Mackay Res — storage

Storage now, against this reservoir's own record

0.43 Mm³

Stored, September 1959

14th

Percentile among 29 Seps on record

-96.6%

Change over the 12 months to 1959-09

Storage in September 1959 was lower than most Seps on record, ranked against 29 other Seps held for this reservoir.

No percentage departure from the Sep average is published here. No long-term average is held for this month, so there is nothing to compare with.

Storage, 1930–1959

Monthly mean storage

348 monthly values, 1930 to 1959

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 348 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 348 would be longer than this page and unusable with a screen reader.
Period	Mackay Res Nr Mackay ID (Mm³)
October 1930	0.655
November 1930	6.85
January 1931	20.8
February 1931	24.7
April 1931	29.4
May 1931	28.4
July 1931	6.36
August 1931	1.50
October 1931	0
November 1931	3.39
January 1932	14.3
February 1932	17.8
March 1932	20.1
May 1932	20.7
June 1932	18.9
August 1932	5.59
September 1932	3.57
November 1932	8.25
December 1932	15.5
February 1933	24.7
March 1933	27.0
April 1933	28.9
June 1933	17.5
July 1933	2.93
September 1933	0.0003
October 1933	0
December 1933	8.32
January 1934	14.3
March 1934	20.7
April 1934	21.5
June 1934	6.06
July 1934	0.377
August 1934	0
October 1934	0.0020
November 1934	3.20
January 1935	13.8
February 1935	17.0
April 1935	21.2
May 1935	21.0
July 1935	29.0
August 1935	6.45
October 1935	1.06
November 1935	5.27
December 1935	10.7
February 1936	20.0
March 1936	22.4
May 1936	23.5
June 1936	28.9
August 1936	1.97
September 1936	3.51
November 1936	4.29
December 1936	12.5
January 1937	18.2
March 1937	24.9
April 1937	26.9
June 1937	17.5
July 1937	7.15
September 1937	0.168
October 1937	0.199
December 1937	8.01
January 1938	13.4
March 1938	20.3
April 1938	22.9
May 1938	33.9
July 1938	48.2
August 1938	37.6
October 1938	39.4
November 1938	43.4
January 1939	46.5
February 1939	47.6
April 1939	48.2
May 1939	47.8
July 1939	29.5
August 1939	13.4
September 1939	10.2
November 1939	12.1
December 1939	19.7
February 1940	29.0
March 1940	31.6
May 1940	31.9
June 1940	31.0
August 1940	3.14
September 1940	4.58
November 1940	18.0
December 1940	24.8
January 1941	30.1
March 1941	35.9
April 1941	37.6
June 1941	49.1
July 1941	42.8
September 1941	27.9
October 1941	32.5
December 1941	42.4
January 1942	44.2
February 1942	43.6
April 1942	46.2
May 1942	47.3
July 1942	43.5
August 1942	23.5
October 1942	22.8
November 1942	30.4
January 1943	39.2
February 1943	40.3
April 1943	40.8
May 1943	45.7
June 1943	45.9
August 1943	41.1
September 1943	31.8
November 1943	41.4
December 1943	44.8
February 1944	46.3
March 1944	47.4
May 1944	47.7
June 1944	49.6
August 1944	38.1
September 1944	22.6
October 1944	30.1
December 1944	43.2
January 1945	44.3
March 1945	45.6
April 1945	46.2
June 1945	48.8
July 1945	45.0
September 1945	13.2
October 1945	19.8
November 1945	27.9
January 1946	40.4
February 1946	44.1
April 1946	47.6
May 1946	48.5
July 1946	38.7
August 1946	16.4
October 1946	24.6
November 1946	35.1
January 1947	46.3
February 1947	46.6
March 1947	46.5
May 1947	47.5
June 1947	48.5
August 1947	16.4
September 1947	8.46
November 1947	22.4
December 1947	30.9
February 1948	41.6
March 1948	45.4
May 1948	44.9
June 1948	47.7
July 1948	41.6
September 1948	8.68
October 1948	16.3
December 1948	34.4
January 1949	40.1
March 1949	46.4
April 1949	46.8
June 1949	45.4
July 1949	28.6
August 1949	7.68
October 1949	4.34
November 1949	14.3
January 1950	28.5
February 1950	32.5
April 1950	37.8
May 1950	33.9
July 1950	33.4
August 1950	8.59
October 1950	12.4
November 1950	21.7
December 1950	29.8
February 1951	40.7
March 1951	44.1
May 1951	49.4
June 1951	49.1
August 1951	43.0
September 1951	34.4
November 1951	44.0
December 1951	47.9
February 1952	46.6
March 1952	44.1
April 1952	41.5
June 1952	47.0
July 1952	47.5
September 1952	24.6
October 1952	31.2
December 1952	44.4
January 1953	46.4
March 1953	46.8
April 1953	47.1
June 1953	42.8
July 1953	44.3
August 1953	24.1
October 1953	14.0
November 1953	22.8
January 1954	37.0
February 1954	41.4
April 1954	46.4
May 1954	40.7
July 1954	41.2
August 1954	19.1
September 1954	8.44
November 1954	8.97
December 1954	17.9
February 1955	28.7
March 1955	31.7
May 1955	33.7
June 1955	28.9
August 1955	12.5
September 1955	1.16
November 1955	5.63
December 1955	14.3
January 1956	21.2
March 1956	29.9
April 1956	34.1
June 1956	49.7
July 1956	43.8
September 1956	12.8
October 1956	14.8
December 1956	30.8
January 1957	36.4
March 1957	43.5
April 1957	45.9
May 1957	47.1
July 1957	50.9
August 1957	21.1
October 1957	21.6
November 1957	28.4
January 1958	38.1
February 1958	40.9
April 1958	44.9
May 1958	41.7
June 1958	47.0
August 1958	20.8
September 1958	12.8
November 1958	13.8
December 1958	23.9
February 1959	36.5
March 1959	40.4
May 1959	34.4
June 1959	20.4
August 1959	1.60
September 1959	0.434

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.

Rate and persistence

-1.03 Mm³

Mean drawdown per month over 12 months

4 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

Mackay Res Nr Mackay ID

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 Geological Survey — National Water Information System · US Government work — public domain
How the values came to exist	Measured
Period held	1930–1959
Completeness	96.7% 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	97% of the months between 1930 and 1959 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-usgs-13126000.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), Mackay Res Nr Mackay ID reservoir records, accessed 2026-10-05, hydrionis.com/reservoirs/reservoir-usgs-13126000/

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 Mackay Res Nr Mackay ID 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

348 monthly observations 1930–1959 Mm³

Spatially aggregatedHigh confidenceSeptember 1959

Source: USGS — National Water Information System, 13126000. Licence: Open.

Method: Monthly mean of daily reservoir storage published by the USGS in acre-feet and converted to millions of cubic metres. Months with fewer than 20 days of record are not published rather than averaged from a partial month.

Reservoir storage is managed as well as observed: a drawdown may reflect an operating rule, flood-control rule curve or scheduled release rather than a shortage. Compare a month against the same month in other years, and do not read a fall as a supply signal without knowing the operating regime.

Retrieved 1 October 2026.

Monthly mean of daily reservoir storage published by the USGS in acre-feet and converted to millions of cubic metres. Months with fewer than 20 days of record are not published rather than averaged from a partial month.