
1993.25	1,615
1993.5	1,625
1993.75	1,619
1994	1,619
1994.3333333333333	1,622
1994.5833333333333	1,614
1994.8333333333333	1,612
1995.0833333333333	1,613
1995.3333333333333	1,620
1995.5833333333333	1,624
1995.8333333333333	1,622
1996.0833333333333	1,622
1996.4166666666667	1,627
1996.6666666666667	1,622
1996.9166666666667	1,623
1997.1666666666667	1,616
1997.4166666666667	1,626
1997.6666666666667	1,621
1997.9166666666667	1,622
1998.25	1,622
1998.5	1,626
1998.75	1,621
1999	1,622
1999.25	1,617
1999.5	1,626
1999.75	1,620
2000.0833333333333	1,621
2000.3333333333333	1,625
2000.5833333333333	1,622
2000.8333333333333	1,618
2001.0833333333333	1,618
2001.3333333333333	1,620
2001.5833333333333	1,614
2001.9166666666667	1,613
2002.1666666666667	1,613
2002.4166666666667	1,622
2002.6666666666667	1,613
2002.9166666666667	1,613
2003.1666666666667	1,614
2003.4166666666667	1,625
2003.75	1,617
2004	1,617
2004.25	1,619
2004.5	1,625
2004.75	1,615
2005	1,616
2005.25	1,617
2005.5833333333333	1,619
2005.8333333333333	1,615
2006.0833333333333	1,616
2006.3333333333333	1,623
2006.5833333333333	1,622
2006.8333333333333	1,619
2007.0833333333333	1,619
2007.4166666666667	1,626
2007.6666666666667	1,613
2007.9166666666667	1,615
2008.1666666666667	1,616
2008.4166666666667	1,626
2008.6666666666667	1,617
2008.9166666666667	1,617
2009.25	1,618
2009.5	1,625
2009.75	1,619
2010	1,619
2010.25	1,620
2010.5	1,624
2010.75	1,619
2011.0833333333333	1,620
2011.3333333333333	1,622
2011.5833333333333	1,623
2011.8333333333333	1,619
2012.0833333333333	1,620
2012.3333333333333	1,624
2012.5833333333333	1,621
2012.9166666666667	1,619
2013.1666666666667	1,620
2013.4166666666667	1,625
2013.6666666666667	1,614
2013.9166666666667	1,617
2014.1666666666667	1,619
2014.4166666666667	1,626
2014.75	1,619
2015	1,621
2015.25	1,625
2015.5	1,623
2015.75	1,616
2016	1,616
2016.25	1,619
2016.5833333333333	1,620
2016.8333333333333	1,619
2017.0833333333333	1,620
2017.3333333333333	1,624
2017.5833333333333	1,624
2017.9166666666667	1,623
2018.1666666666667	1,622
2018.5	1,625
2018.75	1,618
2019	1,618
2019.25	1,620
2019.5	1,625
2019.75	1,618
2020	1,619
2020.3333333333333	1,623
2020.5833333333333	1,620
2020.8333333333333	1,617
2021.0833333333333	1,618
2021.3333333333333	1,622
2021.5833333333333	1,616
2021.8333333333333	1,614
2022.1666666666667	1,615
2022.4166666666667	1,625
2022.6666666666667	1,616
2022.9166666666667	1,617
2023.1666666666667	1,617
2023.4166666666667	1,625
2023.6666666666667	1,618
2024	1,620
2024.25	1,621
2024.5	1,624
2024.75	1,615
2025	1,617
2025.25	1,619
2025.5	1,624
2025.8333333333333	1,617
2026.0833333333333	1,621
2026.3333333333333	1,625
2026.5833333333333	1,620

Rate and persistence

-0.03 Mm³

Mean drawdown 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

Deadwood 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	1931–2026
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 1931 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-3649.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), Deadwood Reservoir reservoir records, accessed 2026-09-02, hydrionis.com/reservoirs/reservoir-usbr-3649/

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 Deadwood 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

1,148 monthly observations 1931–2026 Mm³

Spatially aggregatedHigh confidenceAugust 2026

Source: USBR — Reservoir operations and Colorado River data, RISE catalogue item 130055. 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.