Deerfield Reservoir — storage

Storage now, against this reservoir's own record

17.63 Mm³

Stored, August 2026

32nd

Percentile among 74 Augs on record

-2.8%

Against the Aug 1991–2020 average

-3.2%

Change over the 12 months to 2026-08

Storage in August 2026 was around the middle of the Aug record, ranked against 74 other Augs held for this reservoir.

Storage, 1952–2026

Monthly mean storage

887 monthly values, 1952 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 887 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 887 would be longer than this page and unusable with a screen reader.
Period	Deerfield Reservoir (Mm³)
October 1952	0
February 1953	0
May 1953	19.3
September 1953	18.0
January 1954	18.4
May 1954	19.1
August 1954	13.8
December 1954	12.8
April 1955	14.9
July 1955	14.6
November 1955	11.7
March 1956	13.3
June 1956	14.9
October 1956	9.92
February 1957	10.7
June 1957	13.4
September 1957	13.2
January 1958	14.2
May 1958	15.9
August 1958	13.5
December 1958	10.9
April 1959	12.5
August 1959	6.77
November 1959	1.35
March 1960	2.52
July 1960	4.30
October 1960	3.71
February 1961	3.72
June 1961	4.85
October 1961	4.53
January 1962	4.97
May 1962	6.65
September 1962	8.70
December 1962	9.26
April 1963	11.4
August 1963	16.7
November 1963	17.2
March 1964	18.6
July 1964	19.3
November 1964	16.7
February 1965	18.4
June 1965	19.2
October 1965	17.1
January 1966	18.5
May 1966	19.2
September 1966	17.2
January 1967	17.8
April 1967	19.3
August 1967	18.6
December 1967	17.7
March 1968	19.4
July 1968	19.2
November 1968	17.1
February 1969	18.6
June 1969	19.2
October 1969	16.0
February 1970	18.1
May 1970	19.3
September 1970	16.6
January 1971	18.0
April 1971	19.4
August 1971	19.3
December 1971	16.8
April 1972	18.8
July 1972	19.1
November 1972	16.1
March 1973	18.4
June 1973	19.2
October 1973	16.2
February 1974	18.1
May 1974	19.0
September 1974	17.7
January 1975	18.4
May 1975	19.0
August 1975	18.5
December 1975	18.0
April 1976	19.3
July 1976	19.1
November 1976	17.2
March 1977	19.1
July 1977	18.8
October 1977	17.6
February 1978	19.4
June 1978	19.3
September 1978	18.2
January 1979	18.9
May 1979	19.3
September 1979	18.2
December 1979	17.3
April 1980	19.3
August 1980	18.8
November 1980	17.3
March 1981	19.2
July 1981	19.1
October 1981	16.8
February 1982	18.3
June 1982	14.1
October 1982	1.36
January 1983	3.99
May 1983	5.48
September 1983	8.76
December 1983	10.9
April 1984	14.2
August 1984	16.9
December 1984	18.2
March 1985	19.6
July 1985	18.8
November 1985	16.8
February 1986	18.3
June 1986	18.8
October 1986	17.7
January 1987	17.4
May 1987	19.1
September 1987	17.4
January 1988	17.4
April 1988	19.0
August 1988	17.5
December 1988	17.2
March 1989	18.8
July 1989	18.0
November 1989	16.9
March 1990	18.7
June 1990	18.2
October 1990	16.5
February 1991	17.9
May 1991	18.7
September 1991	16.6
January 1992	18.1
May 1992	18.2
August 1992	17.0
December 1992	17.2
April 1993	18.6
July 1993	18.4
November 1993	16.4
March 1994	18.7
June 1994	18.3
October 1994	16.6
February 1995	19.2
June 1995	19.3
September 1995	17.3
January 1996	18.4
May 1996	18.7
August 1996	19.2
December 1996	19.1
April 1997	18.2
August 1997	18.9
November 1997	18.7
March 1998	18.9
July 1998	19.1
October 1998	18.1
February 1999	18.3
June 1999	19.2
September 1999	17.6
January 2000	18.6
May 2000	18.9
September 2000	18.6
December 2000	18.8
April 2001	18.9
August 2001	18.6
November 2001	18.6
March 2002	18.6
July 2002	18.6
November 2002	18.3
February 2003	17.5
June 2003	19.1
October 2003	18.7
January 2004	18.7
May 2004	18.7
September 2004	17.6
January 2005	16.7
April 2005	16.4
August 2005	16.6
December 2005	15.2
March 2006	14.4
July 2006	15.4
November 2006	14.7
February 2007	14.4
June 2007	16.1
October 2007	15.3
February 2008	14.7
May 2008	15.3
September 2008	17.9
January 2009	17.9
April 2009	18.6
August 2009	18.8
December 2009	18.0
April 2010	18.4
July 2010	19.1
November 2010	18.2
March 2011	18.4
June 2011	19.3
October 2011	18.8
February 2012	18.6
May 2012	19.1
September 2012	18.9
January 2013	18.9
May 2013	19.2
August 2013	19.0
December 2013	18.7
April 2014	18.8
July 2014	19.2
November 2014	18.7
March 2015	19.2
July 2015	18.5
October 2015	18.3
February 2016	17.7
June 2016	17.9
September 2016	18.3
January 2017	18.8
May 2017	18.9
August 2017	19.0
December 2017	18.5
April 2018	18.7
August 2018	18.7
November 2018	18.3
March 2019	18.8
July 2019	19.2
October 2019	17.9
February 2020	18.7
June 2020	18.9
October 2020	18.5
January 2021	18.0
May 2021	19.2
September 2021	18.7
December 2021	18.5
April 2022	18.7
August 2022	19.1
December 2022	18.3
March 2023	18.2
July 2023	18.9
November 2023	18.9
February 2024	18.1
June 2024	19.0
October 2024	17.6
January 2025	18.2
May 2025	18.4
September 2025	18.2
January 2026	18.6
April 2026	18.4
August 2026	17.6

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	18.0	18.6
Feb	18.0	18.4
Mar	18.1	18.4
Apr	18.3	18.4
May	18.5	18.3
Jun	18.6	18.2
Jul	18.4	17.9
Aug	18.1	17.6
Sep	17.9	18.2
Oct	17.8	18.2
Nov	17.9	18.7
Dec	17.9	18.8

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

887 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 887 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 887 would be longer than this page and unusable with a screen reader.
Period	Deerfield Reservoir (m)
1952.75	0
1953.0833333333333	0
1953.3333333333333	1,801
1953.6666666666667	1,800
1954	1,800
1954.3333333333333	1,801
1954.5833333333333	1,797
1954.9166666666667	1,796
1955.25	1,798
1955.5	1,798
1955.8333333333333	1,795
1956.1666666666667	1,797
1956.4166666666667	1,798
1956.75	1,794
1957.0833333333333	1,795
1957.4166666666667	1,797
1957.6666666666667	1,797
1958	1,797
1958.3333333333333	1,798
1958.5833333333333	1,797
1958.9166666666667	1,795
1959.25	1,796
1959.5833333333333	1,791
1959.8333333333333	1,782
1960.1666666666667	1,785
1960.5	1,788
1960.75	1,787
1961.0833333333333	1,787
1961.4166666666667	1,789
1961.75	1,788
1962	1,789
1962.3333333333333	1,791
1962.6666666666667	1,793
1962.9166666666667	1,793
1963.25	1,795
1963.5833333333333	1,799
1963.8333333333333	1,799
1964.1666666666667	1,800
1964.5	1,801
1964.8333333333333	1,799
1965.0833333333333	1,800
1965.4166666666667	1,801
1965.75	1,799
1966	1,800
1966.3333333333333	1,801
1966.6666666666667	1,799
1967	1,800
1967.25	1,801
1967.5833333333333	1,800
1967.9166666666667	1,800
1968.1666666666667	1,801
1968.5	1,801
1968.8333333333333	1,799
1969.0833333333333	1,800
1969.4166666666667	1,801
1969.75	1,799
1970.0833333333333	1,800
1970.3333333333333	1,801
1970.6666666666667	1,799
1971	1,800
1971.25	1,801
1971.5833333333333	1,801
1971.9166666666667	1,799
1972.25	1,800
1972.5	1,801
1972.8333333333333	1,799
1973.1666666666667	1,800
1973.4166666666667	1,801
1973.75	1,799
1974.0833333333333	1,800
1974.3333333333333	1,801
1974.6666666666667	1,800
1975	1,800
1975.3333333333333	1,801
1975.5833333333333	1,800
1975.9166666666667	1,800
1976.25	1,801
1976.5	1,801
1976.8333333333333	1,799
1977.1666666666667	1,801
1977.5	1,800
1977.75	1,800
1978.0833333333333	1,801
1978.4166666666667	1,801
1978.6666666666667	1,800
1979	1,800
1979.3333333333333	1,801
1979.6666666666667	1,800
1979.9166666666667	1,799
1980.25	1,801
1980.5833333333333	1,800
1980.8333333333333	1,799
1981.1666666666667	1,801
1981.5	1,801
1981.75	1,799
1982.0833333333333	1,800
1982.4166666666667	1,797
1982.75	1,782
1983	1,787
1983.3333333333333	1,789
1983.6666666666667	1,793
1983.9166666666667	1,795
1984.25	1,797
1984.5833333333333	1,799
1984.9166666666667	1,800
1985.1666666666667	1,801
1985.5	1,800
1985.8333333333333	1,799
1986.0833333333333	1,800
1986.4166666666667	1,800
1986.75	1,800
1987	1,800
1987.3333333333333	1,801
1987.6666666666667	1,800
1988	1,800
1988.25	1,801
1988.5833333333333	1,800
1988.9166666666667	1,800
1989.1666666666667	1,800
1989.5	1,800
1989.8333333333333	1,799
1990.1666666666667	1,800
1990.4166666666667	1,800
1990.75	1,799
1991.0833333333333	1,800
1991.3333333333333	1,800
1991.6666666666667	1,799
1992	1,800
1992.3333333333333	1,800
1992.5833333333333	1,799
1992.9166666666667	1,799
1993.25	1,800
1993.5	1,800
1993.8333333333333	1,799
1994.1666666666667	1,800
1994.4166666666667	1,800
1994.75	1,799
1995.0833333333333	1,801
1995.4166666666667	1,801
1995.6666666666667	1,800
1996	1,800
1996.3333333333333	1,800
1996.5833333333333	1,801
1996.9166666666667	1,801
1997.25	1,800
1997.5833333333333	1,801
1997.8333333333333	1,800
1998.1666666666667	1,801
1998.5	1,801
1998.75	1,800
1999.0833333333333	1,800
1999.4166666666667	1,801
1999.6666666666667	1,800
2000	1,800
2000.3333333333333	1,801
2000.6666666666667	1,800
2000.9166666666667	1,800
2001.25	1,800
2001.5833333333333	1,800
2001.8333333333333	1,800
2002.1666666666667	1,800
2002.5	1,800
2002.8333333333333	1,800
2003.0833333333333	1,800
2003.4166666666667	1,801
2003.75	1,800
2004	1,800
2004.3333333333333	1,800
2004.6666666666667	1,800
2005	1,799
2005.25	1,799
2005.5833333333333	1,799
2005.9166666666667	1,798
2006.1666666666667	1,798
2006.5	1,798
2006.8333333333333	1,798
2007.0833333333333	1,798
2007.4166666666667	1,799
2007.75	1,798
2008.0833333333333	1,798
2008.3333333333333	1,798
2008.6666666666667	1,800
2009	1,800
2009.25	1,800
2009.5833333333333	1,800
2009.9166666666667	1,800
2010.25	1,800
2010.5	1,801
2010.8333333333333	1,800
2011.1666666666667	1,800
2011.4166666666667	1,801
2011.75	1,800
2012.0833333333333	1,800
2012.3333333333333	1,801
2012.6666666666667	1,801
2013	1,801
2013.3333333333333	1,801
2013.5833333333333	1,801
2013.9166666666667	1,800
2014.25	1,800
2014.5	1,801
2014.8333333333333	1,800
2015.1666666666667	1,801
2015.5	1,800
2015.75	1,800
2016.0833333333333	1,800
2016.4166666666667	1,800
2016.6666666666667	1,800
2017	1,800
2017.3333333333333	1,800
2017.5833333333333	1,801
2017.9166666666667	1,800
2018.25	1,800
2018.5833333333333	1,800
2018.8333333333333	1,800
2019.1666666666667	1,800
2019.5	1,801
2019.75	1,800
2020.0833333333333	1,800
2020.4166666666667	1,801
2020.75	1,800
2021	1,800
2021.3333333333333	1,801
2021.6666666666667	1,800
2021.9166666666667	1,800
2022.25	1,800
2022.5833333333333	1,801
2022.9166666666667	1,800
2023.1666666666667	1,800
2023.5	1,801
2023.8333333333333	1,800
2024.0833333333333	1,800
2024.4166666666667	1,801
2024.75	1,800
2025	1,800
2025.3333333333333	1,800
2025.6666666666667	1,800
2026	1,800
2026.25	1,800
2026.5833333333333	1,800

Rate and persistence

-0.05 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

Deerfield 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	1952–2026
Completeness	98.6% 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 1952 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-315.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), Deerfield Reservoir reservoir records, accessed 2026-09-02, hydrionis.com/reservoirs/reservoir-usbr-315/

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 Deerfield 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

887 monthly observations 1952–2026 Mm³

Spatially aggregatedHigh confidenceAugust 2026

Source: USBR — Reservoir operations and Colorado River data, RISE catalogue item 295. 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.