Kachess Lake — storage

Storage now, against this reservoir's own record

123.52 Mm³

Stored, September 2026

33rd

Percentile among 121 Seps on record

-19.9%

Against the Sep 1991–2020 average

+133.0%

Change over the 12 months to 2026-09

Storage in September 2026 was around the middle of the Sep record, ranked against 121 other Seps held for this reservoir.

Storage, 1905–2026

Monthly mean storage

1,452 monthly values, 1905 to 2026

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 1,452 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,452 would be longer than this page and unusable with a screen reader.
Period	Kachess Lake (Mm³)
October 1905	7.85
April 1906	15.9
October 1906	9.17
April 1907	8.59
October 1907	3.53
April 1908	10.7
October 1908	2.28
April 1909	6.62
November 1909	12.9
May 1910	16.3
November 1910	11.4
May 1911	14.2
November 1911	0
May 1912	104
November 1912	76.6
May 1913	54.6
November 1913	63.5
May 1914	137
November 1914	34.4
May 1915	109
November 1915	35.5
May 1916	166
December 1916	164
June 1917	260
December 1917	147
June 1918	282
December 1918	176
June 1919	251
December 1919	148
June 1920	273
December 1920	161
June 1921	264
December 1921	191
June 1922	281
December 1922	50.8
June 1923	248
January 1924	135
July 1924	195
January 1925	100.0
July 1925	284
January 1926	166
July 1926	162
January 1927	88.5
July 1927	262
January 1928	190
July 1928	262
January 1929	174
July 1929	261
January 1930	185
July 1930	194
February 1931	84.8
August 1931	80.5
February 1932	77.1
August 1932	216
February 1933	205
August 1933	239
February 1934	207
August 1934	199
February 1935	185
August 1935	132
February 1936	137
August 1936	130
February 1937	116
August 1937	163
March 1938	204
September 1938	182
March 1939	214
September 1939	135
March 1940	190
September 1940	138
March 1941	169
September 1941	94.0
March 1942	158
September 1942	97.2
March 1943	143
September 1943	224
March 1944	254
September 1944	84.6
April 1945	165
October 1945	165
April 1946	255
October 1946	157
April 1947	275
October 1947	181
April 1948	251
October 1948	206
April 1949	225
October 1949	124
April 1950	222
October 1950	168
April 1951	233
October 1951	161
May 1952	280
November 1952	114
May 1953	266
November 1953	185
May 1954	254
November 1954	215
May 1955	256
November 1955	235
May 1956	239
November 1956	198
May 1957	293
November 1957	100
May 1958	236
November 1958	164
June 1959	296
December 1959	262
June 1960	297
December 1960	198
June 1961	294
December 1961	180
June 1962	298
December 1962	208
June 1963	285
December 1963	139
June 1964	291
December 1964	227
June 1965	296
December 1965	185
July 1966	259
January 1967	215
July 1967	279
January 1968	247
July 1968	250
January 1969	232
July 1969	270
January 1970	199
July 1970	273
January 1971	197
July 1971	295
January 1972	187
July 1972	292
January 1973	241
August 1973	85.0
February 1974	127
August 1974	216
February 1975	183
August 1975	271
February 1976	251
August 1976	291
February 1977	244
August 1977	210
February 1978	237
August 1978	247
February 1979	227
August 1979	112
February 1980	90.5
September 1980	134
March 1981	261
September 1981	165
March 1982	240
September 1982	195
March 1983	266
September 1983	197
March 1984	260
September 1984	184
March 1985	195
September 1985	92.6
March 1986	179
September 1986	39.2
March 1987	101
October 1987	27.4
April 1988	112
October 1988	34.0
April 1989	167
October 1989	85.6
April 1990	241
October 1990	161
April 1991	273
October 1991	123
April 1992	245
October 1992	30.6
April 1993	117
October 1993	24.5
April 1994	106
November 1994	41.8
May 1995	217
November 1995	136
May 1996	268
November 1996	63.3
May 1997	263
November 1997	176
May 1998	290
November 1998	106
May 1999	246
November 1999	172
May 2000	286
November 2000	135
May 2001	200
December 2001	68.5
June 2002	274
December 2002	139
June 2003	290
December 2003	107
June 2004	200
December 2004	103
June 2005	193
December 2005	55.1
June 2006	203
December 2006	155
June 2007	294
December 2007	159
June 2008	286
January 2009	241
July 2009	289
January 2010	168
July 2010	281
January 2011	210
July 2011	294
January 2012	189
July 2012	294
January 2013	216
July 2013	292
January 2014	210
July 2014	289
January 2015	232
July 2015	213
February 2016	165
August 2016	236
February 2017	156
August 2017	257
February 2018	219
August 2018	246
February 2019	184
August 2019	178
February 2020	153
August 2020	236
February 2021	195
August 2021	262
February 2022	230
August 2022	273
March 2023	177
September 2023	81.0
March 2024	94.7
September 2024	79.0
March 2025	94.7
September 2025	53.0
March 2026	197
September 2026	124

The reservoir's year

Seasonal storage profile

Each calendar month's reference average, against the most recent year

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
Period	1991–2020 average (Mm³)	Most recent 12 months (Mm³)
Jan	161	149
Feb	181	170
Mar	197	197
Apr	219	241
May	247	261
Jun	259	258
Jul	245	235
Aug	212	190
Sep	154	124
Oct	106	29.2
Nov	118	42.9
Dec	139	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.

Water level

Monthly mean water surface elevation

1,356 monthly values

An elevation above a datum, not a depth of water and not a distance below the crest. Levels at different reservoirs are measured against different datums and must not be read against one another; this line is comparable only with its own history. Elevation and volume are not proportional either — a metre near the bottom of a reservoir holds far less water than a metre near the top, because the surface area grows with height.

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 1,356 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,356 would be longer than this page and unusable with a screen reader.
Period	Kachess Lake (m)
1912.75	676
1913.25	671
1913.6666666666667	678
1914.1666666666667	675
1914.6666666666667	673
1915.0833333333333	672
1915.5833333333333	671
1917.0833333333333	683
1917.5	688
1918	686
1918.5	688
1918.9166666666667	683
1919.4166666666667	687
1919.9166666666667	681
1920.3333333333333	687
1920.8333333333333	681
1921.3333333333333	687
1921.75	679
1922.25	686
1922.75	672
1923.1666666666667	678
1923.6666666666667	679
1924.1666666666667	683
1924.5833333333333	677
1925.0833333333333	679
1925.5833333333333	686
1926	682
1926.5	682
1927	676
1927.4166666666667	686
1927.9166666666667	684
1928.4166666666667	689
1928.8333333333333	681
1929.3333333333333	686
1929.8333333333333	682
1930.25	687
1930.75	673
1931.25	680
1931.6666666666667	672
1932.1666666666667	679
1932.6666666666667	682
1933.0833333333333	684
1933.5833333333333	686
1934.0833333333333	684
1934.5	686
1935	683
1935.5	684
1935.9166666666667	678
1936.4166666666667	683
1936.9166666666667	677
1937.3333333333333	683
1937.8333333333333	679
1938.3333333333333	688
1938.75	680
1939.25	685
1939.75	679
1940.1666666666667	683
1940.6666666666667	680
1941.1666666666667	682
1941.5833333333333	677
1942.0833333333333	681
1942.5833333333333	681
1943.0833333333333	680
1943.5	689
1944	686
1944.5	686
1944.9166666666667	676
1945.4166666666667	687
1945.9166666666667	684
1946.3333333333333	688
1946.8333333333333	682
1947.3333333333333	689
1947.75	683
1948.25	687
1948.75	684
1949.1666666666667	685
1949.6666666666667	679
1950.1666666666667	686
1950.5833333333333	687
1951.0833333333333	686
1951.5833333333333	682
1952	684
1952.5	687
1953	680
1953.4166666666667	690
1953.9166666666667	685
1954.4166666666667	689
1954.8333333333333	685
1955.3333333333333	687
1955.8333333333333	686
1956.25	683
1956.75	683
1957.25	688
1957.6666666666667	680
1958.1666666666667	682
1958.6666666666667	681
1959.0833333333333	686
1959.5833333333333	686
1960.0833333333333	686
1960.5	688
1961	685
1961.5	688
1961.9166666666667	683
1962.4166666666667	690
1962.9166666666667	684
1963.3333333333333	690
1963.8333333333333	679
1964.3333333333333	686
1964.75	684
1965.25	686
1965.75	682
1966.1666666666667	685
1966.6666666666667	682
1967.1666666666667	687
1967.5833333333333	685
1968.0833333333333	688
1968.5833333333333	685
1969	686
1969.5	688
1970	684
1970.4166666666667	689
1970.9166666666667	683
1971.4166666666667	689
1971.8333333333333	684
1972.3333333333333	685
1972.8333333333333	686
1973.25	686
1973.75	672
1974.25	682
1974.6666666666667	679
1975.1666666666667	684
1975.6666666666667	686
1976.0833333333333	687
1976.5833333333333	689
1977.0833333333333	687
1977.5	685
1978	686
1978.5	689
1978.9166666666667	684
1979.4166666666667	688
1979.9166666666667	673
1980.3333333333333	683
1980.8333333333333	679
1981.3333333333333	689
1981.75	680
1982.25	688
1982.75	682
1983.1666666666667	688
1983.6666666666667	684
1984.1666666666667	688
1984.5833333333333	686
1985.0833333333333	683
1985.5833333333333	682
1986	679
1986.5	682
1987	675
1987.4166666666667	684
1987.9166666666667	671
1988.4166666666667	684
1988.8333333333333	673
1989.3333333333333	685
1989.8333333333333	677
1990.25	686
1990.75	682
1991.25	688
1991.6666666666667	684
1992.1666666666667	685
1992.6666666666667	672
1993.0833333333333	675
1993.5833333333333	673
1994.0833333333333	673
1994.5	675
1995	676
1995.5	688
1995.9166666666667	685
1996.4166666666667	685
1996.9166666666667	676
1997.3333333333333	688
1997.8333333333333	682
1998.3333333333333	689
1998.8333333333333	678
1999.25	685
1999.75	682
2000.25	688
2000.6666666666667	684
2001.1666666666667	681
2001.6666666666667	672
2002.0833333333333	678
2002.5833333333333	688
2003.0833333333333	683
2003.5	688
2004	678
2004.5	683
2004.9166666666667	677
2005.4166666666667	684
2005.9166666666667	673
2006.3333333333333	682
2006.8333333333333	679
2007.3333333333333	689
2007.75	680
2008.25	684
2008.75	682
2009.1666666666667	688
2009.6666666666667	684
2010.1666666666667	684
2010.5833333333333	688
2011.0833333333333	687
2011.5833333333333	689
2012	683
2012.5	689
2013	685
2013.4166666666667	689
2013.9166666666667	684
2014.4166666666667	689
2014.8333333333333	682
2015.3333333333333	689
2015.8333333333333	675
2016.25	686
2016.75	678
2017.25	684
2017.6666666666667	683
2018.1666666666667	686
2018.6666666666667	683
2019.0833333333333	683
2019.5833333333333	683
2020.0833333333333	681
2020.5	688
2021	683
2021.5	689
2021.9166666666667	684
2022.4166666666667	689
2022.9166666666667	681
2023.3333333333333	686
2023.8333333333333	671
2024.3333333333333	680
2024.75	672
2025.25	680
2025.75	671
2026.1666666666667	684
2026.6666666666667	679

Rate and persistence

+5.88 Mm³

Mean change per month over 12 months

13 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

Kachess Lake

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 Bureau of Reclamation — Reservoir operations and Colorado River data · US Government work — public domain
How the values came to exist	Measured
Period held	1905–2026
Completeness	99.2% 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	99% of the months between 1905 and 2026 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-usbr-7186.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), Kachess Lake reservoir records, accessed 2026-10-05, hydrionis.com/reservoirs/reservoir-usbr-7186/

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 Kachess Lake 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

1,452 monthly observations 1905–2026 Mm³

Spatially aggregatedHigh confidenceSeptember 2026

Source: USBR — Reservoir operations and Colorado River data, RISE catalogue item 131227. Licence: Open.

Method: Monthly mean of the daily values published by the Bureau of Reclamation in acre-feet, converted to Mm³. Months with fewer than 20 days of record are not published rather than averaged from a partial month.

Stored as a volume and not as a share of capacity: the operator publishes what is in the reservoir but not what it holds when full, so a percentage cannot be computed without inventing the denominator.

Retrieved 1 October 2026.

Monthly mean of the daily values published by the Bureau of Reclamation in acre-feet, converted to Mm³. Months with fewer than 20 days of record are not published rather than averaged from a partial month.