Ochoco Reservoir — storage

Storage now, against this reservoir's own record

14.94 Mm³

Stored, August 2026

21st

Percentile among 43 Augs on record

-41.9%

Against the Aug 1991–2020 average

-59.2%

Change over the 12 months to 2026-08

Storage in August 2026 was lower than most Augs on record, ranked against 43 other Augs held for this reservoir.

Storage, 1969–2026

Monthly mean storage

518 monthly values, 1969 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 518 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 518 would be longer than this page and unusable with a screen reader.
Period	Ochoco Reservoir (Mm³)
November 1969	21.4
November 1974	24.9
November 1983	30.0
January 1984	36.2
April 1984	56.4
June 1984	57.2
August 1984	39.9
October 1984	28.3
December 1984	33.1
February 1985	32.1
May 1985	52.8
July 1985	39.5
September 1985	25.1
November 1985	22.3
January 1986	25.0
March 1986	56.7
June 1986	48.8
August 1986	29.9
October 1986	22.3
December 1986	24.6
February 1987	31.8
April 1987	55.3
July 1987	40.0
September 1987	25.9
November 1987	21.4
January 1988	23.7
March 1988	30.9
May 1988	31.7
August 1988	15.1
October 1988	1.28
December 1988	2.34
February 1989	7.36
April 1989	47.2
June 1989	48.8
September 1989	20.2
November 1989	10.5
January 1990	12.0
March 1990	16.0
May 1990	18.1
July 1990	12.7
October 1990	0.638
December 1990	0.923
February 1991	3.07
April 1991	6.89
June 1991	13.4
August 1991	6.75
November 1991	1.08
January 1992	6.16
March 1992	10.5
May 1992	13.4
July 1992	8.07
September 1992	1.30
November 1992	0.521
February 1993	3.75
April 1993	31.4
June 1993	30.9
August 1993	19.8
October 1993	12.2
December 1993	10.6
March 1994	0.286
May 1994	13.4
July 1994	8.07
September 1994	1.30
November 1994	0.521
January 1995	1.68
April 1995	30.8
June 1995	30.6
August 1995	15.0
October 1995	0.409
December 1995	5.45
February 1996	26.8
May 1996	53.3
July 1996	41.3
September 1996	25.6
November 1996	21.8
January 1997	49.5
March 1997	50.3
June 1997	52.1
August 1997	37.9
October 1997	30.0
December 1997	30.2
February 1998	35.8
April 1998	49.3
July 1998	49.4
September 1998	33.1
November 1998	27.7
January 1999	32.8
March 1999	32.9
May 1999	40.0
August 1999	25.4
October 1999	15.0
December 1999	15.0
February 2000	20.7
April 2000	48.0
June 2000	45.5
September 2000	24.2
November 2000	20.4
January 2001	21.1
March 2001	22.9
May 2001	27.7
July 2001	18.3
September 2001	11.5
December 2001	9.48
February 2002	17.6
April 2002	32.0
June 2002	30.6
August 2002	18.3
October 2002	12.6
January 2003	13.5
March 2003	26.0
May 2003	39.6
July 2003	29.9
September 2003	19.1
November 2003	15.7
February 2004	28.4
April 2004	53.1
June 2004	51.7
August 2004	38.6
October 2004	31.6
December 2004	31.0
March 2005	35.3
May 2005	47.5
July 2005	43.6
September 2005	29.7
November 2005	27.0
January 2006	35.6
April 2006	45.8
June 2006	51.8
August 2006	36.6
October 2006	27.6
December 2006	30.0
February 2007	37.2
May 2007	50.3
July 2007	36.5
September 2007	24.4
November 2007	21.9
January 2008	23.6
March 2008	33.9
June 2008	51.7
August 2008	36.3
October 2008	27.1
December 2008	26.7
February 2009	29.1
April 2009	37.6
June 2009	40.8
September 2009	22.4
November 2009	19.3
January 2010	21.0
March 2010	31.6
May 2010	51.9
July 2010	47.3
October 2010	29.2
December 2010	32.5
February 2011	41.8
April 2011	47.9
June 2011	52.6
August 2011	41.2
November 2011	30.4
January 2012	31.5
March 2012	40.1
May 2012	51.7
July 2012	41.6
September 2012	25.1
December 2012	22.2
February 2013	27.1
April 2013	40.0
June 2013	31.7
August 2013	17.3
October 2013	12.2
January 2014	12.5
March 2014	29.5
May 2014	42.4
July 2014	31.2
September 2014	20.0
November 2014	18.3
February 2015	35.3
April 2015	42.2
June 2015	34.4
August 2015	18.7
October 2015	12.5
December 2015	12.6
March 2016	46.6
May 2016	50.7
July 2016	40.9
September 2016	26.9
November 2016	23.8
January 2017	25.3
April 2017	51.2
June 2017	49.5
August 2017	32.3
October 2017	23.8
December 2017	23.7
February 2018	26.3
April 2018	35.1
July 2018	21.7
September 2018	9.45
November 2018	6.78
January 2019	7.31
March 2019	11.6
May 2019	46.6
August 2019	31.5
October 2019	25.0
December 2019	24.6
February 2020	26.7
April 2020	29.1
June 2020	25.6
September 2020	9.10
November 2020	7.30
January 2021	7.43
March 2021	10.8
May 2021	13.1
July 2021	7.36
October 2021	4.19
December 2021	4.24
February 2022	4.84
April 2022	9.22
June 2022	11.9
August 2022	7.19
November 2022	5.33
January 2023	5.75
March 2023	7.34
May 2023	34.1
July 2023	31.3
September 2023	19.1
December 2023	17.6
February 2024	36.6
April 2024	50.8
June 2024	50.6
August 2024	35.6
October 2024	28.2
January 2025	31.3
March 2025	38.3
May 2025	53.4
July 2025	43.5
September 2025	32.5
November 2025	29.9
February 2026	32.3
April 2026	33.9
June 2026	25.5
August 2026	14.9

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	20.8	31.2
Feb	24.3	32.3
Mar	31.1	34.9
Apr	38.4	33.9
May	41.3	30.0
Jun	39.2	25.5
Jul	32.9	20.1
Aug	25.7	14.9
Sep	20.6	32.5
Oct	17.9	30.4
Nov	17.6	29.9
Dec	18.7	29.9

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

505 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 505 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 505 would be longer than this page and unusable with a screen reader.
Period	Ochoco Reservoir (m)
1983.75	947
1983.9166666666667	948
1984.0833333333333	950
1984.25	954
1984.4166666666667	954
1984.6666666666667	947
1984.8333333333333	947
1985	948
1985.1666666666667	947
1985.3333333333333	953
1985.5	950
1985.6666666666667	945
1985.8333333333333	944
1986	945
1986.25	954
1986.4166666666667	952
1986.5833333333333	947
1986.75	944
1986.9166666666667	945
1987.0833333333333	947
1987.25	954
1987.4166666666667	952
1987.5833333333333	948
1987.8333333333333	944
1988	945
1988.1666666666667	947
1988.3333333333333	947
1988.5	943
1988.6666666666667	937
1988.8333333333333	930
1989	935
1989.1666666666667	944
1989.3333333333333	953
1989.5833333333333	946
1989.75	940
1989.9166666666667	939
1990.0833333333333	940
1990.25	943
1990.4166666666667	942
1990.5833333333333	936
1990.75	930
1990.9166666666667	930
1991.1666666666667	935
1991.3333333333333	939
1991.5	939
1991.6666666666667	932
1991.8333333333333	931
1992	936
1992.1666666666667	939
1992.3333333333333	940
1992.5	937
1992.75	930
1992.9166666666667	930
1993.0833333333333	934
1993.25	948
1993.4166666666667	948
1993.5833333333333	944
1993.75	941
1993.9166666666667	940
1994.0833333333333	930
1995.1666666666667	945
1995.3333333333333	949
1995.5	945
1995.6666666666667	937
1995.8333333333333	931
1996	938
1996.1666666666667	952
1996.3333333333333	954
1996.5	951
1996.75	945
1996.9166666666667	948
1997.0833333333333	952
1997.25	954
1997.4166666666667	954
1997.5833333333333	950
1997.75	948
1997.9166666666667	948
1998.0833333333333	949
1998.25	953
1998.5	953
1998.6666666666667	949
1998.8333333333333	947
1999	948
1999.1666666666667	948
1999.3333333333333	951
1999.5	949
1999.6666666666667	944
1999.8333333333333	942
2000.0833333333333	944
2000.25	953
2000.4166666666667	952
2000.5833333333333	947
2000.75	944
2000.9166666666667	944
2001.0833333333333	945
2001.25	946
2001.4166666666667	945
2001.6666666666667	940
2001.8333333333333	939
2002	941
2002.1666666666667	945
2002.3333333333333	949
2002.5	945
2002.6666666666667	942
2002.8333333333333	941
2003	941
2003.25	949
2003.4166666666667	950
2003.5833333333333	945
2003.75	943
2003.9166666666667	943
2004.0833333333333	947
2004.25	954
2004.4166666666667	954
2004.5833333333333	950
2004.8333333333333	948
2005	948
2005.1666666666667	949
2005.3333333333333	953
2005.5	951
2005.6666666666667	948
2005.8333333333333	947
2006	949
2006.1666666666667	951
2006.3333333333333	954
2006.5833333333333	950
2006.75	947
2006.9166666666667	948
2007.0833333333333	950
2007.25	954
2007.4166666666667	952
2007.5833333333333	947
2007.75	945
2007.9166666666667	945
2008.1666666666667	949
2008.3333333333333	953
2008.5	952
2008.6666666666667	948
2008.8333333333333	946
2009	947
2009.1666666666667	948
2009.3333333333333	951
2009.5	949
2009.75	944
2009.9166666666667	944
2010.0833333333333	946
2010.25	951
2010.4166666666667	954
2010.5833333333333	950
2010.75	947
2010.9166666666667	948
2011.0833333333333	951
2011.3333333333333	953
2011.5	953
2011.6666666666667	949
2011.8333333333333	948
2012	948
2012.1666666666667	951
2012.3333333333333	954
2012.5	951
2012.6666666666667	946
2012.9166666666667	945
2013.0833333333333	947
2013.25	951
2013.4166666666667	948
2013.5833333333333	943
2013.75	941
2013.9166666666667	941
2014.0833333333333	942
2014.25	951
2014.4166666666667	950
2014.6666666666667	944
2014.8333333333333	943
2015	947
2015.1666666666667	950
2015.3333333333333	950
2015.5	946
2015.6666666666667	942
2015.8333333333333	941
2016	942
2016.25	954
2016.4166666666667	952
2016.5833333333333	949
2016.75	946
2016.9166666666667	946
2017.0833333333333	948
2017.25	953
2017.4166666666667	953
2017.5833333333333	948
2017.8333333333333	945
2018	946
2018.1666666666667	947
2018.3333333333333	949
2018.5	945
2018.6666666666667	939
2018.8333333333333	937
2019	938
2019.1666666666667	940
2019.4166666666667	952
2019.5833333333333	948
2019.75	946
2019.9166666666667	946
2020.0833333333333	947
2020.25	947
2020.4166666666667	946
2020.5833333333333	941
2020.75	938
2021	938
2021.1666666666667	940
2021.3333333333333	941
2021.5	938
2021.6666666666667	935
2021.8333333333333	935
2022	936
2022.1666666666667	937
2022.3333333333333	940
2022.5	940
2022.75	936
2022.9166666666667	936
2023.0833333333333	937
2023.25	942
2023.4166666666667	950
2023.5833333333333	946
2023.75	943
2023.9166666666667	943
2024.0833333333333	950
2024.3333333333333	954
2024.5	951
2024.6666666666667	948
2024.8333333333333	947
2025	948
2025.1666666666667	950
2025.3333333333333	954
2025.5	951
2025.6666666666667	948
2025.9166666666667	948
2026.0833333333333	948
2026.25	949
2026.4166666666667	946
2026.5833333333333	942

Rate and persistence

-1.81 Mm³

Mean drawdown per month over 12 months

2 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

Ochoco 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	1969–2026
Completeness	74.4% 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	74% of the months between 1969 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-3665.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), Ochoco Reservoir reservoir records, accessed 2026-09-02, hydrionis.com/reservoirs/reservoir-usbr-3665/

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 Ochoco 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

518 monthly observations 1969–2026 Mm³

Spatially aggregatedHigh confidenceAugust 2026

Source: USBR — Reservoir operations and Colorado River data, RISE catalogue item 132075. 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.