Storage now, against this reservoir's own record

0.00 Mm³
Stored, August 2026
0th
Percentile among 96 Augs on record
-100.0%
Against the Aug 1991–2020 average

Storage in August 2026 was lower than almost every other Aug on record, ranked against 96 other Augs held for this reservoir. It is the lowest in the held record for this month.

Storage, 1930–2026

Monthly mean storage
1,148 monthly values, 1930 to 2026
Monthly mean storageMonthly mean storage: Hetch Hetchy Res A Hetch Hetchy CA in Mm³, from 1930.75 to 2026.5833333333333.0200400Mm³1930.751943195519671979199120032015Year

Monthly means of the publisher's daily record. Volume, not percentage of capacity: without a capacity whose definition is stated, fullness cannot be computed.

View the data behind this chart
Underlying data
PeriodHetch Hetchy Res A Hetch Hetchy CA (Mm³)
October 19300
November 19300
December 19300
April 19310
May 19310
June 19310
July 19310
August 19310
September 19310
October 19310
November 19310
December 19310
January 19320
February 19320
March 19320
April 19320
May 19320
June 19320
July 19320
August 19320
September 19320
October 19320
November 19320
December 19320
January 19330
February 19330
March 19330
April 19330
May 19330
June 19330
July 19330
August 19330
September 19330
October 19330
November 19330
December 19330
January 19340
February 19340
March 19340
April 19340
May 19340
June 19340
July 19340
August 19340
September 19340
October 19340
November 19340
December 19340
January 19350
February 19350
March 19350
April 19350
May 19350
June 19350
July 19350
August 19350
September 19350
October 19350
November 19350
December 19350
January 19360
February 19360
March 19360
April 19360
May 19360
June 19360
July 19360
August 19360
September 19360
October 19360
November 19360
December 19360
January 19370
February 19370
March 19370
April 19370
May 19370
June 19370
July 19370
August 19370
September 19370
October 19370
November 19370
December 19370
January 19380
February 19380
March 19380
April 19380
May 19380
June 19380
July 19380
August 19380
September 19380
October 19380
November 19380
December 19380
January 19390
February 19390
March 19390
April 19390
May 19390
June 19390
July 19390
August 19390
September 19390
October 19390
November 19390
December 19390
January 19400
February 19400
March 19400
April 19400
May 19400
June 19400
July 19400
August 19400
September 19400
October 19400
November 19400
December 19400
January 19410
February 19410
March 19410
April 19410
May 19410
June 19410
July 19410
August 19410
September 19410
October 19410
November 19410
December 19410
January 19420
February 19420
March 19420
April 19420
May 19420
June 19420
July 19420
August 19420
September 19420
October 19420
November 19420
December 19420
January 19430
February 19430
March 19430
April 19430
May 19430
June 19430
July 19430
August 19430
September 19430
October 19430
November 19430
December 19430
January 19440
February 19440
March 19440
April 19440
May 19440
June 19440
July 19440
August 19440
September 19440
October 19440
November 19440
December 19440
January 19450
February 19450
March 19450
April 19450
May 19450
June 19450
July 19450
August 19450
September 19450
October 19450
November 19450
December 19450
January 19460
February 19460
March 19460
April 19460
May 19460
June 19460
July 19460
August 19460
September 19460
October 19460
November 19460
December 19460
January 19470
February 19470
March 19470
April 19470
May 19470
June 19470
July 19470
August 19470
September 19470
October 19470
November 19470
December 19470
January 19480
February 19480
March 19480
April 19480
May 19480
June 19480
July 19480
August 19480
September 19480
October 19480
November 19480
December 19480
January 19490
February 19490
March 19490
April 19490
May 19490
June 19490
July 19490
August 19490
September 19490
October 19490
November 19490
December 19490
January 19500
February 19500
March 19500
April 19500
May 19500
June 19500
July 19500
August 19500
September 19500
October 19500
November 19500
December 19500
January 19510
February 19510
March 19510
April 19510
May 19510
June 19510
July 19510
August 19510
September 19510
October 19510
November 19510
December 19510
January 19520
February 19520
March 19520
April 19520
May 19520
June 19520
July 19520
August 19520
September 19520
October 19520
November 19520
December 19520
January 19530
February 19530
March 19530
April 19530
May 19530
June 19530
July 19530
August 19530
September 19530
October 19530
November 19530
December 19530
January 19540
February 19540
March 19540
April 19540
May 19540
June 19540
July 19540
August 19540
September 19540
October 19540
November 19540
December 19540
January 19550
February 19550
March 19550
April 19550
May 19550
June 19550
July 19550
August 19550
September 19550
October 19550
November 19550
December 19550
January 19560
February 19560
March 19560
April 19560
May 19560
June 19560
July 19560
August 19560
September 19560
October 19560
November 19560
December 19560
January 19570
February 19570
March 19570
April 19570
May 19570
June 19570
July 19570
August 19570
September 19570
October 19570
November 19570
December 19570
January 19580
February 19580
March 19580
April 19580
May 19580
June 19580
July 19580
August 19580
September 19580
October 19580
November 19580
December 19580
January 19590
February 19590
March 19590
April 19590
May 19590
June 19590
July 19590
August 19590
September 19590
October 19590
November 19590
December 19590
January 19600
February 19600
March 19600
April 19600
May 19600
June 19600
July 19600
August 19600
September 19600
October 19600
November 19600
December 19600
January 19610
February 19610
March 19610
April 19610
May 19610
June 19610
July 19610
August 19610
September 19610
October 19610
November 19610
December 19610
January 19620
February 19620
March 19620
April 19620
May 19620
June 19620
July 19620
August 19620
September 19620
October 19620
November 19620
December 19620
January 19630
February 19630
March 19630
April 19630
May 19630
June 19630
July 19630
August 19630
September 19630
October 19630
November 19630
December 19630
January 19640
February 19640
March 19640
April 19640
May 19640
June 19640
July 19640
August 19640
September 19640
October 19640
November 19640
December 19640
January 19650
February 19650
March 19650
April 19650
May 19650
June 19650
July 19650
August 19650
September 19650
October 19650
November 19650
December 19650
January 19660
February 19660
March 19660
April 19660
May 19660
June 19660
July 19660
August 19660
September 19660
October 19660
November 19660
December 19660
January 19670
February 19670
March 19670
April 19670
May 19670
June 19670
July 19670
August 19670
September 19670
October 19670
November 19670
December 19670
January 19680
February 19680
March 19680
April 19680
May 19680
June 19680
July 19680
August 19680
September 19680
October 19680
November 19680
December 19680
January 19690
February 19690
March 19690
April 19690
May 19690
June 19690
July 19690
August 19690
September 19690
October 19690
November 19690
December 19690
January 19700
February 19700
March 19700
April 19700
May 19700
June 19700
July 19700
August 19700
September 19700
October 19700
November 19700
December 19700
January 19710
February 19710
March 19710
April 19710
May 19710
June 19710
July 19710
August 19710
September 19710
October 19710
November 19710
December 19710
January 19720
February 19720
March 19720
April 19720
May 19720
June 19720
July 19720
August 19720
September 19720
October 1972229
November 1972185
December 1972153
January 1973132
February 1973105
March 197372.8
April 197356.1
May 1973206
June 1973439
July 1973438
August 1973400
September 1973345
October 1973289
November 1973272
December 1973262
January 1974249
February 1974229
March 1974204
April 1974207
May 1974306
June 1974434
July 1974443
August 1974422
September 1974365
October 1974305
November 1974247
December 1974196
January 1975148
February 1975111
March 197581.9
April 197558.3
May 1975123
June 1975382
July 1975433
August 1975405
September 1975351
October 1975303
November 1975280
December 1975232
January 1976180
February 1976140
March 1976120
April 1976127
May 1976219
June 1976258
July 1976233
August 1976200
September 1976166
October 1976134
November 1976103
December 197679.1
January 197753.4
February 197735.9
March 197731.4
April 197743.9
May 197788.3
June 1977165
July 1977187
August 1977170
September 1977149
October 1977131
November 1977112
December 1977103
January 1978115
February 197891.2
March 197881.1
April 1978102
May 1978199
June 1978348
July 1978433
August 1978438
September 1978416
October 1978373
November 1978312
December 1978257
January 1979217
February 1979185
March 1979165
April 1979167
May 1979271
June 1979425
July 1979436
August 1979392
September 1979335
October 1979280
November 1979238
December 1979198
January 1980221
February 1980247
March 1980248
April 1980245
May 1980301
June 1980352
July 1980445
August 1980433
September 1980384
October 1980328
November 1980272
December 1980218
January 1981163
February 1981137
March 1981137
April 1981166
May 1981318
June 1981436
July 1981410
August 1981352
September 1981292
October 1981242
November 1981229
December 1981234
January 1982240
February 1982235
March 1982243
April 1982258
May 1982332
June 1982422
July 1982446
August 1982440
September 1982410
October 1982408
November 1982421
December 1982388
January 1983347
February 1983327
March 1983317
April 1983246
May 1983169
June 1983379
July 1983445
August 1983446
September 1983426
October 1983384
November 1983356
December 1983373
January 1984378
February 1984346
March 1984326
April 1984339
May 1984399
June 1984447
July 1984444
August 1984409
September 1984356
October 1984302
November 1984263
December 1984235
January 1985195
February 1985157
March 1985129
April 1985163
May 1985290
June 1985410
July 1985399
August 1985347
September 1985294
October 1985255
November 1985232
December 1985225
January 1986220
February 1986229
March 1986302
April 1986328
May 1986309
June 1986430
July 1986445
August 1986419
September 1986366
October 1986317
November 1986257
December 1986207
January 1987170
February 1987153
March 1987150
April 1987177
May 1987304
June 1987379
July 1987373
August 1987342
September 1987307
October 1987267
November 1987237
December 1987215
January 1988197
February 1988178
March 1988171
April 1988208
May 1988294
June 1988383
July 1988366
August 1988338
September 1988307
October 1988275
November 1988239
December 1988198
January 1989160
February 1989132
March 1989153
April 1989233
May 1989364
June 1989441
July 1989427
August 1989377
September 1989318
October 1989274
November 1989237
December 1989197
January 1990156
February 1990125
March 1990112
April 1990152
May 1990252
June 1990308
July 1990288
August 1990246
September 1990194
October 1990147
November 1990122
December 199092.3
January 199156.0
February 199134.9
March 199149.3
April 199182.3
May 1991152
June 1991349
July 1991402
August 1991359
September 1991311
October 1991269
November 1991238
December 1991209
January 1992173
February 1992152
March 1992145
April 1992164
May 1992274
June 1992312
July 1992306
August 1992284
September 1992251
October 1992220
November 1992195
December 1992164
January 1993137
February 1993112
March 199394.7
April 1993103
May 1993232
June 1993369
July 1993443
August 1993431
September 1993403
October 1993371
November 1993344
December 1993324
January 1994311
February 1994300
March 1994275
April 1994264
May 1994340
June 1994436
July 1994423
August 1994387
September 1994347
October 1994309
November 1994282
December 1994258
January 1995236
February 1995195
March 1995180
April 1995179
May 1995176
June 1995263
July 1995433
August 1995443
September 1995432
October 19950
November 19950
December 19950
January 19960
February 19960
March 19960
April 19960
May 19960
June 19960
July 19960
August 19960
September 19960
October 19960
November 19960
December 19960
January 19970
February 19970
March 19970
April 19970
May 19970
June 19970
July 19970
August 19970
September 19970
October 19970
November 19970
December 19970
January 19980
February 19980
March 19980
April 19980
May 19980
June 19980
July 19980
August 19980
September 19980
October 19980
November 19980
December 19980
January 19990
February 19990
March 19990
April 19990
May 19990
June 19990
July 19990
August 19990
September 19990
October 19990
November 19990
December 19990
January 20000
February 20000
March 20000
April 20000
May 20000
June 20000
July 20000
August 20000
September 20000
October 20000
November 20000
December 20000
January 20010
February 20010
March 20010
April 20010
May 20010
June 20010
July 20010
August 20010
September 20010
October 20010
November 20010
December 20010
January 20020
February 20020
March 20020
April 20020
May 20020
June 20020
July 20020
August 20020
September 20020
October 20020
November 20020
December 20020
January 20030
February 20030
March 20030
April 20030
May 20030
June 20030
July 20030
August 20030
September 20030
October 20030
November 20030
December 20030
January 20040
February 20040
March 20040
April 20040
May 20040
June 20040
July 20040
August 20040
September 20040
October 20040
November 20040
December 20040
January 20050
February 20050
March 20050
April 20050
May 20050
June 20050
July 20050
August 20050
September 20050
October 20050
November 20050
December 20050
January 20060
February 20060
March 20060
April 20060
May 20060
June 20060
July 20060
August 20060
September 20060
October 20060
November 20060
December 20060
January 20070
February 20070
March 20070
April 20070
May 20070
June 20070
July 20070
August 20070
September 20070
October 20070
November 20070
December 20070
January 20080
February 20080
March 20080
April 20080
May 20080
June 20080
July 20080
August 20080
September 20080
October 20080
November 20080
December 20080
January 20090
February 20090
March 20090
April 20090
May 20090
June 20090
July 20090
August 20090
September 20090
October 20090
November 20090
December 20090
January 20100
February 20100
March 20100
April 20100
May 20100
June 20100
July 20100
August 20100
September 20100
October 20100
November 20100
December 20100
January 20110
February 20110
March 20110
April 20110
May 20110
June 20110
July 20110
August 20110
September 20110
October 20110
November 20110
December 20110
January 20120
February 20120
March 20120
April 20120
May 20120
June 20120
July 20120
August 20120
September 20120
October 20120
November 20120
December 20120
January 20130
February 20130
March 20130
April 20130
May 20130
June 20130
July 20130
August 20130
September 20130
October 20130
November 20130
December 20130
January 20140
February 20140
March 20140
April 20140
May 20140
June 20140
July 20140
August 20140
September 20140
October 20140
November 20140
December 20140
January 20150
February 20150
March 20150
April 20150
May 20150
June 20150
July 20150
August 20150
September 20150
October 20150
November 20150
December 20150
January 20160
February 20160
March 20160
April 20160
May 20160
June 20160
July 20160
August 20160
September 20160
October 20160
November 20160
December 20160
January 20170
February 20170
March 20170
April 20170
May 20170
June 20170
July 20170
August 20170
September 20170
October 20170
November 20170
December 20170
January 20180
February 20180
March 20180
April 20180
May 20180
June 20180
July 20180
August 20180
September 20180
October 20180
November 20180
December 20180
January 20190
February 20190
March 20190
April 20190
May 20190
June 20190
July 20190
August 20190
September 20190
October 20190
November 20190
December 20190
January 20200
February 20200
March 20200
April 20200
May 20200
June 20200
July 20200
August 20200
September 20200
October 20200
November 20200
December 20200
January 20210
February 20210
March 20210
April 20210
May 20210
June 20210
July 20210
August 20210
September 20210
October 20210
November 20210
December 20210
January 20220
February 20220
March 20220
April 20220
May 20220
June 20220
July 20220
August 20220
September 20220
October 20220
November 20220
December 20220
January 20230
February 20230
March 20230
April 20230
May 20230
June 20230
July 20230
August 20230
September 20230
October 20230
November 20230
December 20230
January 20240
February 20240
March 20240
April 20240
May 20240
June 20240
July 20240
August 20240
September 20240
October 20240
November 20240
December 20240
January 20250
February 20250
March 20250
April 20250
May 20250
June 20250
July 20250
August 20250
September 20250
October 20250
November 20250
December 20250
January 20260
February 20260
March 20260
April 20260
May 20260
June 20260
July 20260
August 20260

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 12.020406080Mm³123456789101112Month1991–2020 average 1: 30.5 Mm³1991–2020 average 2: 26.4 Mm³1991–2020 average 3: 24.8 Mm³1991–2020 average 4: 26.4 Mm³1991–2020 average 5: 39.1 Mm³1991–2020 average 6: 57.6 Mm³1991–2020 average 7: 66.9 Mm³1991–2020 average 8: 63.5 Mm³1991–2020 average 9: 58.2 Mm³1991–2020 average 10: 39.0 Mm³1991–2020 average 11: 35.3 Mm³1991–2020 average 12: 31.8 Mm³Most recent 12 months 1: 0 Mm³Most recent 12 months 2: 0 Mm³Most recent 12 months 3: 0 Mm³Most recent 12 months 4: 0 Mm³Most recent 12 months 5: 0 Mm³Most recent 12 months 6: 0 Mm³Most recent 12 months 7: 0 Mm³Most recent 12 months 8: 0 Mm³Most recent 12 months 9: 0 Mm³Most recent 12 months 10: 0 Mm³Most recent 12 months 11: 0 Mm³Most recent 12 months 12: 0 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)
Jan30.50
Feb26.40
Mar24.80
Apr26.40
May39.10
Jun57.60
Jul66.90
Aug63.50
Sep58.20
Oct39.00
Nov35.30
Dec31.80

Rate and persistence

24 of 24
Months in the last two years 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

Hetch Hetchy Res A Hetch Hetchy CA
Gauge location
Hetch Hetchy Res A Hetch Hetchy CAHetch Hetchy Res A Hetch Hetchy CA — 0.00 Mm³Hetch Hetchy Res A Hetch Hetchy CA — 0.00 Mm³

Where this comes from

1,148 monthly observations 19302026 Mm³
Spatially aggregatedHigh confidenceAugust 2026

Source: USGSNational Water Information System, 11275500. 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 25 August 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.