Water-Data Report 2008 11276500 near , CA Basin

LOCATION.--Lat 37°5615, long 119°4750 referenced to North American Datum of 1927, in SW ¼ SE ¼ sec.17, T.1 N., R.20 E., Tuolumne County, CA, Hydrologic Unit 18040009, in , on left bank 0.9 mi downstream from OShaughnessy Dam at Hetch Hetchy, 2.5 mi downstream from Falls Creek, and 5.0 mi northeast of Mather. DRAINAGE AREA.--457 mi². SURFACE-WATER RECORDS PERIOD OF RECORD.--October 1910 to current year. Monthly discharge only for some periods, published in WSP 1315-A. Published as "at Hetch Hetchy damsite, near Sequoia" 1910-14 and as "below Hetch Hetchy damsite, near Sequoia" 1915-18. REVISED RECORDS.--WSP 1930: Drainage area. GAGE.--Water-stage recorder, crest-stage gage with concrete control since May 5, 1970. Elevation of gage is 3,480 ft above NGVD of 1929, from topographic map. Prior to Jan. 1, 1915, water-stage recorder at site 1 mi upstream, at damsite, at different datum. Jan. 1, 1915, to Sept. 3, 1968, water-stage recorder, at same site and datum. Oct. 1, 1968, to May 4, 1970, nonrecording gage at site 0.5 mi upstream at different datum. REMARKS.--Records good. Flow regulated by Hetch Hetchy Reservoir (station 11275500) 0.9 mi upstream beginning in April 1923. Flow diverted upstream from station through tunnel to Robert C. Kirkwood Powerplant and Hetch Hetchy Aqueduct beginning Apr. 26, 1967. See schematic diagram of Tuolumne River Basin available from the Water Science Center. EXTREMES FOR PERIOD OF RECORD.--Maximum discharge, 16,400 ft³/s, Jan. 3, 1997, gage height, 15.08 ft; no flow at times in 1968-70.

U.S. Department of the Interior U.S. Geological Survey Water-Data Report 2008 11276500 Tuolumne River near Hetch Hetchy, CA—Continued

DISCHARGE, CUBIC FEET PER SECOND WATER YEAR OCTOBER 2007 TO SEPTEMBER 2008 DAILY MEAN VALUES Day Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

1 47 37 33 38 60 69 68 160 107 123 117 112 2 40 37 33 38 69 68 79 155 119 122 119 112 3 39 37 32 38 71 69 82 154 121 122 118 112 4 39 37 32 47 69 70 82 156 122 122 119 112 5 39 37 32 41 69 69 83 157 120 122 119 112 6 39 37 33 40 69 69 83 153 120 121 119 112 7 39 37 33 40 68 69 127 104 119 120 119 112 8 38 37 31 41 68 68 151 88 165 120 119 114 9 38 37 31 41 68 68 150 88 190 119 119 114 10 38 37 31 42 68 68 149 88 746 119 118 114 11 39 37 32 41 68 68 148 89 1,710 118 118 114 12 41 37 32 41 68 69 148 89 1,710 119 119 114 13 40 37 32 41 68 69 149 89 1,450 122 118 113 14 40 36 32 41 68 69 149 88 1,060 120 119 113 15 39 36 32 41 68 69 150 88 908 118 120 113 16 37 36 32 41 68 69 150 88 1,110 118 120 112 17 37 36 33 41 68 69 150 89 1,190 118 120 95 18 37 36 34 40 67 69 150 87 736 119 120 69 19 37 35 32 40 67 67 151 87 233 118 120 68 20 37 35 34 40 68 65 151 88 188 117 120 67 21 37 35 36 40 68 64 151 88 242 118 120 68 22 37 35 37 40 73 64 150 88 448 119 120 67 23 37 34 37 41 70 64 150 87 572 118 120 67 24 37 34 37 41 86 64 149 86 441 117 119 67 25 37 34 37 40 74 64 148 86 267 118 120 67 26 37 34 37 40 71 62 148 86 194 118 115 67 27 37 34 38 46 70 63 149 240 193 119 112 67 28 37 34 38 46 69 64 150 3,060 192 119 112 67 29 37 33 37 42 69 63 153 306 154 119 112 67 30 37 33 37 42 --- 64 147 90 123 119 112 67 31 37 --- 37 42 --- 64 --- 88 --- 118 112 --- Total 1,187 1,071 1,054 1,273 2,007 2,070 4,045 6,490 15,050 3,699 3,654 2,775 Mean 38.3 35.7 34.0 41.1 69.2 66.8 135 209 502 119 118 92.5 Max 47 37 38 47 86 70 153 3,060 1,710 123 120 114 Min 37 33 31 38 60 62 68 86 107 117 112 67 Ac-ft 2,350 2,120 2,090 2,520 3,980 4,110 8,020 12,870 29,850 7,340 7,250 5,500

STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1911 - 1966, BY WATER YEAR (WY) Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Mean 534 516 544 528 519 620 971 2,005 3,149 1,396 636 548 Max 813 780 2,281 1,221 1,556 1,078 2,803 5,336 7,859 4,624 1,320 1,143 (WY) (1949) (1939) (1951) (1965) (1965) (1916) (1952) (1919) (1911) (1911) (1939) (1939) Min 13.8 1.52 1.83 2.51 34.2 11.2 507 493 480 279 27.1 5.83 (WY) (1925) (1924) (1924) (1924) (1924) (1925) (1937) (1961) (1924) (1919) (1924) (1923)

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SUMMARY STATISTICS Water Years 1911 - 1966 Annual mean 997 Highest annual mean 1,724 1911 Lowest annual mean 516 1924 Highest daily mean 11,400 Jun 18, 1911 Lowest daily mean 1.3 Nov 2, 1923 Annual seven-day minimum 1.4 Nov 1, 1923 Maximum peak flow 12,900 Jun 1, 1943 Maximum peak stage 13.90 Jun 1, 1943 Annual runoff (ac-ft) 722,600 10 percent exceeds 2,230 50 percent exceeds 721 90 percent exceeds 115

STATISTICS OF MONTHLY MEAN DATA FOR WATER YEARS 1968 - 2008, BY WATER YEAR (WY) Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Mean 52.3 61.8 73.2 111 72.6 82.0 218 1,092 1,731 782 155 78.1 Max 164 561 618 2,105 305 489 1,371 3,327 5,885 5,149 1,263 125 (WY) (1987) (1987) (1997) (1997) (1974) (1983) (1986) (1969) (1983) (1983) (1983) (1989) Min 31.1 33.6 34.0 33.5 31.7 29.9 33.6 49.0 71.2 68.2 66.7 31.6 (WY) (1969) (1991) (2008) (1977) (1971) (1974) (1981) (1990) (1977) (1968) (1974) (1970)

SUMMARY STATISTICS Calendar Year 2007 Water Year 2008 Water Years 1968 - 2008 Annual total 32,150 44,375 Annual mean 88.1 121 376 Highest annual mean 1,433 1983 Lowest annual mean 49.5 1977 Highest daily mean 2,500 May 21 3,060 May 28 13,800 Jan 3, 1997 Lowest daily mean 31 Dec 8 31 Dec 8 0.00 Oct 3, 1968 Annual seven-day minimum 32 Dec 8 32 Dec 8 0.00 Feb 20, 1970 Maximum peak flow 6,720 May 28 16,400 Jan 3, 1997 Maximum peak stage 11.48 May 28 15.08 Jan 3, 1997 Annual runoff (ac-ft) 63,770 88,020 272,800 10 percent exceeds 108 150 869 50 percent exceeds 53 69 68 90 percent exceeds 36 36 36

— 3 — Water-Data Report 2008 11276500 Tuolumne River near Hetch Hetchy, CA—Continued

10,000

5,000

2,000

1,000

500

200

100

50 MEAN DISCHARGE, CUBIC FEET PER SECOND MEAN DISCHARGE, CUBIC FEET PER SECOND 20

10 O N D J F M A M J J A S 2007 2008

— 4 — Water-Data Report 2008 11276500 Tuolumne River near Hetch Hetchy, CA—Continued

WATER-QUALITY RECORDS PERIOD OF DAILY RECORD.--October 1971 to September 1972, August 1987 to current year. WATER TEMPERATURE: October 1971 to September 1972, August 1987 to current year. INSTRUMENTATION.--Water-temperature recorder October 1971 to September 1972, and since August 1987. REMARKS.--Water-temperature records rated excellent except for June 25 to Aug. 29, which are rated good. Water-temperature recorder installed Aug. 13, 1987, located 0.6 mi upstream from gaging station on left bank at road bridge. Water temperature can be affected by releases from O'Shaughnessy Dam. EXTREMES FOR PERIOD OF DAILY RECORD.-- WATER TEMPERATURE: Maximum recorded, 19.5°C, July 12, 1996, June 30, 2000; minimum recorded, 4.0°C, Mar. 25, 1991. EXTREMES FOR CURRENT YEAR.-- WATER TEMPERATURE: Maximum recorded, 15.2°C, June 22; minimum recorded, 5.6°C, Feb. 23.

TEMPERATURE, WATER, DEGREES CELSIUS WATER YEAR OCTOBER 2007 TO SEPTEMBER 2008 Day Max Min Max Min Max Min Max Min Max Min Max Min

October November December January February March 1 11.2 9.5 11.3 10.2 9.9 9.3 9.2 8.5 7.0 6.5 7.1 6.0 2 11.4 9.6 11.2 10.2 10.0 9.1 9.1 8.4 6.8 6.0 6.9 6.0 3 11.4 9.7 11.1 9.9 10.2 9.2 9.1 8.4 6.8 6.0 7.0 5.8 4 11.1 9.6 11.1 10.0 11.0 9.7 8.9 7.8 6.8 6.0 7.0 5.8 5 9.9 9.4 11.3 10.2 11.1 10.2 8.6 7.2 6.8 5.9 7.2 5.7 6 10.7 9.1 11.4 10.4 10.5 10.0 8.5 7.6 7.1 6.3 6.9 5.8 7 10.9 9.3 11.4 10.3 10.2 10.0 8.3 7.8 7.0 6.1 7.2 5.9 8 11.1 9.6 11.2 10.4 10.3 9.5 8.2 7.9 7.0 6.0 7.2 6.0 9 11.1 9.6 11.2 10.6 10.3 9.4 8.5 7.8 7.1 6.2 7.1 5.8 10 11.0 9.8 11.1 10.3 10.2 9.4 8.4 7.8 7.3 6.3 7.3 6.2 11 11.2 9.8 11.3 10.3 10.3 9.3 8.4 7.6 7.3 6.3 7.2 6.2 12 10.6 10.0 10.9 10.2 10.3 9.5 8.5 7.7 7.3 6.3 7.2 6.1 13 11.2 9.9 11.5 10.4 10.3 9.6 8.5 7.5 7.0 5.9 7.4 6.4 14 11.2 9.8 11.4 10.4 10.3 9.5 8.5 7.7 6.4 5.7 6.7 6.1 15 10.9 9.9 11.5 10.5 10.4 9.7 8.4 7.7 6.9 5.8 6.6 5.7 16 10.6 10.1 11.4 10.6 10.2 9.6 8.0 7.3 7.0 5.9 7.1 5.7 17 10.7 9.9 11.2 10.3 10.1 9.6 8.1 7.3 7.0 6.0 7.2 5.8 18 10.8 9.9 11.2 10.3 9.9 9.6 8.1 7.3 7.0 6.1 7.5 6.1 19 11.5 9.9 11.1 10.2 10.2 9.6 8.0 7.2 6.7 6.0 7.4 6.1 20 10.9 9.9 11.0 10.0 10.0 9.2 8.0 7.1 6.7 6.0 7.5 6.2 21 10.8 9.5 10.9 9.8 9.5 8.9 7.5 7.0 6.2 5.9 7.5 6.0 22 11.0 9.8 10.7 9.9 9.8 9.0 7.6 6.9 6.2 5.7 7.7 6.2 23 11.4 10.0 10.3 9.6 10.0 9.3 7.4 7.0 6.2 5.6 7.7 6.3 24 11.4 10.2 10.7 9.5 10.1 9.2 7.5 6.9 6.2 5.7 7.8 6.3 25 11.2 10.1 10.6 9.9 9.4 8.9 7.8 7.0 6.8 5.8 7.2 6.4 26 11.3 10.1 10.6 9.6 9.3 8.4 7.9 7.0 6.9 5.8 7.8 6.5 27 11.2 10.2 10.6 9.7 8.8 8.3 7.5 7.1 6.9 6.0 7.6 6.3 28 11.7 10.6 10.6 9.6 9.2 8.6 7.2 6.3 7.3 6.0 7.7 6.6 29 11.1 10.6 10.6 9.7 9.5 9.0 6.8 6.2 7.5 6.1 7.6 6.7 30 11.3 10.3 10.3 9.6 9.4 8.7 7.3 6.6 ------7.3 6.5 31 11.4 10.3 ------9.2 8.4 7.0 6.4 ------7.7 6.1 Month 11.7 9.1 11.5 9.5 11.1 8.3 9.2 6.2 7.5 5.6 7.8 5.7

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TEMPERATURE, WATER, DEGREES CELSIUS WATER YEAR OCTOBER 2007 TO SEPTEMBER 2008 Day Max Min Max Min Max Min Max Min Max Min Max Min

April May June July August September 1 7.5 6.4 9.7 8.5 9.9 8.8 12.7 11.4 11.6 10.4 10.7 9.6 2 7.5 6.5 9.8 8.6 9.9 8.7 13.0 11.6 11.3 10.2 10.9 9.8 3 7.8 6.5 9.8 8.7 9.7 8.8 13.0 11.7 11.2 10.1 11.0 9.9 4 7.8 6.6 9.6 8.8 9.7 8.8 13.0 11.8 11.0 9.9 11.1 10.0 5 7.8 6.5 9.8 9.0 9.8 8.4 13.2 11.7 10.9 9.9 11.1 10.0 6 7.9 6.6 10.1 8.9 10.3 8.9 13.3 11.9 11.2 10.0 11.3 10.1 7 8.4 6.4 9.6 8.2 10.4 9.0 13.6 12.1 11.1 9.9 11.2 10.2 8 7.8 7.2 9.5 8.0 10.7 9.4 13.7 12.2 11.1 10.0 11.1 10.2 9 8.3 7.2 9.6 8.0 11.1 9.8 13.7 12.6 11.1 9.9 10.9 10.1 10 8.5 7.3 9.7 8.0 10.4 9.3 13.4 12.3 10.9 9.9 10.9 10.0 11 9.0 7.8 9.6 8.1 9.7 9.2 13.2 12.1 11.1 9.9 11.0 10.1 12 8.9 7.8 9.6 8.0 9.9 9.3 13.3 12.3 11.0 9.9 11.0 10.1 13 9.0 7.9 9.6 7.8 10.0 9.5 13.4 12.3 11.1 10.0 11.1 10.1 14 9.0 7.8 10.2 8.2 10.2 9.6 13.6 12.4 11.2 10.1 11.2 10.1 15 8.5 7.5 10.2 8.6 10.2 9.7 13.7 12.5 11.1 10.1 11.1 10.2 16 8.9 7.8 10.4 8.8 10.2 9.6 13.5 12.2 11.2 10.0 11.0 10.2 17 9.2 7.8 10.4 8.7 10.2 9.5 13.3 12.1 11.2 10.2 11.3 10.2 18 9.1 8.0 10.7 8.8 10.7 9.6 13.2 12.0 11.1 10.0 11.4 10.2 19 9.0 7.9 10.5 8.9 11.8 9.8 13.2 12.0 10.9 10.0 11.4 10.2 20 8.7 7.7 10.4 8.6 12.2 10.4 13.0 11.9 11.0 10.0 11.4 10.2 21 8.9 7.8 9.8 8.5 13.6 10.9 13.0 11.8 11.3 10.1 11.5 10.1 22 8.7 8.0 9.2 8.1 15.2 12.3 12.7 11.6 11.3 10.2 11.2 9.9 23 8.9 8.3 9.3 8.2 13.2 11.7 12.7 11.6 11.2 10.2 11.4 10.1 24 9.2 8.1 8.9 8.5 11.7 10.4 12.7 11.5 11.2 10.2 11.6 10.1 25 9.3 8.3 9.0 8.5 12.1 10.3 12.4 11.4 11.2 10.1 11.6 10.2 26 9.7 8.4 9.2 8.4 12.3 11.1 12.3 11.2 11.2 9.9 11.6 10.3 27 10.0 8.7 9.1 8.6 12.6 11.3 12.0 11.0 11.2 10.1 11.6 10.3 28 10.0 9.0 9.2 8.7 12.5 11.2 12.0 10.9 11.2 10.2 11.6 10.3 29 9.8 8.7 9.7 8.7 12.5 11.1 11.9 10.8 11.2 10.2 11.5 10.6 30 9.6 8.5 10.1 8.5 12.8 11.4 11.6 10.5 11.2 10.1 11.7 10.5 31 ------10.1 8.7 ------11.6 10.4 10.8 9.9 ------Month 10.0 6.4 10.7 7.8 15.2 8.4 13.7 10.4 11.6 9.9 11.7 9.6

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16

14

12

10 DEGREES CELSIUS ,

8 WATER

MAXIMUM AND MINIMUM TEMPERATURE, 6

4 O N D J F M A M J J A S 2007 2008

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CROSS SECTION ANALYSES WATER YEAR OCTOBER 2007 TO SEPTEMBER 2008 DepthTo Loca- bottom tion in at X-sect. sample Sam- Temper- looking loca- pling Stream ature, dwnstrm tion, depth, width, water, ft from Date Time feet feet feet deg C l bank (81903) (00003) (00004) (00010) (00009) Nov 29... 0950 .30 .18 30.0 10.1 1.50 29... 0951 .67 .40 30.0 10.1 4.50 29... 0952 .60 .36 30.0 10.0 7.50 29... 0953 1.11 .67 30.0 10.1 10.5 29... 0954 1.27 1.27 30.0 10.1 13.5 29... 0955 1.10 .66 30.0 10.1 16.5 29... 0956 .81 .49 30.0 10.1 19.5 29... 0957 .77 .46 30.0 10.1 22.5 29... 0958 .47 .28 30.0 10.1 25.5 29... 0959 .90 .54 30.0 10.0 28.5 Aug 29... 0946 .50 .30 40.0 10.5 2.00 29... 0947 .81 .49 40.0 10.5 6.00 29... 0948 1.21 .73 40.0 10.4 10.0 29... 0949 1.57 .94 40.0 10.4 14.0 29... 0950 .93 .56 40.0 10.4 18.0 29... 0951 .80 .48 40.0 10.3 22.0 29... 0952 1.19 .71 40.0 10.4 26.0 29... 0953 .82 .49 40.0 10.4 30.0 29... 0954 .70 .42 40.0 10.4 34.0 29... 0955 .43 .17 40.0 10.5 38.0 Note: Instantaneous discharge at the mean time of cross-sectional measurements: Nov. 29, 33 ft3/s; Aug. 29, 113 ft3/s.

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