11441001 UNION VALLEY RESERVOIR NEAR RIVERTON, CA

LOCATION.--Lat 38°51'33", long 120°26'13", in NW 1/4 NW 1/4 sec.29, T.12 N., R.14 E., El Dorado County, Hydrologic Unit 18020129, 
  Eldorado National Forest, in valve control house near left bank at Union Valley Dam on Silver Creek, 0.7 mi upstream from Little Silver Creek, 
  and 6.6 mi north of Riverton. 
DRAINAGE AREA.--83.7 mi2. 
PERIOD OF RECORD.--October 1962 to current year. 
CHEMICAL ANALYSES.--June to September 1996.
GAGE.--Water-stage recorder. Datum of gage is sea level (levels by Sacramento Municipal Utility District). 
REMARKS.--Reservoir is formed by earthfill dam completed in December 1962; storage began May 1962. Usable capacity, 269,514 acre-ft 
  between elevations 4,645.0 ft, minimum operating level, and 4,870.0 ft, top of radial spillway gates. Dead storage, 7,921 acre-ft. Reservoir 
  receives water from the South Fork Rubicon River via Robbs Peak Powerplant (station 11429300) and from South Fork Silver Creek, since 
  April 1985, via Jones Fork Powerplant (station 11440900). Water is used for power development in the South Fork American River basin. 
  Discharge to Union Valley Powerplant (station 11441002) is shown as a line item below this table. Records, including extremes, represent total 
  contents. See schematic diagrams of Middle Fork American and Rubicon River basins and South Fork American River basin. 
COOPERATION.--Records were collected by Sacramento Municipal Utility District, under general supervision of the U.S. Geological Survey, in 
  connection with a Federal Energy Regulatory Commission project. Contents not rounded to U.S. Geological Survey standards. 
EXTREMES FOR PERIOD OF RECORD.--Maximum contents, 279,100 acre-ft, July 9, 1974, elevation, 4,870.6 ft; minimum since reservoir first 
  filled, 18,300 acre-ft, Jan. 13, 1977, elevation, 4,683.3 ft. 
EXTREMES FOR CURRENT YEAR.--Maximum contents, 276,925 acre-ft, June 4, elevation, 4,869.83 ft; minimum, 182,683 acre-ft, Oct. 31, 
  elevation, 4,833.52 ft. 
  Capacity table (elevation, in feet, and contents, in acre-feet)
  (Based on table provided by Sacramento Municipal Utility District, recomputed October 1991)
	4,680	17,675	4,780	89,926
	4,700	25,160	4,800	118,894
	4,720	35,266	4,820	154,489
	4,740	48,883	4,840	197,460
	4,760	66,841	4,870	277,435

                   RESERVOIR STORAGE (ACRE-FEET), WATER YEAR OCTOBER 1996 TO SEPTEMBER 1997

                                        DAILY OBSERVATION AT 2400 HOURS
 
DAY       OCT      NOV      DEC      JAN      FEB      MAR      APR      MAY      JUN      JUL      AUG      SEP
 
  1    204998   184061   197413   249629   225366   212076   208906   244605   275429   271508   247274   227517
  2    204011   185334   198847   260016   225624   212002   207954  e245923   276027   270593   246171   226919
  3    203292   186568   201239   251442   225211   211213   207906  e246556   276266   269357   245071   226167
  4    202454   187922   203867   245978   224360   210425   207857   247854   276925   268448   244003   225030
  5    201548   189306   211336   242583   223358   210278   207760   249463   276206   267862   243347   223923

  6    200526   190560   214010   239978   222256   209787   207614   250047   276266   267277   242556   222538
  7    199390   191109   214982   238145   220930   209542   207419   251805   276027   266810   242148   221337
  8    198588   190240   215706   236724   220066   209346   207468   253095   275788   266635   242039   220243
  9    197859   189829   216809   235282   218723   209248   207541   255067   275668   265586   241007   218446
 10    196523   189602   219533   233873   217840   209199   207516   256652   276027   265267   240546   216759
 
 11    195730   188874   223794   232391   216909   209004   208028   258017   275310   264744   239384   215081
 12    194474   188647   229918   231310   216382   208906   208466   260303   274981   264135   239303   213116
 13    193571   188239   232127   230206   215931   208906   209199   262603   275608   263325   239061   211336
 14    192878   187357   231494   228898   215331   209787   210131   263527   275997   262690   238334   209493
 15    191912   186771   229918   227855   214558   209910   211114   263498   276505   262171   238414   207857

 16    190651   186029   228167   226634   213910   209273   212175   264106   276146   261221   237904   205940
 17    190377   188692   226374   225185   213811   209542   213935   265180   276446   260446   237152   203963
 18    189738   193617   224669   223769   213389   209224   216332   265907   276356   259816   236537   201977
 19    188556   195194   222922   223153   212497   208735   220574   266664   276296   259415   236430   200526
 20    188058   196874   221950   222717   211903   208101   223050   267716   276386   257960   236483   199296
 
 21    186839   196991   221465   221720   210966   208344   225883   267569   276236   257448   236243   198353
 22    185760   199839   220523   221567   209910   208882   228011   269122   276206   256595   237340   196827
 23    185491   201263   219280   220497   209102   209591   231652   270888   276027   255632   237206   195217
 24    185827   202049   218420   219280   208808   209812   233926   272366   275429   254954   235975   193340
 25    186096   201405   217639   222487   211533   210352   235042   272485   273939   253601   234989   192164

 26    185872   201025   217815   225366   212794   210770   237099   272425   273256   252618   233555   190949
 27    185648   200954   219229   226090   212348   210696   239061   272100   273345   251554   232787   189875
 28    184976   199508   219153   226271   212027   210893   241007   272070   272722  e250688   231205   188579
 29    183615   199248   220320   226400      ---   210352   242801   272989   272722   249463   230233   186478
 30    183016   197812   224103   225883      ---   210401   244030   273434   272100   248269   229211   184350
 31    182683      ---   230311   225391      ---   209444      ---   274534      ---   248353   228037      ---
 
MAX    204998   202049   232127   260016   225624   212076   244030   274534   276925   271508   247274   227517
MIN    182683   184061   197413   219280   208808   208101   207419   244605   272100   248269   228037   184350
 a    4833.52  4840.15  4853.23  4851.34  4846.05  4845.00  4858.35  4869.03  4868.21  4859.92  4852.36  4834.27
 b     -23208   +15129   +32499    -4920   -13364    -2583   +34586   +30504    -2434   -23747   -20316   -43687
 c      33990    18120    58730    93960    81130    78240    14360    12970    36030    37610    42390    60330

CAL YR 1996   MAX 274892  MIN 158481  b +72308  c 524800
WTR YR 1997   MAX 276925  MIN 182683  b -21541  c 567900
 
  	e  Estimated.