USGS 1995 California Hydrologic Data Report
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 (AT 2400) 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 (AT 2400) FOR CURRENT YEAR.--Maximum contents, 1,137,013 acre-ft, July 9, 10, gage height, 4,493.78 ft;
minimum, 695,054 acre-ft, Dec. 31, gage height, 4,476.00 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 4,455 294,531
RESERVOIR STORAGE (ACRE-FEET), WATER YEAR OCTOBER 1994 TO SEPTEMBER 1995
DAILY OBSERVATION AT 2400 HOURS
DAY OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP
1 754983 708165 713844 695730 796768 847086 972000 1014318 1099877 1131606 1103093 1018223
2 752662 708619 713616 696181 801277 850479 971234 1023963 1102557 1132417 1100145 1014578
3 750575 708619 717714 697308 805081 853877 970212 1031285 1105774 1133228 1095597 1011977
4 749648 709299 720907 697534 808414 856793 969191 1036528 1107384 1133498 1093193 1009379
5 748259 711797 719538 699791 811036 858983 969191 1039941 1110067 1134850 1090791 1007042
6 745946 714526 718854 701599 814138 861906 969957 1043621 1111677 1135120 1087592 1003671
7 744328 714754 717714 706805 816767 863612 973023 1045989 1112483 1135931 1085194 1000823
8 741328 714981 715436 713844 819638 867519 976351 1047306 1112751 1136743 1081999 998494
9 739023 719766 713616 722277 821553 883213 978658 1048622 1113825 1137013 1078805 995909
10 737181 718854 712479 728455 824190 902990 980197 1051522 1113825 1137013 1075614 993326
11 735341 719082 713389 732583 826110 913444 980454 1052049 1115168 1136472 1073222 994101
12 733962 719538 712479 735341 827550 920438 980197 1054424 1117318 1135391 1070036 990746
13 732124 719310 711116 741789 831156 926951 982509 1056272 1117318 1134850 1067914 987912
14 730289 718170 708619 748028 833081 933481 982766 1058385 1118931 1134309 1065264 984308
15 727996 717942 707258 752662 835008 938264 983794 1059442 1122969 1133498 1062087 981738
16 726393 717714 706351 755680 836213 942046 984308 1060764 1125395 1135120 1058914 980197
17 724563 716803 704766 757540 836936 945581 984051 1061558 1125126 1134039 1056008 978401
18 723191 714981 705898 760333 836454 950386 983537 1063145 1125935 1133498 1053104 976607
19 721821 713616 704540 762663 835490 953932 983023 1065528 1125395 1132687 1050467 974047
20 719766 714071 703408 764297 834767 961802 981995 1068179 1127824 1130255 1047832 973535
21 717714 713389 702277 766632 834526 966130 980454 1070301 1128094 1127284 1045200 969957
22 716347 712479 701147 769906 836213 974047 981224 1073222 1128094 1125395 1042569 967405
23 715436 711343 698888 772952 836695 980454 980967 1075614 1127824 1123238 1037315 964856
24 714071 712025 699114 775767 838625 981738 979941 1079071 1127554 1121891 1033381 962819
25 713389 714754 699565 777411 840073 981738 979171 1081733 1127824 1119469 1031285 960276
26 711797 714981 698888 779997 841764 979171 978401 1084395 1128364 1117318 1027883 957991
27 708846 715436 697985 781645 843698 977120 979427 1087059 1128904 1114900 1025007 955707
28 707938 715209 697985 783529 844665 976607 980454 1089724 1129715 1112483 1022135 953425
29 707712 713844 697083 785180 --- 974814 989973 1092659 1130255 1110335 1020309 952919
30 708619 715664 696181 787304 --- 974047 998235 1095330 1130796 1107384 1019787 953932
31 707485 --- 695054 791558 --- 972767 --- 1097736 --- 1104970 1019266 ---
MAX 754983 719766 720907 791558 844665 981738 998235 1097736 1130796 1137013 1103093 1018223
MIN 707485 708165 695054 695730 796768 847086 969191 1014318 1099877 1104970 1019266 952919
a 4476.55 4476.91 4476.00 4480.18 4482.40 4487.55 4488.54 4492.32 4493.55 4492.59 4489.35 4486.81
b -49125 +8179 -20610 +96504 +53107 +128102 +25468 +99501 +33060 -25826 -85704 -65334
CAL YR 1994 MAX 887894 MIN 695054 b +1351
WTR YR 1995 MAX 1137013 MIN 695054 b +197322
a Gage height, in feet, at end of month.
b Change in contents, in acre-feet.
U.S. Geological Survey