Arrowrock Res — storage

Storage now, against this reservoir's own record

215.00 Mm³

Stored, September 1986

100th

Percentile among 69 Seps on record

+279.2%

Change over the 12 months to 1986-09

Storage in September 1986 was higher than almost every other Sep on record, ranked against 69 other Seps held for this reservoir. It is the highest in the held record for this month.

Storage, 1917–1986

Monthly mean storage

828 monthly values, 1917 to 1986

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
Period	Arrowrock Res At Arrowrock Dam ID (Mm³)
October 1917	6.32
November 1917	19.2
December 1917	51.4
January 1918	132
February 1918	135
March 1918	176
April 1918	303
May 1918	329
June 1918	347
July 1918	275
August 1918	148
September 1918	51.0
October 1918	43.8
November 1918	90.5
December 1918	106
January 1919	91.6
February 1919	98.1
March 1919	94.2
April 1919	163
May 1919	299
June 1919	330
July 1919	203
August 1919	50.9
September 1919	1.88
October 1919	12.2
November 1919	26.3
December 1919	31.1
January 1920	60.2
February 1920	56.8
March 1920	46.8
April 1920	93.4
May 1920	255
June 1920	343
July 1920	270
August 1920	96.3
September 1920	3.25
October 1920	12.6
November 1920	29.9
December 1920	39.6
January 1921	105
February 1921	153
March 1921	244
April 1921	285
May 1921	339
June 1921	345
July 1921	314
August 1921	180
September 1921	54.7
October 1921	19.3
November 1921	26.0
December 1921	54.3
January 1922	103
February 1922	145
March 1922	133
April 1922	209
May 1922	302
June 1922	345
July 1922	294
August 1922	138
September 1922	16.1
October 1922	2.27
November 1922	22.5
December 1922	20.3
January 1923	50.2
February 1923	64.3
March 1923	55.9
April 1923	143
May 1923	267
June 1923	346
July 1923	319
August 1923	184
September 1923	54.0
October 1923	13.2
November 1923	26.2
December 1923	22.4
January 1924	53.4
February 1924	64.8
March 1924	45.1
April 1924	88.9
May 1924	121
June 1924	85.6
July 1924	15.2
August 1924	1.45
September 1924	0
October 1924	0.808
November 1924	21.7
December 1924	20.2
January 1925	53.6
February 1925	107
March 1925	135
April 1925	309
May 1925	345
June 1925	347
July 1925	305
August 1925	166
September 1925	47.9
October 1925	14.6
November 1925	24.1
December 1925	16.1
January 1926	35.3
February 1926	58.2
March 1926	89.0
April 1926	205
May 1926	291
June 1926	258
July 1926	138
August 1926	44.6
September 1926	9.19
October 1926	2.47
November 1926	18.0
December 1926	60.4
January 1927	109
February 1927	138
March 1927	182
April 1927	222
May 1927	284
June 1927	330
July 1927	332
August 1927	220
September 1927	86.7
October 1927	22.4
November 1927	86.8
December 1927	203
January 1928	259
February 1928	284
March 1928	303
April 1928	314
May 1928	345
June 1928	343
July 1928	274
August 1928	151
September 1928	40.8
October 1928	4.03
November 1928	21.2
December 1928	30.1
January 1929	81.8
February 1929	119
March 1929	131
April 1929	184
May 1929	275
June 1929	340
July 1929	270
August 1929	116
September 1929	15.6
October 1929	5.57
November 1929	14.5
December 1929	16.2
January 1930	42.3
February 1930	69.0
March 1930	84.7
April 1930	199
May 1930	306
June 1930	338
July 1930	237
August 1930	103
September 1930	25.4
October 1930	18.4
November 1930	30.9
December 1930	24.4
January 1931	57.9
February 1931	96.8
March 1931	119
April 1931	183
May 1931	194
June 1931	155
July 1931	49.2
August 1931	8.37
September 1931	0.029
October 1931	0.495
November 1931	9.97
December 1931	23.5
January 1932	38.8
February 1932	23.9
March 1932	33.2
April 1932	194
May 1932	337
June 1932	345
July 1932	306
August 1932	170
September 1932	49.2
October 1932	14.5
November 1932	38.6
December 1932	71.5
January 1933	48.9
February 1933	74.2
March 1933	53.1
April 1933	72.8
May 1933	196
June 1933	344
July 1933	284
August 1933	139
September 1933	34.5
October 1933	8.19
November 1933	25.2
December 1933	13.7
January 1934	47.9
February 1934	94.0
March 1934	165
April 1934	307
May 1934	323
June 1934	273
July 1934	153
August 1934	56.6
September 1934	17.5
October 1934	4.96
November 1934	22.8
December 1934	14.5
January 1935	41.2
February 1935	69.6
March 1935	94.8
April 1935	189
May 1935	339
June 1935	348
July 1935	276
August 1935	144
September 1935	40.3
October 1935	7.86
November 1935	16.4
December 1935	19.6
January 1936	41.3
February 1936	68.1
March 1936	103
April 1936	231
May 1936	339
June 1936	346
July 1936	248
August 1936	124
September 1936	33.0
October 1936	10.5
November 1936	47.6
December 1936	51.2
January 1937	44.3
February 1937	84.9
March 1937	100
April 1937	184
May 1937	307
June 1937	348
July 1937	247
August 1937	102
September 1937	24.8
October 1937	3.81
November 1937	25.3
December 1937	62.6
January 1938	145
February 1938	195
March 1938	265
April 1938	285
May 1938	332
June 1938	368
July 1938	351
August 1938	241
September 1938	103
October 1938	40.2
November 1938	95.4
December 1938	137
January 1939	184
February 1939	231
March 1939	253
April 1939	344
May 1939	368
June 1939	348
July 1939	247
August 1939	119
September 1939	37.2
October 1939	20.5
November 1939	31.8
December 1939	26.8
January 1940	74.2
February 1940	117
March 1940	203
April 1940	357
May 1940	365
June 1940	360
July 1940	259
August 1940	129
September 1940	56.3
October 1940	55.3
November 1940	94.9
December 1940	100
January 1941	149
February 1941	192
March 1941	241
April 1941	298
May 1941	344
June 1941	366
July 1941	297
August 1941	170
September 1941	72.7
October 1941	21.3
November 1941	62.6
December 1941	130
January 1942	212
February 1942	267
March 1942	299
April 1942	351
May 1942	345
June 1942	368
July 1942	323
August 1942	177
September 1942	56.7
October 1942	17.1
November 1942	53.4
December 1942	77.0
January 1943	155
February 1943	103
March 1943	146
April 1943	268
May 1943	327
June 1943	362
July 1943	367
August 1943	283
September 1943	132
October 1943	59.4
November 1943	117
December 1943	140
January 1944	192
February 1944	231
March 1944	247
April 1944	327
May 1944	364
June 1944	367
July 1944	295
August 1944	144
September 1944	34.2
October 1944	13.3
November 1944	57.9
December 1944	51.0
January 1945	95.8
February 1945	154
March 1945	185
April 1945	282
May 1945	356
June 1945	370
July 1945	325
August 1945	178
September 1945	53.1
October 1945	23.8
November 1945	57.6
December 1945	54.4
January 1946	118
February 1946	159
March 1946	215
April 1946	305
May 1946	332
June 1946	359
July 1946	351
August 1946	244
September 1946	123
October 1946	96.1
November 1946	138
December 1946	182
January 1947	249
February 1947	292
March 1947	315
April 1947	320
May 1947	368
June 1947	366
July 1947	315
August 1947	254
September 1947	160
October 1947	65.8
November 1947	72.9
December 1947	111
January 1948	152
February 1948	190
March 1948	201
April 1948	280
May 1948	364
June 1948	368
July 1948	312
August 1948	222
September 1948	136
October 1948	62.0
November 1948	80.7
December 1948	92.4
January 1949	126
February 1949	169
March 1949	230
April 1949	145
May 1949	320
June 1949	359
July 1949	277
August 1949	214
September 1949	87.1
October 1949	47.7
November 1949	61.9
December 1949	54.3
January 1950	87.0
February 1950	130
March 1950	172
April 1950	182
May 1950	184
June 1950	340
July 1950	351
August 1950	264
September 1950	66.5
October 1950	10.6
November 1950	35.9
December 1950	84.3
January 1951	165
February 1951	248
March 1951	244
April 1951	227
May 1951	281
June 1951	343
July 1951	332
August 1951	197
September 1951	82.6
October 1951	81.1
November 1951	195
December 1951	308
January 1952	286
February 1952	247
March 1952	99.6
April 1952	50.8
May 1952	108
June 1952	330
July 1952	320
August 1952	182
September 1952	61.1
October 1952	41.8
November 1952	96.3
December 1952	165
January 1953	261
February 1953	344
March 1953	323
April 1953	255
May 1953	297
June 1953	323
July 1953	340
August 1953	227
September 1953	106
October 1953	27.3
November 1953	69.8
December 1953	142
January 1954	245
February 1954	322
March 1954	287
April 1954	265
May 1954	279
June 1954	330
July 1954	326
August 1954	194
September 1954	57.3
October 1954	24.2
November 1954	62.7
December 1954	112
January 1955	172
February 1955	233
March 1955	261
April 1955	287
May 1955	355
June 1955	277
July 1955	90.8
August 1955	124
September 1955	38.6
October 1955	23.4
November 1955	70.4
December 1955	187
January 1956	333
February 1956	313
March 1956	285
April 1956	177
May 1956	220
June 1956	353
July 1956	310
August 1956	127
September 1956	23.6
October 1956	42.6
November 1956	119
December 1956	249
January 1957	293
February 1957	334
March 1957	345
April 1957	337
May 1957	281
June 1957	345
July 1957	283
August 1957	110
September 1957	30.2
October 1957	12.2
November 1957	83.3
December 1957	183
January 1958	265
February 1958	286
March 1958	193
April 1958	159
May 1958	218
June 1958	352
July 1958	294
August 1958	119
September 1958	50.9
October 1958	67.8
November 1958	101
December 1958	184
January 1959	258
February 1959	328
March 1959	338
April 1959	343
May 1959	327
June 1959	333
July 1959	236
August 1959	44.4
September 1959	12.6
October 1959	84.5
November 1959	152
December 1959	224
January 1960	272
February 1960	275
March 1960	290
April 1960	348
May 1960	326
June 1960	347
July 1960	216
August 1960	34.7
September 1960	16.3
October 1960	7.13
November 1960	48.9
December 1960	122
January 1961	194
February 1961	277
March 1961	352
April 1961	335
May 1961	83.6
June 1961	60.3
July 1961	13.7
August 1961	5.03
September 1961	3.69
October 1961	38.5
November 1961	101
December 1961	191
January 1962	254
February 1962	299
March 1962	301
April 1962	338
May 1962	233
June 1962	282
July 1962	264
August 1962	55.8
September 1962	4.46
October 1962	27.1
November 1962	123
December 1962	231
January 1963	289
February 1963	339
March 1963	339
April 1963	353
May 1963	349
June 1963	357
July 1963	280
August 1963	70.8
September 1963	11.7
October 1963	83.4
November 1963	155
December 1963	244
January 1964	331
February 1964	340
March 1964	338
April 1964	344
May 1964	306
June 1964	351
July 1964	294
August 1964	107
September 1964	20.5
October 1964	53.8
November 1964	99.5
December 1964	190
January 1965	343
February 1965	345
March 1965	222
April 1965	147
May 1965	326
June 1965	347
July 1965	350
August 1965	227
September 1965	161
October 1965	227
November 1965	275
December 1965	323
January 1966	332
February 1966	328
March 1966	341
April 1966	349
May 1966	301
June 1966	261
July 1966	104
August 1966	10.6
September 1966	21.2
October 1966	53.6
November 1966	110
December 1966	133
January 1967	150
February 1967	192
March 1967	275
April 1967	297
May 1967	251
June 1967	320
July 1967	253
August 1967	48.7
September 1967	5.28
October 1967	34.1
November 1967	98.6
December 1967	174
January 1968	242
February 1968	313
March 1968	347
April 1968	319
May 1968	130
June 1968	97.5
July 1968	23.5
August 1968	5.58
September 1968	4.94
October 1968	25.7
November 1968	108
December 1968	195
January 1969	288
February 1969	314
March 1969	135
April 1969	225
May 1969	348
June 1969	352
July 1969	270
August 1969	82.0
September 1969	6.96
October 1969	24.8
November 1969	92.4
December 1969	158
January 1970	247
February 1970	341
March 1970	343
April 1970	345
May 1970	344
June 1970	340
July 1970	326
August 1970	141
September 1970	18.2
October 1970	80.3
November 1970	148
December 1970	268
January 1971	343
February 1971	344
March 1971	269
April 1971	269
May 1971	331
June 1971	342
July 1971	346
August 1971	201
September 1971	51.5
October 1971	119
November 1971	216
December 1971	312
January 1972	341
February 1972	311
March 1972	261
April 1972	217
May 1972	238
June 1972	345
July 1972	312
August 1972	125
September 1972	18.6
October 1972	74.2
November 1972	141
December 1972	259
January 1973	342
February 1973	342
March 1973	343
April 1973	335
May 1973	321
June 1973	273
July 1973	127
August 1973	12.1
September 1973	8.01
October 1973	47.9
November 1973	102
December 1973	167
January 1974	280
February 1974	342
March 1974	292
April 1974	317
May 1974	301
June 1974	341
July 1974	316
August 1974	181
September 1974	50.3
October 1974	99.6
November 1974	132
December 1974	202
January 1975	310
February 1975	344
March 1975	344
April 1975	231
May 1975	70.2
June 1975	142
July 1975	253
August 1975	169
September 1975	50.7
October 1975	92.3
November 1975	164
December 1975	275
January 1976	343
February 1976	342
March 1976	315
April 1976	319
May 1976	249
June 1976	313
July 1976	256
August 1976	107
September 1976	13.2
October 1976	52.3
November 1976	109
December 1976	157
January 1977	213
February 1977	254
March 1977	180
April 1977	66.0
May 1977	15.5
June 1977	11.3
July 1977	18.6
August 1977	17.0
September 1977	5.08
October 1977	25.0
November 1977	67.0
December 1977	139
January 1978	195
February 1978	197
March 1978	247
April 1978	307
May 1978	169
June 1978	174
July 1978	233
August 1978	109
September 1978	41.7
October 1978	95.0
November 1978	144
December 1978	196
January 1979	250
February 1979	315
March 1979	345
April 1979	344
May 1979	273
June 1979	257
July 1979	125
August 1979	39.8
September 1979	49.4
October 1979	64.0
November 1979	120
December 1979	172
January 1980	233
February 1980	305
March 1980	345
April 1980	348
May 1980	351
June 1980	351
July 1980	319
August 1980	172
September 1980	150
October 1980	92.9
November 1980	83.4
December 1980	149
January 1981	224
February 1981	301
March 1981	353
April 1981	353
May 1981	342
June 1981	348
July 1981	230
August 1981	56.8
September 1981	44.8
October 1981	52.5
November 1981	107
December 1981	188
January 1982	266
February 1982	263
March 1982	231
April 1982	144
May 1982	238
June 1982	336
July 1982	346
August 1982	232
September 1982	126
October 1982	202
November 1982	199
December 1982	132
January 1983	139
February 1983	103
March 1983	152
April 1983	150
May 1983	221
June 1983	351
July 1983	332
August 1983	175
September 1983	51.4
October 1983	66.8
November 1983	193
December 1983	309
January 1984	137
February 1984	89.9
March 1984	117
April 1984	211
May 1984	245
June 1984	326
July 1984	329
August 1984	170
September 1984	140
October 1984	184
November 1984	175
December 1984	169
January 1985	176
February 1985	230
March 1985	295
April 1985	273
May 1985	296
June 1985	323
July 1985	222
August 1985	72.6
September 1985	56.7
October 1985	111
November 1985	189
December 1985	227
January 1986	267
February 1986	346
March 1986	320
April 1986	259
May 1986	228
June 1986	343
July 1986	276
August 1986	210
September 1986	215

Rate and persistence

+13.19 Mm³

Mean change per month over 12 months

2 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

Arrowrock Res At Arrowrock Dam ID

Gauge location

Where this comes from

828 monthly observations 1917–1986 Mm³

Spatially aggregatedHigh confidenceSeptember 1986

Source: USGS — National Water Information System, 13194000. 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.