10290300  UPPER TWIN LAKE NEAR BRIDGEPORT, CA

LOCATION.--Lat 38°09'15", long 119°20'58", in NW 1/4 NE 1/4 sec.5, T.3 N., R24 E., Mono County, Hydrologic Unit
   16050301, in Toiyabe National Forest, at outlet of upper lake dam on Robinson Creek, and 10 mi southwest of
   Bridgeport.

DRAINAGE AREA.--29.5 mi2.

PERIOD OF RECORD.--December 1961 to February 1964, September 1964 to current year.

GAGE.--Non-recording gage.  Datum of gage is 7,212.86 ft above sea level (project datum of U.S. Indian Irrigation
   Service).

REMARKS.--Contents regulated by dam at outlet.  Figures given herein represent usable contents.  Usable contents,
   2,070 acre-ft between elevations 7,200 ft, natural rim, and 7,207 ft, spillway crest.  These data are reviewed
   and provided by the Nevada District Office, U.S. Geological Survey.

EXTREMES FOR PERIOD OF RECORD.--Maximum contents observed, 2,990 acre-ft, July 7, 1983, elevation, 7,209.85 ft;
   minimum observed, 30 acre-ft, November 1, 1990, elevation, 7,200.11 ft.

EXTREMES OUTSIDE PERIOD OF RECORD.--No contents observed October 17, 1961.

EXTREMES FOR CURRENT YEAR.--Maximum contents observed, 2,690 acre-ft, July 3, elevation, 7,208.95 ft; minimum
   observed, 1,930 acre-ft, March 28, elevation, 7,206.55 ft, (affected by high winds).


   MONTHEND ELEVATION, IN FEET ABOVE SEA LEVEL, AND TOTAL CONTENTS, WATER YEAR OCTOBER 1995 TO SEPTEMBER 1996
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    Date                                                     Elevation           Contents      Change in contents
                                                                (ft)             (acre-ft)          (acre-ft)
_________________________________________________________________________________________________________________

   September 30. . . . . . . . . . . . . . . . . . . . . . . 7,207.79               2,320                 --
   October   31. . . . . . . . . . . . . . . . . . . . . . . 7,207.40               2,700               -120
   November  30. . . . . . . . . . . . . . . . . . . . . . . 7,207.28               2,160                -40
   December  31. . . . . . . . . . . . . . . . . . . . . . . 7,207.44               2,210                +50

      CALENDAR YEAR 1996 . . . . . . . . . . . . . . . . . .    --                     --               -110

   January   31. . . . . . . . . . . . . . . . . . . . . . . 7,207.30               2,170                -40
   February  29. . . . . . . . . . . . . . . . . . . . . . . 7,207.37               2,190                +20
   March     31. . . . . . . . . . . . . . . . . . . . . . . 7,206.68               1,970               -220
   April     30. . . . . . . . . . . . . . . . . . . . . . . 7,208.02               2,400               +430
   May       31. . . . . . . . . . . . . . . . . . . . . . . 7,208.23               2,460                +60
   June      30. . . . . . . . . . . . . . . . . . . . . . . 7,208.89               2,670               +210
   July      31. . . . . . . . . . . . . . . . . . . . . . . 7,208.35               2,500               -170
   August    31. . . . . . . . . . . . . . . . . . . . . . . 7,207.75               2,310               -190
   September 30. . . . . . . . . . . . . . . . . . . . . . . 7,207.50               2,230                -80
                                                             ____________________________________________________

      WATER YEAR 1996. . . . . . . . . . . . . . . . . . . .    --                     --                -90
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    NOTE.--Monthend elevations are interpolated from readings made during the year.