Lake Kachess Water Level

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About

This data is taken from the U.S. Bureau of Reclamation. They have a decent chart showing the amount of water in Kachess reservoir here (and shown to the right). They have complete source data for download here.

Unfortunately it has a few deficiencies:

  • Units - The chart shows the volume of water in the reservoir. As a recreational lake user, what I care about is how far it is below full.
  • Context - The chart shows the average water level, but that averages good years and bad. What I care about is what type of year it is and where is it likely to go.

This mini website attempts to help answer those questions and give some insight into the lake level. It's almost certainly overkill analysis for what any normal person would care about, but I needed to refresh some technical skills, and this was an interesting data set to play with.

Data Sources

Regression

The USBR has a metric called "kac_fb" which is "Reservoir Surface Elevation, feet". This is almost exactly what we want. Unfortunately the data begins in 6/3/2017. So what I wanted to do is figure out the relationship between surface elevation and "kac_af" - Reservoir Water Storage (volume), which we have for the entire period.

A simple and accurate way to figure out this relationship is with a regression analysis. Explaining how that works is beyond the scope of this site, but for those who are interested, here are the results of that analysis.

The equation relating surface elevation to lake volume

kac_fb = 2,193 + 0.0004*kac_af + -0.00000000038*kac_af^2


feetdown = -1 * (max(kac_fb) - kac_fb)

Regression Statistics


OLS Regression Results
Dep. Variable: kac_fb R-squared: 1.000
Model: OLS Adj. R-squared: 1.000
Method: Least Squares F-statistic: 2.886e+07
Date: Wed, 17 Jul 2024 Prob (F-statistic): 0.00
Time: 12:00:46 Log-Likelihood: -9005.2
No. Observations: 27222 AIC: 1.802e+04
Df Residuals: 27219 BIC: 1.804e+04
Df Model: 2
Covariance Type: nonrobust
coef std err t P>|t| [0.025 0.975]
const 2193.0089 0.011 1.95e+05 0.000 2192.987 2193.031
kac_af 0.0004 1.63e-07 2318.156 0.000 0.000 0.000
kac_af_squared -3.802e-10 5.54e-13 -686.359 0.000 -3.81e-10 -3.79e-10
Omnibus: 67881.047 Durbin-Watson: 0.643
Prob(Omnibus): 0.000 Jarque-Bera (JB): 6311336565.918
Skew: -26.317 Prob(JB): 0.00
Kurtosis: 2361.295 Cond. No. 1.85e+11


Notes:
[1] Standard Errors assume that the covariance matrix of the errors is correctly specified.
[2] The condition number is large, 1.85e+11. This might indicate that there are
strong multicollinearity or other numerical problems.

Regression Error: Actual vs. Predicted

Regression Error: Feet Down vs. Date

Regression Error: Residuals vs. kac_af

About the Raw Data

Field Description Data Start Data End Number Records
kac_af Reservoir Water Storage, acre-feet 1/1/1950 7/16/2024 27,225
kac_fb Reservoir Water Surface Elevation, feet 1/1/1950 7/16/2024 27,222
fb_predict Predicted surface elevation (Added) 1/1/1950 7/16/2024 27,225
fb_predict_err Prediction error (Added) 1/1/1950 7/16/2024 27,222
feetdown Feet down from maximum (Added) 1/1/1950 7/16/2024 27,225
kac_qu Estimated Average Unregulated Flow, cfs 1/1/1950 7/16/2024 27,185
kac_qd Average Stream Discharge, cfs 1/1/1950 7/16/2024 27,186
kac_mm Average Air Temperature, degF 4/1/1978 7/16/2024 10,365
kac_pc Cummulative Precipitation, inches 5/31/1984 7/16/2024 14,573
kac_pp Daily Total Precipitation, inches 1/1/1978 7/16/2024 16,973

Highest / Lowest Lake Levels Per Year

Maximum Lake Level Minimum Lake Level
Year Date Feetdown (ft) Volume (acre-feet) Date Feetdown Volume
1950 7/2/1950 -0.7 240,890 10/4/1950 -27.4 128,810
1951 6/15/1951 -0.8 240,840 8/18/1951 -29.5 121,320
1952 5/29/1952 -0.8 240,710 10/10/1952 -38.6 90,750
1953 6/18/1953 -0.6 241,750 1/1/1953 -36.7 96,810
1954 6/26/1954 -0.8 240,340 10/11/1954 -17.6 165,350
1955 6/13/1955 -0.3 243,030 10/3/1955 -21.1 151,750
1956 7/3/1956 -0.8 240,340 4/10/1956 -25.0 137,340
1957 5/9/1957 -0.0 244,720 10/15/1957 -43.1 76,450
1958 6/11/1958 -5.1 219,440 1/1/1958 -35.7 100,230
1959 6/23/1959 -0.5 242,250 9/18/1959 -18.0 164,050
1960 6/17/1960 -0.4 242,800 10/15/1960 -27.7 127,620
1961 6/19/1961 -0.4 242,850 10/10/1961 -29.2 122,140
1962 6/18/1962 -0.3 243,120 10/9/1962 -28.6 124,400
1963 5/23/1963 -0.1 243,990 10/10/1963 -38.1 92,170
1964 7/8/1964 -0.0 244,580 1/1/1964 -30.4 118,110
1965 6/14/1965 -0.4 242,390 9/28/1965 -26.5 132,000
1966 6/13/1966 -1.2 238,440 10/14/1966 -30.2 118,820
1967 6/26/1967 -0.3 243,030 10/12/1967 -25.6 135,160
1968 2/28/1968 -2.1 234,230 10/11/1968 -26.9 130,500
1969 6/10/1969 -0.1 244,260 12/31/1969 -19.4 158,500
1970 6/24/1970 -0.8 240,660 10/15/1970 -28.1 126,250
1971 7/20/1971 -0.6 241,620 12/31/1971 -22.2 147,810
1972 8/8/1972 -0.7 241,220 1/6/1972 -22.2 147,540
1973 1/1/1973 -9.0 201,510 9/20/1973 -59.5 27,810
1974 7/19/1974 -0.7 241,210 1/1/1974 -49.0 58,190
1975 7/16/1975 -1.3 238,250 1/1/1975 -31.1 115,600
1976 6/21/1976 -0.4 242,800 10/21/1976 -18.7 161,230
1977 5/4/1977 -1.7 236,040 9/28/1977 -41.5 81,330
1978 6/6/1978 -0.0 244,672 10/13/1978 -20.7 153,600
1979 5/16/1979 -0.3 243,074 11/1/1979 -61.7 21,651
1980 6/27/1980 -14.4 178,295 1/1/1980 -48.0 61,373
1981 4/30/1981 -0.8 240,391 10/5/1981 -33.8 106,662
1982 5/17/1982 -1.1 239,127 1/1/1982 -27.1 129,629
1983 6/1/1983 -1.2 238,633 11/1/1983 -30.7 116,980
1984 5/31/1984 -1.3 238,212 10/13/1984 -29.9 119,733
1985 6/20/1985 -1.4 237,665 10/7/1985 -51.1 52,190
1986 6/7/1986 -5.1 219,489 10/25/1986 -62.0 21,060
1987 6/11/1987 -16.0 171,986 10/14/1987 -61.7 21,700
1988 6/29/1988 -17.3 166,492 10/13/1988 -61.2 23,280
1989 6/6/1989 -10.2 196,213 10/18/1989 -47.4 63,190
1990 6/10/1990 -0.7 241,342 1/1/1990 -32.6 110,608
1991 5/24/1991 -1.4 237,755 10/20/1991 -39.0 89,260
1992 5/21/1992 -4.6 221,750 10/19/1992 -60.9 24,030
1993 5/22/1993 -25.1 136,910 10/31/1993 -62.6 19,360
1994 5/13/1994 -33.9 106,040 10/18/1994 -62.7 18,920
1995 8/2/1995 -4.8 220,640 1/1/1995 -47.6 62,420
1996 2/12/1996 -1.7 235,945 9/24/1996 -58.8 29,750
1997 7/10/1997 -0.9 239,935 1/1/1997 -43.1 76,320
1998 5/25/1998 -0.8 240,754 10/22/1998 -42.6 77,902
1999 8/4/1999 -1.0 239,567 1/1/1999 -28.5 124,661
2000 7/10/2000 -1.1 238,935 10/17/2000 -34.2 105,120
2001 5/27/2001 -17.0 168,009 10/10/2001 -62.6 19,355
2002 7/7/2002 -0.9 240,295 1/1/2002 -47.7 62,150
2003 6/18/2003 -1.4 237,710 10/16/2003 -53.0 46,396
2004 6/22/2004 -18.1 163,570 10/15/2004 -52.3 48,646
2005 5/25/2005 -17.4 166,330 9/30/2005 -60.6 24,788
2006 7/22/2006 -14.4 178,380 1/1/2006 -50.7 53,138
2007 6/19/2007 -1.1 239,070 10/15/2007 -34.0 105,760
2008 7/3/2008 -1.2 238,620 1/1/2008 -25.8 134,334
2009 6/20/2009 -1.2 238,620 10/16/2009 -36.1 98,840
2010 7/11/2010 -2.9 229,870 10/19/2010 -30.3 118,549
2011 7/25/2011 -1.1 238,800 10/17/2011 -26.4 132,114
2012 7/8/2012 -1.2 238,710 10/15/2012 -25.6 135,314
2013 6/20/2013 -1.1 238,935 10/11/2013 -26.4 132,342
2014 6/2/2014 -1.2 238,755 10/16/2014 -31.7 113,607
2015 4/6/2015 -1.1 238,845 10/29/2015 -56.8 35,576
2016 5/19/2016 -1.1 238,845 10/14/2016 -40.5 84,532
2017 6/15/2017 -1.1 238,890 10/17/2017 -36.6 97,300
2018 6/19/2018 -1.1 238,845 10/15/2018 -38.1 92,428
2019 6/17/2019 -5.4 217,852 10/15/2019 -56.7 35,772
2020 6/25/2020 -4.2 223,620 1/1/2020 -46.0 67,417
2021 6/7/2021 -1.6 236,350 10/21/2021 -33.9 106,293
2022 6/20/2022 -1.2 238,439 10/23/2022 -34.1 105,366
2023 6/27/2023 -8.7 203,026 11/1/2023 -62.2 20,391
2024 6/16/2024 -24.8 138,098 1/1/2024 -52.7 47,264