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, 1,123,508 acre-ft, July 11, gage height, 4,493.28 ft; minimum, 624,226 acre-ft, Dec. 31, gage height, 4,472.79 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 1997 TO SEPTEMBER 1998 DAILY OBSERVATION AT 2400 HOURS DAY OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP 1 811990 748722 698211 625736 711570 784001 852663 920939 1066588 1116243 1095864 1019266 2 810797 746177 695730 628761 717258 784944 855578 927202 1068179 1118124 1093460 1016660 3 809844 743405 693478 630493 723191 784237 858496 932224 1070036 1119738 1091324 1013537 4 808652 742712 690329 633963 726622 782351 861175 937508 1072691 1120814 1088924 1010937 5 806985 742712 688308 635048 730518 784237 863856 942803 1077209 1121353 1086526 1008080 6 805557 742712 685616 635266 735571 786124 866053 948362 1080136 1122700 1083596 1006005 7 802941 735111 686288 638311 739945 787304 868741 953679 1083596 1122700 1081733 1002894 8 801277 732124 685616 648361 741097 787068 868985 959006 1087592 1122700 1079604 1000046 9 800802 730747 684271 641581 745484 786124 871432 970212 1089724 1123238 1077209 997201 10 799615 728455 682928 643328 746640 785652 872411 975839 1095062 1122969 1075348 994101 11 797006 725936 679350 646171 746640 784237 874371 980711 1099074 1123508 1073222 991262 12 795109 722963 676225 649677 752662 782822 877069 986109 1101217 1122969 1071628 988684 13 792505 720907 673551 652093 754519 782587 876578 990746 1104165 1121084 1069240 986109 14 790376 718170 671993 656053 758703 783058 876578 994617 1106847 1120545 1066853 982766 15 788249 715892 669103 658699 760100 783765 878788 998753 1109262 1119200 1063675 980197 16 786360 713844 666662 662012 762430 786360 879771 1003153 1110335 1118124 1059442 977888 17 784472 712252 664668 667106 764063 788721 881491 1006783 1111677 1116780 1058914 973791 18 781880 711116 662233 673551 765931 791085 882721 1010677 1111141 1115974 1056536 971489 19 779762 711343 659140 678680 768970 792505 884198 1013537 1112751 1113825 1053368 968170 20 777646 709526 656714 681585 770374 794399 885922 1016921 1114094 1113825 1049940 965111 21 775297 707485 654292 684495 774828 797006 886169 1021874 1115168 1114631 1047042 962310 22 772952 705898 650555 686737 776471 803416 888634 1025791 1115974 1112751 1044410 960022 23 770843 707258 647704 689206 778351 811274 890856 1029453 1115437 1111677 1041781 959768 24 768035 708165 645077 690554 780938 818920 895058 1033381 1115437 1111141 1039416 957483 25 765698 709073 641363 693478 782351 825150 897782 1039416 1114094 1108725 1036791 958752 26 763363 710435 638747 696181 783765 829713 901501 1044937 1113825 1107384 1034168 957483 27 760799 706578 635918 698211 784944 836213 905226 1049676 1114631 1106579 1034430 957737 28 758936 704992 633311 700469 784708 840073 908709 1053104 1114900 1103897 1028144 956214 29 756842 702503 630060 703860 --- 843940 912197 1057064 1115974 1102288 1026314 954693 30 754286 700469 626815 706125 --- 847086 916439 1060764 1115974 1099877 1022918 953172 31 751270 --- 624226 707938 --- 850721 --- 1064204 --- 1098271 1021874 --- MAX 811990 748722 698211 707938 784944 850721 916439 1064204 1115974 1123508 1095864 1019266 MIN 751270 700469 624226 625736 711570 782351 852663 920939 1066588 1098271 1021874 953172 a 4478.46 4476.24 4472.79 4476.57 4479.89 4482.65 4485.32 4491.06 4493.00 4492.34 4489.45 4486.78 b -62391 -50801 -76243 +83712 +76770 +66013 +65718 +147765 +51770 -17703 -76397 -68702 CAL YR 1997 MAX 968680 MIN 624226 b -249165 WTR YR 1998 MAX 1123508 MIN 624226 b +139511 a Gage height, in feet, at end of month. b Change in contents, in acre-feet.
USGS Water Resources of California