Fern Ridge Lake, OR — storage

Storage now, against this reservoir's own record

102.77 Mm³

Stored, September 1974

66th

Percentile among 33 Seps on record

+16.0%

Change over the 12 months to 1974-09

Storage in September 1974 was around the middle of the Sep record, ranked against 33 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, 1941–1974

Monthly mean storage

393 monthly values, 1941 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 393 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 393 would be longer than this page and unusable with a screen reader.
Period	Fern Ridge Lake Near Elmira, OR (Mm³)
December 1941	43.5
February 1942	29.7
March 1942	47.8
May 1942	74.7
July 1942	85.0
August 1942	75.9
November 1942	27.5
December 1942	97.3
February 1943	89.8
April 1943	124
May 1943	125
July 1943	119
September 1943	107
October 1943	105
December 1943	4.98
February 1944	12.3
March 1944	34.0
May 1944	66.3
July 1944	70.9
August 1944	68.0
October 1944	61.1
November 1944	11.3
January 1945	8.99
March 1945	71.3
April 1945	107
June 1945	124
August 1945	115
September 1945	110
November 1945	12.1
January 1946	34.7
February 1946	28.2
April 1946	101
May 1946	111
July 1946	110
September 1946	93.0
October 1946	22.7
December 1946	11.6
February 1947	35.3
March 1947	79.7
May 1947	119
July 1947	122
August 1947	120
October 1947	65.9
December 1947	9.53
January 1948	49.7
March 1948	69.2
April 1948	108
June 1948	124
August 1948	118
September 1948	114
November 1948	9.12
January 1949	9.10
February 1949	52.3
April 1949	93.2
June 1949	119
July 1949	114
September 1949	89.6
October 1949	15.6
December 1949	9.10
February 1950	32.8
March 1950	68.2
May 1950	120
July 1950	118
August 1950	110
October 1950	46.9
December 1950	10.3
January 1951	37.6
March 1951	68.2
May 1951	104
June 1951	106
August 1951	78.4
September 1951	24.9
November 1951	9.17
January 1952	9.22
February 1952	29.4
April 1952	96.9
June 1952	106
July 1952	108
September 1952	62.8
November 1952	10.1
December 1952	9.08
February 1953	36.6
March 1953	67.2
May 1953	123
July 1953	123
August 1953	113
October 1953	37.9
December 1953	19.8
January 1954	26.6
March 1954	65.5
May 1954	121
June 1954	123
August 1954	105
October 1954	35.7
November 1954	14.1
January 1955	9.31
February 1955	25.9
April 1955	111
June 1955	124
July 1955	121
September 1955	62.0
November 1955	14.3
December 1955	58.8
February 1956	35.4
April 1956	101
May 1956	113
July 1956	110
August 1956	102
October 1956	27.7
December 1956	9.82
January 1957	7.81
March 1957	85.2
May 1957	126
June 1957	126
August 1957	111
October 1957	40.5
November 1957	13.0
January 1958	16.3
March 1958	76.3
April 1958	112
June 1958	127
July 1958	122
September 1958	89.6
November 1958	16.3
December 1958	9.77
February 1959	37.1
April 1959	106
May 1959	117
July 1959	113
September 1959	63.6
October 1959	30.0
December 1959	8.75
February 1960	45.2
March 1960	82.5
May 1960	125
June 1960	127
August 1960	116
October 1960	62.8
November 1960	22.8
January 1961	10.2
March 1961	79.1
April 1961	109
June 1961	125
August 1961	113
September 1961	108
November 1961	16.4
December 1961	16.6
February 1962	28.0
April 1962	110
May 1962	124
July 1962	119
September 1962	108
October 1962	62.6
December 1962	11.6
February 1963	33.9
March 1963	65.4
May 1963	127
July 1963	124
August 1963	120
October 1963	59.7
November 1963	16.8
January 1964	38.9
March 1964	65.8
April 1964	99.0
June 1964	107
August 1964	97.7
September 1964	64.8
November 1964	9.29
January 1965	50.0
February 1965	31.5
April 1965	66.5
May 1965	80.8
July 1965	77.9
September 1965	67.2
October 1965	35.2
December 1965	13.0
February 1966	31.0
March 1966	78.1
May 1966	117
July 1966	107
August 1966	99.1
October 1966	40.6
December 1966	10.4
January 1967	15.8
March 1967	72.5
April 1967	111
June 1967	127
August 1967	111
September 1967	102
November 1967	15.7
January 1968	11.1
February 1968	42.8
April 1968	117
June 1968	125
July 1968	118
September 1968	109
October 1968	72.5
December 1968	21.8
February 1969	33.4
March 1969	75.9
May 1969	110
July 1969	111
August 1969	101
October 1969	65.1
December 1969	12.9
January 1970	39.2
March 1970	76.8
May 1970	113
June 1970	113
August 1970	96.0
September 1970	87.7
November 1970	11.0
January 1971	48.3
February 1971	52.3
April 1971	125
June 1971	126
July 1971	123
September 1971	108
November 1971	16.8
December 1971	11.0
February 1972	40.5
March 1972	100.0
May 1972	126
July 1972	120
August 1972	111
October 1972	77.0
December 1972	9.93
January 1973	15.4
March 1973	72.1
May 1973	115
June 1973	113
August 1973	95.8
October 1973	63.9
November 1973	26.2
January 1974	52.8
February 1974	37.9
April 1974	118
June 1974	125
July 1974	120
September 1974	103

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

+1.18 Mm³

Mean change 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

Fern Ridge Lake Near Elmira, 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	1941–1974
Completeness	96.3% 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	96% of the months between 1941 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-14168000.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), Fern Ridge Lake Near Elmira, OR reservoir records, accessed 2026-10-05, hydrionis.com/reservoirs/reservoir-usgs-14168000/

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 Fern Ridge Lake Near Elmira, 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

393 monthly observations 1941–1974 Mm³

Spatially aggregatedHigh confidenceSeptember 1974

Source: USGS — National Water Information System, 14168000. 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.