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., R.24 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, Nov. 1, 1990, elevation, 7,200.11 ft.
EXTREMES OUTSIDE PERIOD OF RECORD.-No usable contents observed Oct. 17, 1961.
EXTREMES FOR CURRENT YEAR.-Maximum contents observed, 2,800 acre-ft, July 1, elevation, 7,209.28 ft; minimum observed, 1,750 acre-ft, Nov. 5, elevation, 7,206.00 ft.

  MONTHEND ELEVATION, IN FEET ABOVE SEA LEVEL, AND TOTAL CONTENTS, WATER YEAR OCTOBER 1997 TO SEPTEMBER 1998
  Date	Elevation
  (ft)	Contents
  (acre-ft)	Change in contents
  (acre-ft)
  September 30		7206.92	2,040	   -
  October 31		7206.12	1,790	-250
  November 30		7206.63	1,950	+160
  December 31		7207.10	2,100	+150
CALENDAR YEAR 1997		-	-	-120
  January 31		7207.00	2,070	-30
  February 28		7206.19	1,810	-260
  March 31		7207.04	2,080	+270
  April 30		7207.90	2,360	+280
  May 31		7207.09	2,100	-260
  June 30		7209.20	2,780	+680
  July 31		7208.62	2,590	-190
  August 31		7207.89	2,360	-230
  September 30		7207.70	2,290	-70
WATER YEAR 1998		-	-	+250
NOTE.-Monthend elevations are interpolated from readings made during the year.