b Change in contents, in acre-feet.
                              11234700 MAMMOTH POOL RESERVOIR NEAR BIG CREEK, CA.  


LOCATION - Lat 37°19'40", long 119°19'38", in SE 1/4 SE 1/4 sec.10, T.7 S., R.24 E., Madera County, 
Hydrologic Unit 18040006, Sierra National Forest, in gatehouse of power tunnel intake, 0.7 mi northwest 
of dam on San Joaquin River, and 9.0 mi northwest of town of Big Creek.

DRAINAGE AREA - 995 mi".

PERIOD OF RECORD - October 1959 to current year.

GAGE - Water-stage recorder. Datum of gage is sea level (levels by Southern California Edison Co.).

REMARKS - Reservoir is formed by an earthfill dam; storage began Oct. 8, 1959. Usable capacity, 119,940 
acre-ft, between elevations, 3,100.00 ft, invert of power tunnel, and 3,330.00 ft, crest of spillway. 
Additional storage of 2,780 acre-ft is not available for release. Water is diverted from basin 
through Ward Tunnel (stations 11229500 and 11235500). Water is diverted from Mammoth Pool through tunnel 
for power development and returned to river 8.5 mi downstream from dam. Records, including extremes, 
represent usable contents at 2400 hours. See schematic diagram of lower San Joaquin River Basin.

COOPERATION - Records were collected by Southern California Edison Co., under general supervision of 
the U.S. Geological Survey, in connection with a Federal Energy Regulatory Commission project. Records 
not rounded to U.S. Geological Survey standards.

EXTREMES FOR PERIOD OF RECORD - Maximum contents, 128,944 acre-ft, Jan. 2, 1997, elevation, 3,338.00 
ft; minimum contents since appreciable storage was attained, 1,134 acre-ft, Sept. 25, 1992, elevation, 
3,112.82 ft.

EXTREMES FOR CURRENT YEAR - Maximum contents, 122,764 acre-ft, May 27, elevation, 3,332.54 ft; minimum, 
11,801 acre-ft, Nov. 2, elevation, 3,172.30 ft. Capacity table (elevation, in feet, and contents, 
in acre-feet) (Based on table provided by Southern California Edison Co., dated Nov. 6, 1959) 3,100 
0 3,130 3,114 3,180 14,060 3,260 56,381 3,105 417 3,140 4,605 3,190 17,414 3,280 72,109 3,110 861 3,150 
6,402 3,200 21,400 3,300 89,781 3,115 1,355 3,160 8,618 3,220 31,109 3,320 109,336 3,120 1,900 
3,170 11,165 3,240 42,787 3,340 131,255

RESERVOIR STORAGE (ACRE-FEET), WATER YEAR OCTOBER 1999 TO SEPTEMBER 2000
DAILY OBSERVATION AT 2400 HOURS
DAY      OCT      NOV      DEC      JAN      FEB      MAR      APR      MAY      JUN      JUL      AUG      SEP

1      25917    12086    20477    14088    31744    50086    14029    55798   121425   117307    81107    47393
2      25811    11801    19593    14306    32472    47685    13594    60509   121359   115421    78073    47884
3      25546    11961    19172    14496    32346    47340    14054    66524   121414   113612    75968    48372
4      25869    12189    18598    14717    32214    44370    15419    73035   121648   111385    73897    48809
5      25507    12395    18261    14940    32263    42391    16875    78759   121514   109450    70835    48775

6      25512    12610    17236    15120    33062    40212    17580    83229   121270   107243    69589    48660
7      25570    12835    16691    15346    32858    37808    18455    88292   121214   106338    68025    48399
8      24162    13291    15780    15549    32687    35270    19613    97092   121136   105924    66508    47546
9      23273    13610    15195    15760    33495    32703    20415   103159   120471   105318    65006    47373
10     22514    13891    14557    15971    33868    29873    20963   106318   120051   104674    63804    46299

11     21759    14164    14344    16201    34080    27278    21552   107448   120117   104332    62317    44988
12     21955    14436    13928    16526    35270    24802    22740   107376   120527   104262    60994    43499
13     22178    14704    13309    16779    35859    23482    27945   107468   121414   103771    59979    42234
14     22381    14963    12940    17002    43403    22620    30905   107591   121514   103299    58601    40738
15     22183    15225    12849    17262    46242    22253    31288   106592   121514   103149    56971    39427

16     22104    15532    12659    17993    48600    22095    31082   105833   121759   103059    55211    37867
17     21746    15944    12515    18551    50376    22043    31310   104453   121548   102949    54169    36204
18     21539    16242    12550    23093    51866    21725    31098   103841   121214   102510    54070    34785
19     21277    16578    12579    24583    53055    20922    30329   104895   120870   101623    53828    33395
20     20930    17076    12564    24713    54384    20855    29831   108503   120682   101136    53699    31804

21     20055    17501    12429    23541    56068    19314    29673   113697   120427   100216    53020    30996
22     19295    17837    12046    23758    56780    17425    29657   120914   120383    99339    52350    31212
23     18590    18142    12297    24312    56425    15659    30927   122082   120383    98462    50708    30798
24     17403    18439    12538    27960    55052    14853    31646   122361   120006    96699    49618    29794
25     16052    18735    12774    30648    53232    14882    33450   122238   119820    94641    48439    28526

26     15244    19049    13013    32742    52006    15676    36518   122127   120029    92722    47367    27369
27     14846    19358    13237    33389    51915    16300    41405   122764   120372    90269    47811    26408
28     14879    19656    13464    32775    52801    16279    45767   122562   119907    87886    46915    26115
29     14069    19946    13679    31848    52463    15556    48546   122171   119219    86118    46001    25941
30     13576    20218    13875    31190      ---    15225    51719   121904   118383    85218    46673    25946

31     13175      ---    13995    31093      ---    14765      ---   121526      ---    83779    46934      ---
MAX    25917    20218    20477    33389    56780    50086    51719   122764   121759   117307    81107    48809
MIN    13175    11801    12046    14088    31744    14765    13594    55798   118383    83779    46001    25941
a    3177.08  3197.17  3179.79  3219.97  3254.53  3182.22  3253.47  3331.43  3328.57  3293.44  3246.43  3210.00
b     -13074    +7043    -6223   +17098   +21370   -37698   +36954   +69807    -3143   -34604   -36845   -20988
CAL YR 1999 b -16991
WTR YR 2000 b -303