Cottage Grove Lake, OR — storage

Storage now, against this reservoir's own record

21.13 Mm³

Stored, September 1974

48th

Percentile among 32 Seps on record

-27.9%

Change over the 12 months to 1974-09

Storage in September 1974 was around the middle of the Sep record, ranked against 32 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, 1942–1974

Monthly mean storage

384 monthly values, 1942 to 1974

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 384 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 384 would be longer than this page and unusable with a screen reader.
Period	Cottage Grove Lake Nr Cottage Grove, OR (Mm³)
October 1942	0.0002
December 1942	11.2
January 1943	9.14
March 1943	19.2
April 1943	34.4
June 1943	41.2
August 1943	39.4
September 1943	34.6
November 1943	4.09
December 1943	1.09
February 1944	5.11
April 1944	32.0
May 1944	40.9
July 1944	40.8
August 1944	40.1
October 1944	11.6
December 1944	3.70
January 1945	3.90
March 1945	22.7
April 1945	34.4
June 1945	41.1
August 1945	39.2
September 1945	23.6
November 1945	4.65
December 1945	5.52
February 1946	9.33
April 1946	33.7
May 1946	39.5
July 1946	40.4
August 1946	39.0
October 1946	8.94
December 1946	4.16
January 1947	3.92
March 1947	25.0
April 1947	36.9
June 1947	40.4
August 1947	39.3
September 1947	38.3
November 1947	4.36
December 1947	4.21
February 1948	10.4
April 1948	34.5
May 1948	41.6
July 1948	40.4
September 1948	14.2
October 1948	5.56
December 1948	5.79
January 1949	4.24
March 1949	21.7
May 1949	41.2
June 1949	40.7
August 1949	36.1
September 1949	31.0
November 1949	3.60
January 1950	5.87
February 1950	7.47
April 1950	34.6
May 1950	40.9
July 1950	39.8
September 1950	28.0
October 1950	11.6
December 1950	3.99
January 1951	5.35
March 1951	21.8
May 1951	36.5
June 1951	37.1
August 1951	29.2
September 1951	20.8
November 1951	3.91
January 1952	3.93
February 1952	9.15
April 1952	34.1
May 1952	39.4
July 1952	39.2
September 1952	23.4
October 1952	10.4
December 1952	3.82
January 1953	8.10
March 1953	21.8
May 1953	39.4
June 1953	39.5
August 1953	34.5
September 1953	23.4
November 1953	6.97
January 1954	5.74
February 1954	8.43
April 1954	28.2
May 1954	32.2
July 1954	32.0
September 1954	22.4
October 1954	7.36
December 1954	3.68
January 1955	3.69
March 1955	19.5
May 1955	37.9
June 1955	39.3
August 1955	32.5
September 1955	8.96
November 1955	6.25
January 1956	6.09
February 1956	10.4
April 1956	28.6
May 1956	37.8
July 1956	39.1
September 1956	21.3
October 1956	8.02
December 1956	4.52
January 1957	3.64
March 1957	24.4
May 1957	35.3
June 1957	39.6
August 1957	20.8
September 1957	6.93
November 1957	4.50
January 1958	4.62
February 1958	11.4
April 1958	28.5
May 1958	35.1
July 1958	39.4
September 1958	17.9
October 1958	7.18
December 1958	3.96
February 1959	9.95
March 1959	18.7
May 1959	37.7
June 1959	40.0
August 1959	25.0
October 1959	6.88
November 1959	3.55
January 1960	4.25
February 1960	12.6
April 1960	29.4
June 1960	39.9
July 1960	38.3
September 1960	23.7
October 1960	8.76
December 1960	3.74
February 1961	18.2
March 1961	18.8
May 1961	37.3
June 1961	39.6
August 1961	30.8
October 1961	10.8
November 1961	7.59
January 1962	3.57
February 1962	8.61
April 1962	28.3
June 1962	39.5
July 1962	38.1
September 1962	26.1
October 1962	12.2
December 1962	8.09
February 1963	10.4
March 1963	21.1
May 1963	39.0
June 1963	39.7
August 1963	38.0
October 1963	10.3
November 1963	4.32
January 1964	11.1
February 1964	8.54
April 1964	28.5
June 1964	38.0
July 1964	38.2
September 1964	15.4
October 1964	7.52
December 1964	15.6
February 1965	8.45
March 1965	16.3
May 1965	34.9
June 1965	35.4
August 1965	26.9
October 1965	4.92
November 1965	3.60
January 1966	7.93
February 1966	8.72
April 1966	27.7
June 1966	27.0
July 1966	23.1
September 1966	2.10
October 1966	0.010
December 1966	3.92
February 1967	9.23
March 1967	18.9
May 1967	37.5
June 1967	39.2
August 1967	23.0
October 1967	7.28
November 1967	3.74
January 1968	4.05
February 1968	11.9
April 1968	26.7
June 1968	30.8
July 1968	27.7
September 1968	13.0
October 1968	8.89
December 1968	4.82
February 1969	9.02
March 1969	18.4
May 1969	35.2
July 1969	39.8
August 1969	36.9
October 1969	9.04
November 1969	0.218
January 1970	14.6
March 1970	20.1
April 1970	26.2
June 1970	38.5
July 1970	34.9
September 1970	16.1
November 1970	1.23
December 1970	2.23
February 1971	10.3
March 1971	17.8
May 1971	36.8
July 1971	38.3
August 1971	27.6
October 1971	0.132
November 1971	1.74
January 1972	13.2
March 1972	26.0
April 1972	30.0
June 1972	38.9
July 1972	37.2
September 1972	20.1
November 1972	1.52
December 1972	2.19
February 1973	10.6
March 1973	22.1
May 1973	38.4
July 1973	36.4
August 1973	32.9
October 1973	10.8
November 1973	5.77
January 1974	7.62
March 1974	18.3
April 1974	28.7
June 1974	39.7
July 1974	39.1
September 1974	21.1

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

-0.68 Mm³

Mean drawdown per month over 12 months

5 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

Cottage Grove Lake Nr Cottage Grove, OR

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	1942–1974
Completeness	97.0% 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 1942 and 1974 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-14153000.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), Cottage Grove Lake Nr Cottage Grove, OR reservoir records, accessed 2026-10-05, hydrionis.com/reservoirs/reservoir-usgs-14153000/

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 Cottage Grove Lake Nr Cottage Grove, OR 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

384 monthly observations 1942–1974 Mm³

Spatially aggregatedHigh confidenceSeptember 1974

Source: USGS — National Water Information System, 14153000. 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.