USGS
1995 California Hydrologic Data Report
11446200 FOLSOM LAKE NEAR FOLSOM, CA
LOCATION.--Lat 38`42'29", long 121`09'22", in NW 1/4 NE 1/4 sec.24, T.10 N., R.7 E., Sacramento County,
Hydrologic Unit 18020128, near center of dam on American River, 0.7 mi downstream from South Fork American
River, and 2.3 mi northeast of Folsom.
DRAINAGE AREA.--1,861 mi2.
PERIOD OF RECORD.--February 1955 to current year. Prior to October 1959, published as Folsom Reservoir near
Folsom.
REVISED RECORDS.--WSP 1931: Drainage area.
GAGE.--Water-stage recorder. Datum of gage is sea level (levels by U.S. Bureau of Reclamation).
REMARKS.--Reservoir is formed by concrete gravity-type dam with rolled-earth-wing dams, auxiliary dams, and
dikes, completed May 14, 1956; storage began Feb. 25, 1955. Total capacity, 1,010,300 acre-ft between
elevations 205.5 ft, invert of lower tier of river outlets, and 466.0 ft gross pool elevation, all of which
are available for release. Spillway design flood pool elevation, 475.4 ft, capacity, 1,120,200 acre-ft.
Records, including extremes, represent usable contents at 2400 hours. See schematic diagram of lower
Sacramento River basin.
COOPERATION.--Records provided by U.S. Bureau of Reclamation.
EXTREMES FOR PERIOD OF RECORD.--Maximum contents, 1,024,400 acre-ft, June 15, 1963, elevation, 467.23 ft; minimum
since storage pool first filled, 140,600 acre-ft, Nov. 20, 21, 1977, elevation, 347.57 ft.
EXTREMES FOR CURRENT YEAR.--Maximum contents, 970,500 acre-ft, July 9, elevation, 465.42 ft; minimum,
189,200 acre-ft, Dec. 2, elevation, 364.30 ft.
Capacity table (elevation, in feet, and contents, in acre-feet)
(Based on survey by U.S. Bureau of Reclamation in 1992)
345 123,600 380 258,600 440 703,800
350 137,900 390 314,100 460 908,400
360 170,600 400 376,900 479 1,125,000
370 210,500 420 525,500
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 216500 205100 189600 252700 562300 572500 590200 790000 758700 952500 601000 573000
2 215700 205100 189200 252800 562600 572700 597700 824600 769900 954500 598000 569900
3 215300 203300 192700 252900 560100 590900 605600 832300 783300 956900 595600 566400
4 215400 200600 217600 255100 559400 584000 614900 826900 796600 960800 592800 563800
5 215300 198800 230300 265000 557600 572400 624700 814700 811300 964100 589400 560900
6 215500 201300 236000 273200 555000 565600 634400 799700 821200 965800 587100 558000
7 215600 203500 239200 286400 551600 559600 649300 781300 828700 966800 585400 555200
8 215600 202700 240800 306600 549000 553100 672000 762700 833800 968500 584600 552700
9 215200 203300 241300 343500 544600 565400 688400 745200 838400 970500 585000 550600
10 215300 203600 241400 432900 541400 586700 702100 727400 843900 969400 583800 548000
11 215100 203500 241100 461900 541900 625100 709100 711900 852200 965700 582900 544500
12 215000 203300 241300 441900 543200 605100 712400 697600 862500 962000 581200 540600
13 214700 202000 242700 454800 546800 572900 720100 687000 872700 958400 580200 536400
14 214500 200300 246600 518700 550400 571000 727800 675200 882400 955200 580400 531800
15 214000 199800 248000 563600 552700 567900 733900 664000 896000 950700 581200 528100
16 212900 198300 248700 582000 555200 560700 738100 654000 909300 946400 579300 524200
17 211100 196700 248600 588100 557100 548700 741200 645700 909400 898100 579200 518600
18 211400 196700 248200 585800 558900 548000 743500 639900 907700 839200 579600 514400
19 210900 196000 247800 581200 560300 547800 745400 636100 907700 791900 579200 511600
20 210300 194300 246500 577700 561900 556300 747500 634900 908200 755900 578800 507500
21 209300 192700 245800 574900 563700 561000 748800 638300 908900 727600 577600 503900
22 208800 192000 245700 572200 565200 569000 748900 643900 910400 704700 577300 499400
23 208200 191700 245400 574500 568300 584700 748800 650600 913600 685000 577500 495200
24 207100 191100 246100 577600 570900 580200 748600 660000 919700 667700 576600 491100
25 207000 190200 247900 585500 573100 571800 748800 668800 931000 654000 575500 488000
26 206700 190300 248300 590900 573700 563400 750900 679000 940100 643500 575500 483800
27 206900 190300 249200 586700 574100 561800 753200 691100 945800 633500 575900 480200
28 206800 189800 249800 557500 574200 567200 753000 703700 949900 624200 575500 476400
29 206500 190200 250700 554700 --- 573300 752600 716800 952500 617100 575500 472500
30 205600 189500 251500 557000 --- 579400 756700 730100 953100 609700 575500 466100
31 204800 --- 252300 559100 --- 584700 --- 743900 --- 604600 574500 ---
MAX 216500 205100 252300 590900 574200 625100 756700 832300 953100 970500 601000 573000
MIN 204800 189500 189200 252700 541400 547800 590200 634900 758700 604600 574500 466100
a 368.11 364.37 378.28 423.73 425.50 426.71 445.16 443.86 463.85 428.98 425.53 412.17
b -12100 -15300 +62800 +306800 +15100 +10500 +172000 -12800 +209200 -348500 -30100 -108400
c 1580 580 290 780 1590 2360 2740 3130 5600 6510 5500 3370
CAL YR 1994 b -140800
WTR YR 1995 b +249200
a Elevation, in feet, at end of month.
b Change in contents, in acre-feet.
c Evaporation, in acre-feet, provided by U.S. Bureau of Reclamation; not reviewed by U.S. Geological Survey.
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