HydrionisGlobal Water Intelligence
Monitored reservoir

San Carlos Reservoir At Coolidge Dam, AZ

United States Geological Survey reservoir gauge 09469000 in AZ, with published storage from 1987.

Storage record09469000

Storage now, against this reservoir's own record

1.19 Mm³
Stored, August 2026
61st
Percentile among 39 Augs on record
-90.9%
Against the Aug 1991–2020 average
-95.7%
Change over the 12 months to 2026-08

Storage in August 2026 was around the middle of the Aug record, ranked against 39 other Augs held for this reservoir.

Storage, 1987–2026

Monthly mean storage
467 monthly values, 1987 to 2026
Monthly mean storageMonthly mean storage: San Carlos Reservoir At Coolidge Dam, AZ in Mm³, from 1987.75 to 2026.5833333333333.0200400600800Mm³1987.751992.66666666666671997.58333333333332002.52007.41666666666672012.33333333333332017.252022.1666666666667Year

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
PeriodSan Carlos Reservoir At Coolidge Dam, AZ (Mm³)
October 1987593
November 1987205
December 19870
January 19880
February 19880
March 19880
April 19880
May 19880
June 19880
July 19880
August 19880
September 19880
October 19880
November 19880
December 19880
January 19890
February 19890
March 19890
April 19890
May 19890
June 19890
July 19890
August 19890
September 19890
October 19890
November 19890
December 19890
January 19900
February 19900
March 19900
April 19900
May 19900
June 19900
July 19900
August 19900
September 19900
October 19900
November 19900
December 19900
January 19910
February 19910
March 19910
April 19910
May 19910
June 19910
July 19910
August 19910
September 19910
October 19910
November 19910
December 19910
January 19920
February 19920
March 19920
April 19920
May 19920
June 19920
July 19920
August 19920
September 19920
October 19920
November 19920
December 19920
January 19930
February 19930
March 19930
April 19930
May 19930
June 19930
July 19930
August 19930
September 19930
October 19930
November 19930
December 19930
January 19940
February 19940
March 19940
April 19940
May 19940
June 19940
July 19940
August 19940
September 19940
October 19940
November 19940
December 19940
January 19950
February 19950
March 19950
April 19950
May 19950
June 19950
July 19950
August 19950
September 19950
October 19950
November 19950
December 19950
January 19960
February 19960
March 19960
April 19960
May 19960
June 19960
July 199699.0
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 20112.77
September 20114.99
October 20117.29
November 20118.17
December 201111.4
January 201223.5
February 201229.5
March 201230.2
April 201226.0
May 201213.6
June 20122.86
July 20121.93
August 20122.46
September 20128.05
October 20127.29
November 20126.01
December 20124.59
January 20137.48
February 201313.1
March 201313.7
April 201310.2
May 20130.605
June 20130.468
July 20132.57
August 201316.6
September 201368.8
October 2013119
November 2013149
December 2013153
January 2014159
February 2014153
March 2014135
April 2014101
May 201470.7
June 201443.8
July 201418.7
August 201419.9
September 201431.5
October 201478.3
November 201489.0
December 201491.9
January 201596.8
February 2015156
March 2015175
April 2015160
May 2015133
June 201597.8
July 201560.0
August 201529.5
September 20159.18
October 201518.0
November 201537.0
December 201561.0
January 201693.5
February 2016122
March 2016132
April 2016111
May 201679.3
June 201647.5
July 201629.2
August 201619.2
September 201618.3
October 201625.8
November 201633.2
December 201640.0
January 201795.3
February 2017216
March 2017295
April 2017289
May 2017257
June 2017215
July 2017164
August 2017154
September 2017119
October 201793.6
November 201778.7
December 201770.0
January 201874.8
February 201874.6
March 201874.3
April 201852.8
May 201828.6
June 20185.28
July 20180.466
August 20181.73
September 20186.04
October 20189.90
November 201816.1
December 201821.3
January 201931.4
February 201955.9
March 2019132
April 2019186
May 2019175
June 2019141
July 201988.6
August 201953.4
September 201921.2
October 20199.94
November 20198.06
December 201935.9
January 202068.2
February 2020112
March 2020190
April 2020255
May 2020238
June 2020197
July 2020145
August 202093.6
September 202056.3
October 202036.6
November 202032.0
December 202025.6
January 202124.2
February 202121.8
March 202111.0
April 20210.633
May 20210.085
June 20210.059
July 20211.70
August 202120.8
September 202144.4
October 202137.8
November 202137.3
December 202128.8
January 202238.2
February 202242.8
March 202233.1
April 202218.2
May 20222.87
June 20220.040
July 20220.658
August 202224.5
September 2022111
October 2022155
November 2022213
December 2022253
January 2023359
February 2023458
March 2023559
April 2023647
May 2023639
June 2023601
July 2023546
August 2023492
September 2023451
October 2023423
November 2023413
December 2023406
January 2024406
February 2024426
March 2024444
April 2024451
May 2024433
June 2024392
July 2024344
August 2024294
September 2024250
October 2024219
November 2024208
December 2024201
January 2025198
February 2025198
March 2025184
April 2025163
May 2025133
June 202599.0
July 202558.3
August 202527.4
September 20258.99
October 202512.3
November 202514.5
December 202515.2
January 202620.0
February 202627.7
March 202626.0
April 202615.4
May 20263.34
June 20260.413
July 20260.270
August 20261.19

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 12.010203040Mm³123456789101112Month1991–2020 average 1: 21.7 Mm³1991–2020 average 2: 31.1 Mm³1991–2020 average 3: 39.3 Mm³1991–2020 average 4: 39.7 Mm³1991–2020 average 5: 33.2 Mm³1991–2020 average 6: 25.0 Mm³1991–2020 average 7: 20.3 Mm³1991–2020 average 8: 13.1 Mm³1991–2020 average 9: 11.5 Mm³1991–2020 average 10: 13.5 Mm³1991–2020 average 11: 15.2 Mm³1991–2020 average 12: 17.2 Mm³Most recent 12 months 1: 20.0 Mm³Most recent 12 months 2: 27.7 Mm³Most recent 12 months 3: 26.0 Mm³Most recent 12 months 4: 15.4 Mm³Most recent 12 months 5: 3.34 Mm³Most recent 12 months 6: 0.413 Mm³Most recent 12 months 7: 0.270 Mm³Most recent 12 months 8: 1.19 Mm³Most recent 12 months 9: 8.99 Mm³Most recent 12 months 10: 12.3 Mm³Most recent 12 months 11: 14.5 Mm³Most recent 12 months 12: 15.2 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)
Jan21.720.0
Feb31.127.7
Mar39.326.0
Apr39.715.4
May33.23.34
Jun25.00.413
Jul20.30.270
Aug13.11.19
Sep11.58.99
Oct13.512.3
Nov15.214.5
Dec17.215.2

Rate and persistence

-2.18 Mm³
Mean drawdown per month over 12 months
0 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

San Carlos Reservoir At Coolidge Dam, AZ
Gauge location
San Carlos Reservoir At Coolidge Dam, AZSan Carlos Reservoir At Coolidge Dam, AZ — 1.19 Mm³San Carlos Reservoir At Coolidge Dam, AZ — 1.19 Mm³

Where this comes from

467 monthly observations 1987–2026 Mm³
Spatially aggregatedHigh confidenceAugust 2026

Source: USGS — National Water Information System, 09469000. 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.

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