Kachess Lake — storage

Storage now, against this reservoir's own record

191.04 Mm³

Stored, August 2026

41st

Percentile among 121 Augs on record

-9.9%

Against the Aug 1991–2020 average

+75.5%

Change over the 12 months to 2026-08

Storage in August 2026 was around the middle of the Aug record, ranked against 121 other Augs held for this reservoir.

Storage, 1905–2026

Monthly mean storage

1,451 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 1,451 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,451 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
November 1916	157
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
December 1923	117
June 1924	281
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
January 1931	69.4
July 1931	158
January 1932	63.7
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
February 1938	196
August 1938	231
February 1939	207
August 1939	182
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
March 1945	150
September 1945	162
March 1946	241
September 1946	184
March 1947	261
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
April 1952	241
October 1952	113
April 1953	220
October 1953	175
April 1954	230
October 1954	206
May 1955	256
November 1955	235
May 1956	239
November 1956	198
May 1957	293
November 1957	100
May 1958	236
November 1958	164
May 1959	284
November 1959	254
May 1960	289
November 1960	180
May 1961	264
November 1961	165
May 1962	282
December 1962	208
June 1963	285
December 1963	139
June 1964	291
December 1964	227
June 1965	296
December 1965	185
June 1966	288
December 1966	183
June 1967	285
December 1967	218
June 1968	280
December 1968	210
June 1969	297
January 1970	199
July 1970	273
January 1971	197
July 1971	295
January 1972	187
July 1972	292
January 1973	241
July 1973	163
January 1974	88.6
July 1974	292
January 1975	157
July 1975	290
January 1976	254
July 1976	294
January 1977	227
August 1977	210
February 1978	237
August 1978	247
February 1979	227
August 1979	112
February 1980	90.5
August 1980	170
February 1981	234
August 1981	238
February 1982	201
August 1982	240
February 1983	250
August 1983	246
February 1984	242
August 1984	239
March 1985	195
September 1985	92.6
March 1986	179
September 1986	39.2
March 1987	101
September 1987	35.5
March 1988	73.1
September 1988	44.7
March 1989	134
September 1989	131
March 1990	198
September 1990	224
March 1991	273
September 1991	204
March 1992	217
October 1992	30.6
April 1993	117
October 1993	24.5
April 1994	106
October 1994	25.1
April 1995	176
October 1995	100
April 1996	282
October 1996	41.6
April 1997	201
October 1997	158
April 1998	249
October 1998	104
April 1999	217
October 1999	164
May 2000	286
November 2000	135
May 2001	200
November 2001	45.3
May 2002	209
November 2002	136
May 2003	263
November 2003	79.9
May 2004	192
November 2004	76.0
May 2005	202
November 2005	44.4
May 2006	164
November 2006	130
May 2007	293
December 2007	159
June 2008	286
December 2008	209
June 2009	294
December 2009	156
June 2010	273
December 2010	178
June 2011	292
December 2011	173
June 2012	294
December 2012	208
June 2013	294
December 2013	193
June 2014	293
December 2014	198
July 2015	213
January 2016	141
July 2016	272
January 2017	153
July 2017	284
January 2018	189
July 2018	279
January 2019	170
July 2019	242
January 2020	104
July 2020	265
January 2021	178
July 2021	281
January 2022	212
July 2022	289
February 2023	170
August 2023	153
February 2024	78.6
August 2024	131
February 2025	75.0
August 2025	109
February 2026	170
August 2026	191

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	191
Sep	154	53.0
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

1,355 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 1,355 periods, evenly spaced across the record. Every value is in the download and the API; a table of all 1,355 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	679
1943.5	689
1944	686
1944.4166666666667	688
1944.9166666666667	676
1945.4166666666667	687
1945.8333333333333	683
1946.3333333333333	688
1946.8333333333333	682
1947.25	688
1947.75	683
1948.25	687
1948.6666666666667	684
1949.1666666666667	685
1949.6666666666667	679
1950.0833333333333	685
1950.5833333333333	687
1951.0833333333333	686
1951.5	687
1952	684
1952.5	687
1952.9166666666667	679
1953.4166666666667	690
1953.9166666666667	685
1954.3333333333333	687
1954.8333333333333	685
1955.3333333333333	687
1955.75	684
1956.25	683
1956.75	683
1957.1666666666667	687
1957.6666666666667	680
1958.1666666666667	682
1958.5833333333333	684
1959.0833333333333	686
1959.5833333333333	686
1960	685
1960.5	688
1961	685
1961.4166666666667	689
1961.9166666666667	683
1962.4166666666667	690
1962.8333333333333	682
1963.3333333333333	690
1963.8333333333333	679
1964.25	684
1964.75	684
1965.25	686
1965.6666666666667	682
1966.1666666666667	685
1966.6666666666667	682
1967.0833333333333	686
1967.5833333333333	685
1968.0833333333333	688
1968.5	687
1969	686
1969.5	688
1969.9166666666667	684
1970.4166666666667	689
1970.8333333333333	682
1971.3333333333333	686
1971.8333333333333	684
1972.25	686
1972.75	687
1973.25	686
1973.6666666666667	672
1974.1666666666667	680
1974.6666666666667	679
1975.0833333333333	683
1975.5833333333333	688
1976.0833333333333	687
1976.5	689
1977	686
1977.5	685
1977.9166666666667	684
1978.4166666666667	690
1978.9166666666667	684
1979.3333333333333	690
1979.8333333333333	671
1980.3333333333333	683
1980.75	678
1981.25	689
1981.75	680
1982.1666666666667	686
1982.6666666666667	684
1983.1666666666667	688
1983.5833333333333	687
1984.0833333333333	687
1984.5833333333333	686
1985	683
1985.5	688
1986	679
1986.4166666666667	687
1986.9166666666667	674
1987.4166666666667	684
1987.8333333333333	671
1988.3333333333333	681
1988.8333333333333	673
1989.25	682
1989.75	676
1990.25	686
1990.6666666666667	685
1991.1666666666667	688
1991.6666666666667	684
1992.0833333333333	684
1992.5833333333333	675
1993.0833333333333	675
1993.5	678
1994	672
1994.5	675
1994.9166666666667	674
1995.4166666666667	687
1995.9166666666667	685
1996.3333333333333	688
1996.8333333333333	674
1997.3333333333333	688
1997.75	681
1998.25	687
1998.75	677
1999.1666666666667	684
1999.6666666666667	686
2000.1666666666667	686
2000.5833333333333	688
2001.0833333333333	681
2001.5833333333333	676
2002	676
2002.5	689
2003	681
2003.4166666666667	689
2003.9166666666667	678
2004.4166666666667	684
2004.8333333333333	675
2005.3333333333333	684
2005.8333333333333	672
2006.25	679
2006.75	677
2007.25	688
2007.6666666666667	684
2008.1666666666667	683
2008.6666666666667	686
2009.0833333333333	687
2009.5833333333333	688
2010.0833333333333	683
2010.5	689
2011	685
2011.5	689
2011.9166666666667	682
2012.4166666666667	689
2012.9166666666667	685
2013.3333333333333	689
2013.8333333333333	682
2014.3333333333333	689
2014.75	681
2015.25	689
2015.75	673
2016.1666666666667	684
2016.6666666666667	682
2017.1666666666667	682
2017.5833333333333	687
2018.0833333333333	685
2018.5833333333333	687
2019	682
2019.5	687
2020	677
2020.4166666666667	688
2020.9166666666667	681
2021.4166666666667	689
2021.8333333333333	681
2022.3333333333333	689
2022.8333333333333	680
2023.25	683
2023.75	671
2024.25	679
2024.6666666666667	675
2025.1666666666667	677
2025.6666666666667	673
2026.0833333333333	682
2026.5833333333333	683

Rate and persistence

+6.85 Mm³

Mean change per month over 12 months

14 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	99.1% 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	2026-09-01
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 2026-09-02, 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

1,451 monthly observations 1905–2026 Mm³

Spatially aggregatedHigh confidenceAugust 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 September 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.