1997 California Hydrologic Data Report 


                                    11399000 LAKE ALMANOR AT PRATTVILLE, CA
LOCATION.--Lat 40°12'46", long 121°09'43", in SW 1/4 NE 1/4 sec.11, T.27 N., R.7 E., Plumas County,    Hydrologic Unit 18020121, Lassen National Forest, at intake tower to Butt Valley Tunnel at Prattville, 4.7 mi northwest of Lake Almanor Dam, and 5.6 mi northwest of Canyondam.

DRAINAGE AREA.--491 mi2.

PERIOD OF RECORD.--July 1913 to current year. Monthly contents only for some periods, published in WSP 1315-A. Published as "near Prattville" 1937-60. Prior to October 1964, records published as usable contents.

REVISED RECORDS.--WSP 1931: Drainage area.

GAGE.--Nonrecording gage read once daily. Datum of gage is 10.23 ft below sea level (levels by Pacific Gas & Electric Co.). Prior to June 1, 1965, nonrecording gage at site 4.7 mi southeast at same datum.

REMARKS.--Lake is formed by earthfill dam; storage began in July 1913; dam raised to gage height 4,455 ft in 1917 and 4,515 ft in 1927. Usable capacity, 1,174,887 acre-ft between gage heights 4,422 ft, invert of outlet, and 4,495.5 ft, maximum storage limit. Dead storage, 8,948 acre-ft.  Water is diverted by tunnel and penstock to Butt Valley Powerplant (station 11400600) and then is used for power development in the North Fork Feather River. Figures given, including extremes, represent total contents at 2400 hours. See schematic diagram of North Fork Feather River basin.

COOPERATION.--Records were collected by Pacific Gas & Electric Co., 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, 1,142,960 acre-ft, June 8, 1982, gage height, 4,494.00 ft; minimum, 5,230 acre-ft, Feb. 5, 1918, gage height, 4,416.1 ft.

EXTREMES FOR CURRENT YEAR.--Maximum contents, 968,680 acre-ft, June 12, gage height, 4,487.39 ft; minimum, 793,925 acre-ft, Dec. 3, gage height, 4,480.28 ft.

       Capacity table (gage height, in feet, and contents, in acre-feet)
       (Based on surveys by Pacific Gas & Electric Co. in 1924 and 1926)
       4,422      8,948     4,434     49,510     4,460       376,686
       4,424     10,067     4,437     74,189     4,470       565,519
       4,426     11,260     4,440    101,869     4,480       787,304
       4,428     13,480     4,445    156,414     4,490     1,036,269
       4,430     21,200     4,450    220,848     4,495.5   1,183,835
       4,432     34,173     4,455     94,531 


                   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    896296   836695   795109   914941   915939   841039   881245   934236   967405   952412   921189   855092
  2    894811   834767   794873   943561   915440   841764   883213   935242   967150   951652   920939   854120
  3    892832   831878   793925   959260   912696   840314   883952   936753   966640   951146   920688   853148
  4    891350   830194   796531   965875   910951   838625   884937   938264   966385   949880   917688   853634
  5    889868   828511   798429   965875   908211   837901   886662   939776   966130   949121   916689   852177

  6    888141   826350   799140   965365   906221   836454   887155   941290   965620   948615   914192   850721
  7    886662   823471   799615   962819   903984   836213   889128   941542   965875   947856   911449   849024
  8    884690   821553   800565   960276   901005   837418   890362   943308   965620   946845   908958   847813
  9    883213   819159   804843   957737   898773   838142   891844   944823   966640   946087   906469   845875
 10    880754   818202   812229   955453   896048   838625   892338   946592   967660   945329   904232   843456

 11    879034   816289   816289   952665   893574   839590   893080   948615   968170   943813   902990   841281
 12    876824   814138   818441   950133   891844   840314   894069   950386   968680   943056   901253   839107
 13    874616   811990   821074   945076   887648   841522   895553   952159   968170   942046   899269   837177
 14    872166   809605   822272   940533   885183   842489   896296   953425   967150   941037   897286   836454
 15    870208   807223   822752   937257   882475   843456   897286   954946   967150   940029   895306   834767

 16    868496   805557   822752   934236   880508   847570   898525   955961   966895   939020   892585   832359
 17    866053   805557   822752   932727   877315   849509   899764   957229   965875   937508   890362   831396
 18    865320   805319   822752   928708   874371   851207   902245   958245   965365   937005   888634   829953
 19    863125   806985   822752   925697   870942   852905   905723   959260   964601   935746   887401   828031
 20    859957   806985   822991   923442   867274   854606   908709   960022   963583   934991   884690   827791

 21    857280   806509   823711   922190   864344   856793   912945   960531   962565   933733   883213   826590
 22    854849   807461   825870   924194   860931   859226   916189   960531   961802   932476   880754   825390
 23    852905   806985   824670   921940   858739   861418   918438   963074   960531   931470   877806   823711
 24    852177   806033   823950   920188   854363   863368   921189   964346   959768   930465   875107   822752
 25    851207   804843   823471   923192   851207   865809   922941   965111   959006   928959   872411   821314

 26    848782   803178   828031   922941   847328   868252   925196   965620   957483   928206   869230   819638
 27    845875   801752   830194   921689   846844   870698   926951   966385   956468   927202   866297   818680
 28    842972   799853   834526   921189   843456   872656   929210   966895   954946   926199   863612   816289
 29    843456   798429   838142   920438      ---   874862   930214   966895   953425   924945   861418   815572
 30    841764   797006   850236   918938      ---   877069   932224   966895   953172   923692   858009   813661
 31    838866      ---   873391   917938      ---   879279      ---   966895      ---   922440   856307      ---

MAX    896296   836695   873391   965875   915939   879279   932224   966895   968680   952412   921189   855092
MIN    838866   797006   793925   914941   843456   836213   881245   934236   953172   922440   856307   813661
 a    4482.16  4480.41  4483.58  4485.38  4482.35  4483.82  4485.95  4487.32  4486.78  4485.56  4482.88  4481.11
 b     -58668   -41860   +76385   +44547   -74482   +35823   +52945   +34671   -13723   -30732   -66133   -42646

CAL YR 1996   MAX 1129715  MIN 793925  b   -735
WTR YR 1997   MAX  968680  MIN 793925  b -83873