HydrionisGlobal Water Intelligence
Monitored reservoir

Millerton Lk A Friant CA

United States Geological Survey reservoir gauge 11250100 in CA, with published storage from 1941.

Storage record11250100

Storage now, against this reservoir's own record

356.57 Mm³
Stored, September 2022
84th
Percentile among 80 Seps on record
+12.7%
Against the Sep 1991–2020 average
+9.8%
Change over the 12 months to 2022-09

Storage in September 2022 was higher than most Seps on record, ranked against 80 other Seps held for this reservoir.

Storage, 1941–2022

Monthly mean storage
968 monthly values, 1941 to 2022
Monthly mean storageMonthly mean storage: Millerton Lk A Friant CA in Mm³, from 1941.75 to 2022.6666666666667.0200400600800Mm³1941.751952.16666666666671962.251972.33333333333331982.41666666666671992.52002.58333333333332012.6666666666667Year

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 968 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 968 would be longer than this page and unusable with a screen reader.
PeriodMillerton Lk A Friant CA (Mm³)
October 19412.62
February 194229.3
June 194240.5
February 194329.4
June 194334.1
October 194325.9
February 194430.3
June 1944333
October 1944136
February 1945394
June 1945509
November 1945306
March 1946337
July 1946491
November 1946199
March 1947435
July 1947369
November 1947126
March 1948166
July 1948526
November 1948172
March 1949255
July 1949416
November 194954.8
March 1950253
July 1950382
November 1950182
March 1951451
July 1951450
November 1951178
March 1952360
July 1952528
November 1952185
April 1953384
August 1953404
December 1953212
April 1954472
August 1954305
December 1954247
April 1955372
August 1955338
December 1955314
April 1956253
August 1956467
December 1956294
April 1957400
August 1957383
December 1957330
April 1958560
August 1958414
December 1958318
April 1959436
August 1959234
December 1959179
April 1960297
September 1960212
January 1961299
May 1961386
September 1961192
January 1962235
May 1962393
September 1962179
January 1963290
May 1963615
September 1963273
January 1964435
May 1964461
September 1964189
January 1965493
May 1965473
September 1965230
January 1966499
May 1966550
September 1966205
January 1967480
May 1967430
September 1967351
February 1968319
June 1968321
October 1968202
February 1969461
June 1969536
October 1969311
February 1970523
June 1970539
October 1970196
February 1971491
June 1971608
October 1971187
February 1972410
June 1972398
October 1972201
February 1973531
June 1973630
October 1973183
February 1974515
June 1974608
October 1974174
March 1975374
July 1975458
November 1975268
March 1976434
July 1976337
November 1976281
March 1977283
July 1977271
November 1977218
March 1978550
July 1978554
November 1978297
March 1979566
July 1979460
November 1979233
March 1980445
July 1980640
November 1980261
March 1981382
July 1981371
November 1981244
March 1982535
August 1982528
December 1982432
April 1983333
August 1983627
December 1983442
April 1984548
August 1984280
December 1984263
April 1985395
August 1985226
December 1985372
April 1986329
August 1986426
December 1986188
April 1987278
August 1987235
December 1987241
April 1988349
August 1988191
December 1988214
April 1989405
August 1989180
January 1990212
May 1990408
September 1990234
January 1991221
May 1991474
September 1991227
January 1992271
May 1992558
September 1992211
January 1993321
May 1993486
September 1993223
January 1994298
May 1994511
September 1994220
January 1995376
May 1995388
September 1995442
January 1996410
May 1996567
September 1996298
February 1997451
June 1997628
October 1997228
February 1998444
June 1998512
October 1998514
February 1999555
June 1999641
October 1999268
February 2000439
June 2000637
October 2000266
February 2001364
June 2001558
October 2001220
February 2002387
June 2002606
October 2002275
February 2003474
June 2003627
October 2003256
February 2004423
July 2004370
November 2004297
March 2005548
July 2005623
November 2005303
March 2006551
July 2006622
November 2006305
March 2007287
July 2007314
November 2007201
March 2008346
July 2008333
November 2008213
March 2009433
July 2009604
November 2009297
March 2010476
July 2010580
November 2010301
March 2011519
July 2011629
December 2011393
April 2012384
August 2012358
December 2012335
April 2013393
August 2013395
December 2013290
April 2014226
August 2014310
December 2014221
April 2015246
August 2015207
December 2015205
April 2016376
August 2016362
December 2016409
April 2017299
August 2017568
December 2017431
April 2018555
August 2018380
December 2018366
May 2019487
September 2019478
January 2020365
May 2020500
September 2020232
January 2021214
May 2021303
September 2021325
January 2022377
May 2022458
September 2022357

The reservoir's year

Seasonal storage profile
Each calendar month's reference average, against the most recent year
Seasonal storage profileSeasonal storage profile: 1991–2020 average, Most recent 12 months in Mm³, from 1 to 12.0200400600Mm³123456789101112Month1991–2020 average 1: 360 Mm³1991–2020 average 2: 398 Mm³1991–2020 average 3: 433 Mm³1991–2020 average 4: 455 Mm³1991–2020 average 5: 485 Mm³1991–2020 average 6: 528 Mm³1991–2020 average 7: 488 Mm³1991–2020 average 8: 377 Mm³1991–2020 average 9: 316 Mm³1991–2020 average 10: 289 Mm³1991–2020 average 11: 282 Mm³1991–2020 average 12: 313 Mm³Most recent 12 months 1: 377 Mm³Most recent 12 months 2: 334 Mm³Most recent 12 months 3: 357 Mm³Most recent 12 months 4: 425 Mm³Most recent 12 months 5: 458 Mm³Most recent 12 months 6: 447 Mm³Most recent 12 months 7: 389 Mm³Most recent 12 months 8: 321 Mm³Most recent 12 months 9: 357 Mm³Most recent 12 months 10: 377 Mm³Most recent 12 months 11: 386 Mm³Most recent 12 months 12: 411 Mm³
  • 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
Period1991–2020 average (Mm³)Most recent 12 months (Mm³)
Jan360377
Feb398334
Mar433357
Apr455425
May485458
Jun528447
Jul488389
Aug377321
Sep316357
Oct289377
Nov282386
Dec313411

Why this page shows a volume and not a percentage

Rate and persistence

+2.66 Mm³
Mean change per month over 12 months
7 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

Millerton Lk A Friant CA
Gauge location
Millerton Lk A Friant CAMillerton Lk A Friant CA — 356.57 Mm³Millerton Lk A Friant CA — 356.57 Mm³

About this data

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 existMeasured
Period held1941–2022
Completeness98.4% 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.
Continuity98% of the months between 1941 and 2022 are held. Monthly means of the publisher's own daily record.
Last read from the publisher2026-10-01
RedistributionPermitted by the upstream licences
Commercial reusePermitted by the upstream licences. No Hydrionis access tier can widen this.
MethodologyHow this was produced

Use this data

Use this data

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), Millerton Lk A Friant CA reservoir records, accessed 2026-10-05, hydrionis.com/reservoirs/reservoir-usgs-11250100/

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 Millerton Lk A Friant CA 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

968 monthly observations 1941–2022 Mm³
Spatially aggregatedHigh confidenceSeptember 2022

Source: USGS — National Water Information System, 11250100. 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.

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