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Water Year
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COLUMBIA - GRAND COULEE DAM
(
GCDW1
)
Forecasts for Water Year
2026
Official Water Supply
ESP with 10 Days QPF
Ensemble:
2026-07-18
Issued:
2026-07-18
Hide Forecast
Forecast
Period
Forecasts Are in KAF
30 Year
Average
(1991-2020)
90 %
50 %
%
Average
10 %
APR-SEP
55770
56330
92
57548
61483
APR-JUL
48849
48918
93
48968
52774
APR-AUG
53130
53392
92
54003
58186
JAN-SEP
68649
69208
98
70426
70457
JAN-JUL
61728
61797
100
61847
61749
OCT-SEP
79207
79767
101
80985
78842
Experimental Water Supply
HEFS with 15 days EQPF
Ensemble:
2026-07-18
Issued:
2026-07-18
Hide Forecast
APR-SEP
55857
56281
92
57632
61483
APR-JUL
48837
48910
93
49063
52774
APR-AUG
53207
53426
92
53992
58186
JAN-SEP
68736
69159
98
70510
70457
JAN-JUL
61715
61788
100
61941
61749
OCT-SEP
79294
79718
101
81069
78842
Reference
ESP with 0 Days QPF
Ensemble:
2026-07-18
Issued:
2026-07-18
Hide Forecast
APR-SEP
55958
56624
92
57799
61483
APR-JUL
48757
48973
93
49312
52774
APR-AUG
53168
53612
92
54433
58186
JAN-SEP
68836
69502
99
70678
70457
JAN-JUL
61636
61852
100
62191
61749
OCT-SEP
79394
80060
102
81236
78842
Move the mouse over the desired "Forecast Period" to display a graph.
ESP10, 231, 299, 355, 408, 434, 70, , 74
ESP10, 226, 294, 350, 403, 429, 73, , 77
ESP10, 229, 303, 354, 405, 434, 75, , 79
ESP10, 227, 306, 352, 403, 432, 77, , 81
ESP10, 226, 306, 349, 400, 429, 79, , 83
ESP10, 224, 303, 348, 399, 431, 82, , 86
ESP10, 230, 304, 349, 400, 438, 84, , 88
ESP10, 233, 305, 354, 401, 439, 86, , 90
ESP10, 234, 306, 356, 402, 440, 89, , 93
ESP10, 234, 305, 354, 400, 439, 91, , 95
ESP10, 237, 309, 357, 401, 439, 93, , 97
ESP10, 236, 310, 358, 403, 439, 96, , 100
ESP10, 229, 303, 351, 396, 435, 98, , 102
ESP10, 231, 305, 355, 398, 437, 100, , 104
ESP10, 233, 304, 353, 395, 437, 102, , 106
ESP10, 221, 293, 339, 385, 428, 105, , 109
ESP10, 211, 284, 331, 380, 418, 107, , 111
ESP10, 221, 295, 345, 392, 429, 109, , 113
ESP10, 221, 294, 347, 392, 432, 112, , 116
ESP10, 221, 294, 349, 398, 435, 114, , 118
ESP10, 210, 285, 345, 388, 426, 116, , 120
ESP10, 208, 287, 343, 389, 424, 118, , 122
ESP10, 202, 288, 337, 387, 424, 121, , 125
ESP10, 210, 298, 347, 395, 432, 123, , 127
ESP10, 214, 307, 353, 399, 435, 125, , 129
ESP10, 219, 318, 357, 407, 440, 128, , 132
ESP10, 221, 316, 357, 406, 441, 130, , 134
ESP10, 223, 318, 357, 407, 441, 132, , 136
ESP10, 213, 309, 349, 398, 432, 135, , 139
ESP10, 198, 294, 337, 390, 421, 137, , 141
ESP10, 199, 295, 341, 392, 427, 139, , 143
ESP10, 203, 298, 344, 396, 433, 141, , 145
ESP10, 203, 295, 342, 392, 433, 144, , 148
ESP10, 214, 306, 351, 400, 441, 146, , 150
ESP10, 222, 309, 352, 400, 442, 148, , 152
ESP10, 222, 309, 352, 400, 440, 151, , 155
ESP10, 223, 308, 353, 397, 441, 153, , 157
ESP10, 216, 298, 348, 388, 433, 155, , 159
ESP10, 224, 303, 355, 393, 439, 157, , 161
ESP10, 222, 303, 358, 392, 439, 160, , 164
ESP10, 227, 304, 360, 390, 439, 162, , 166
ESP10, 229, 308, 358, 395, 436, 164, , 168
ESP10, 239, 316, 366, 404, 443, 167, , 171
ESP10, 251, 321, 372, 404, 448, 169, , 173
ESP10, 243, 314, 363, 395, 438, 171, , 175
ESP10, 252, 319, 368, 400, 444, 174, , 178
ESP10, 244, 311, 360, 393, 441, 176, , 180
ESP10, 252, 316, 366, 397, 449, 178, , 182
ESP10, 247, 309, 362, 394, 445, 180, , 184
ESP10, 250, 310, 364, 394, 448, 183, , 187
ESP10, 253, 312, 365, 397, 450, 185, , 189
ESP10, 254, 317, 362, 397, 447, 187, , 191
ESP10, 252, 317, 364, 394, 443, 190, , 194
ESP10, 261, 327, 374, 405, 450, 192, , 196
ESP10, 256, 321, 368, 403, 446, 194, , 198
ESP10, 259, 320, 365, 402, 447, 196, , 200
ESP10, 257, 315, 360, 398, 443, 199, , 203
ESP10, 258, 314, 360, 401, 442, 201, , 205
ESP10, 258, 317, 366, 407, 442, 203, , 207
ESP10, 250, 304, 353, 398, 433, 206, , 210
ESP10, 239, 295, 342, 389, 424, 208, , 212
ESP10, 243, 298, 346, 390, 428, 210, , 214
ESP10, 238, 292, 340, 382, 421, 213, , 217
ESP10, 221, 273, 320, 364, 410, 215, , 219
ESP10, 223, 276, 326, 368, 415, 217, , 221
ESP10, 219, 272, 323, 363, 412, 219, , 223
ESP10, 227, 280, 334, 370, 420, 222, , 226
ESP10, 216, 264, 320, 356, 407, 224, , 228
ESP10, 189, 239, 292, 329, 384, 226, , 230
ESP10, 181, 232, 285, 320, 376, 229, , 233
ESP10, 179, 238, 286, 319, 377, 231, , 235
ESP10, 186, 250, 292, 327, 387, 233, , 237
ESP10, 187, 251, 296, 331, 392, 236, , 240
ESP10, 181, 242, 289, 323, 384, 238, , 242
ESP10, 187, 239, 294, 322, 383, 240, , 244
ESP10, 190, 239, 297, 324, 386, 242, , 246
ESP10, 192, 240, 304, 325, 388, 245, , 249
ESP10, 190, 242, 302, 324, 385, 247, , 251
ESP10, 182, 235, 293, 318, 377, 249, , 253
ESP10, 186, 233, 286, 314, 373, 252, , 256
ESP10, 199, 241, 291, 321, 379, 254, , 258
ESP10, 204, 241, 291, 319, 379, 256, , 260
ESP10, 216, 256, 301, 328, 390, 258, , 262
ESP10, 222, 258, 302, 332, 393, 261, , 265
ESP10, 217, 251, 297, 330, 389, 263, , 267
ESP10, 214, 248, 295, 332, 387, 265, , 269
ESP10, 219, 249, 299, 333, 388, 268, , 272
ESP10, 225, 255, 301, 334, 396, 270, , 274
ESP10, 222, 256, 298, 333, 395, 272, , 276
ESP10, 225, 260, 302, 335, 396, 275, , 279
ESP10, 232, 267, 310, 341, 398, 277, , 281
ESP10, 231, 272, 307, 337, 394, 279, , 283
ESP10, 225, 266, 304, 331, 392, 281, , 285
ESP10, 226, 267, 307, 332, 395, 284, , 288
ESP10, 217, 262, 300, 325, 389, 286, , 290
ESP10, 215, 268, 300, 324, 390, 288, , 292
ESP10, 215, 266, 303, 325, 390, 291, , 295
ESP10, 214, 267, 299, 327, 387, 293, , 297
ESP10, 217, 268, 297, 327, 385, 295, , 299
ESP10, 220, 263, 293, 328, 381, 297, , 301
ESP10, 218, 260, 292, 330, 377, 300, , 304
ESP10, 219, 259, 294, 332, 376, 302, , 306
ESP10, 218, 257, 294, 333, 373, 304, , 308
ESP10, 215, 260, 295, 330, 370, 307, , 311
ESP10, 218, 261, 295, 329, 371, 309, , 313
ESP10, 219, 264, 297, 327, 370, 311, , 315
ESP10, 218, 269, 296, 326, 370, 314, , 318
ESP10, 219, 271, 300, 328, 370, 316, , 320
ESP10, 220, 272, 300, 327, 372, 318, , 322
ESP10, 231, 282, 309, 334, 380, 320, , 324
ESP10, 239, 287, 312, 339, 381, 323, , 327
ESP10, 243, 294, 319, 343, 387, 325, , 329
ESP10, 243, 297, 320, 344, 387, 327, , 331
ESP10, 247, 299, 327, 348, 391, 330, , 334
ESP10, 246, 299, 326, 349, 391, 332, , 336
ESP10, 244, 295, 320, 345, 385, 334, , 338
ESP10, 247, 300, 325, 349, 388, 336, , 340
ESP10, 248, 304, 325, 352, 389, 339, , 343
ESP10, 253, 306, 325, 352, 392, 341, , 345
ESP10, 252, 310, 325, 353, 394, 343, , 347
ESP10, 252, 308, 326, 353, 393, 346, , 350
ESP10, 244, 298, 317, 344, 386, 348, , 352
ESP10, 238, 290, 310, 338, 379, 350, , 354
ESP10, 249, 293, 314, 342, 382, 353, , 357
ESP10, 257, 295, 315, 341, 381, 355, , 359
ESP10, 254, 293, 315, 339, 379, 357, , 361
ESP10, 252, 290, 312, 335, 375, 359, , 363
ESP10, 261, 300, 318, 344, 383, 362, , 366
ESP10, 263, 297, 317, 342, 379, 364, , 368
ESP10, 260, 295, 316, 341, 376, 366, , 370
ESP10, 262, 300, 319, 344, 376, 369, , 373
ESP10, 264, 304, 324, 345, 375, 371, , 375
ESP10, 259, 298, 319, 339, 369, 373, , 377
ESP10, 264, 300, 322, 343, 372, 375, , 379
ESP10, 261, 300, 321, 343, 368, 378, , 382
ESP10, 248, 288, 306, 331, 355, 380, , 384
ESP10, 249, 288, 306, 333, 354, 382, , 386
ESP10, 255, 294, 315, 339, 361, 385, , 389
ESP10, 245, 282, 306, 328, 350, 387, , 391
ESP10, 257, 290, 314, 335, 360, 389, , 393
ESP10, 252, 283, 308, 329, 358, 392, , 396
ESP10, 261, 291, 314, 334, 363, 394, , 398
ESP10, 258, 287, 311, 331, 360, 396, , 400
ESP10, 265, 292, 316, 337, 366, 398, , 402
ESP10, 269, 293, 317, 340, 365, 401, , 405
ESP10, 271, 295, 319, 342, 368, 403, , 407
ESP10, 271, 297, 322, 342, 368, 405, , 409
ESP10, 266, 294, 315, 336, 362, 408, , 412
ESP10, 264, 291, 310, 330, 356, 410, , 414
ESP10, 260, 283, 303, 322, 347, 412, , 416
ESP10, 263, 285, 306, 322, 346, 414, , 418
ESP10, 260, 281, 304, 320, 342, 417, , 421
ESP10, 253, 275, 298, 311, 334, 419, , 423
ESP10, 247, 269, 295, 306, 329, 421, , 425
ESP10, 242, 266, 289, 303, 324, 424, , 428
ESP10, 244, 269, 287, 304, 323, 426, , 430
ESP10, 233, 261, 277, 292, 312, 428, , 432
ESP10, 237, 264, 278, 293, 315, 431, , 435
ESP10, 221, 247, 261, 279, 302, 433, , 437
ESP10, 236, 261, 273, 292, 313, 435, , 439
ESP10, 235, 262, 273, 294, 313, 437, , 441
ESP10, 229, 257, 269, 289, 308, 440, , 444
ESP10, 226, 253, 264, 287, 302, 442, , 446
ESP10, 235, 260, 270, 293, 310, 444, , 448
ESP10, 230, 257, 266, 288, 307, 447, , 451
ESP10, 226, 252, 261, 282, 303, 449, , 453
ESP10, 224, 247, 258, 276, 300, 451, , 455
ESP10, 227, 249, 260, 278, 302, 453, , 457
ESP10, 223, 245, 260, 278, 299, 456, , 460
ESP10, 225, 245, 260, 279, 301, 458, , 462
ESP10, 227, 243, 260, 276, 298, 460, , 464
ESP10, 237, 249, 265, 278, 303, 463, , 467
ESP10, 238, 250, 266, 277, 302, 465, , 469
ESP10, 228, 241, 258, 271, 294, 467, , 471
ESP10, 225, 238, 256, 268, 291, 470, , 474
ESP10, 227, 243, 262, 276, 296, 472, , 476
ESP10, 227, 244, 262, 278, 296, 474, , 478
ESP10, 229, 247, 266, 284, 300, 476, , 480
ESP10, 232, 255, 270, 290, 303, 479, , 483
ESP10, 237, 258, 274, 293, 307, 481, , 485
ESP10, 244, 264, 281, 300, 314, 483, , 487
ESP10, 246, 270, 281, 301, 315, 486, , 490
ESP10, 245, 269, 279, 298, 313, 488, , 492
ESP10, 248, 274, 290, 303, 319, 490, , 494
ESP10, 248, 273, 292, 307, 319, 492, , 496
ESP10, 244, 269, 289, 304, 318, 495, , 499
ESP10, 243, 269, 288, 304, 317, 497, , 501
ESP10, 245, 275, 292, 307, 320, 499, , 503
ESP10, 244, 273, 290, 307, 319, 502, , 506
ESP10, 240, 267, 283, 299, 311, 504, , 508
ESP10, 235, 263, 280, 296, 307, 506, , 510
ESP10, 234, 262, 279, 296, 306, 509, , 513
ESP10, 239, 266, 286, 302, 313, 511, , 515
ESP10, 243, 269, 288, 303, 315, 513, , 517
ESP10, 243, 272, 283, 300, 310, 515, , 519
ESP10, 251, 283, 290, 307, 318, 518, , 522
ESP10, 251, 279, 287, 304, 315, 520, , 524
ESP10, 255, 282, 289, 308, 320, 522, , 526
ESP10, 251, 276, 289, 303, 316, 525, , 529
ESP10, 253, 278, 290, 306, 317, 527, , 531
ESP10, 255, 280, 293, 309, 320, 529, , 533
ESP10, 256, 282, 296, 311, 322, 531, , 535
ESP10, 257, 282, 298, 314, 323, 534, , 538
ESP10, 265, 291, 308, 322, 334, 536, , 540
ESP10, 263, 289, 306, 320, 333, 538, , 542
ESP10, 265, 290, 306, 322, 334, 541, , 545
ESP10, 264, 295, 306, 320, 335, 543, , 547
ESP10, 263, 294, 304, 317, 332, 545, , 549
ESP10, 265, 297, 308, 320, 333, 548, , 552
ESP10, 263, 298, 308, 319, 332, 550, , 554
ESP10, 264, 299, 309, 319, 332, 552, , 556
ESP10, 271, 303, 314, 327, 337, 554, , 558
ESP10, 274, 308, 319, 330, 341, 557, , 561
ESP10, 277, 309, 321, 334, 342, 559, , 563
ESP10, 278, 307, 320, 333, 341, 561, , 565
ESP10, 279, 305, 320, 332, 338, 564, , 568
ESP10, 283, 306, 320, 334, 338, 566, , 570
ESP10, 282, 305, 320, 333, 338, 568, , 572
ESP10, 283, 303, 320, 333, 340, 571, , 575
ESP10, 284, 302, 319, 332, 340, 573, , 577
ESP10, 286, 303, 320, 332, 339, 575, , 579
ESP10, 285, 303, 317, 331, 336, 577, , 581
ESP10, 282, 301, 314, 329, 334, 580, , 584
ESP10, 284, 302, 318, 328, 336, 582, , 586
ESP10, 282, 299, 315, 326, 334, 584, , 588
ESP10, 287, 299, 318, 327, 336, 587, , 591
ESP10, 287, 297, 317, 327, 335, 589, , 593
ESP10, 288, 300, 320, 329, 336, 591, , 595
ESP10, 291, 305, 322, 331, 340, 593, , 597
ESP10, 295, 308, 326, 336, 344, 596, , 600
ESP10, 290, 304, 321, 330, 341, 598, , 602
ESP10, 288, 302, 318, 327, 337, 600, , 604
ESP10, 292, 306, 319, 326, 336, 603, , 607
ESP10, 289, 304, 316, 323, 332, 605, , 609
ESP10, 290, 306, 316, 325, 333, 607, , 611
ESP10, 285, 301, 313, 320, 329, 610, , 614
ESP10, 285, 298, 311, 320, 327, 612, , 616
ESP10, 288, 302, 313, 322, 328, 614, , 618
ESP10, 292, 305, 315, 324, 332, 616, , 620
ESP10, 284, 298, 308, 317, 324, 619, , 623
ESP10, 291, 300, 312, 321, 327, 621, , 625
ESP10, 289, 298, 311, 319, 327, 623, , 627
ESP10, 290, 298, 310, 319, 328, 626, , 630
ESP10, 293, 301, 312, 325, 331, 628, , 632
ESP10, 294, 300, 309, 323, 330, 630, , 634
ESP10, 294, 303, 311, 322, 331, 632, , 636
ESP10, 301, 310, 315, 329, 335, 635, , 639
ESP10, 304, 313, 319, 331, 339, 637, , 641
ESP10, 305, 316, 320, 333, 340, 639, , 643
ESP10, 302, 314, 321, 332, 337, 642, , 646
ESP10, 311, 323, 331, 340, 345, 644, , 648
ESP10, 311, 323, 333, 341, 345, 646, , 650
ESP10, 319, 329, 338, 347, 352, 649, , 653
ESP10, 320, 326, 337, 346, 349, 651, , 655
ESP10, 321, 328, 337, 345, 349, 653, , 657
ESP10, 323, 329, 338, 347, 350, 655, , 659
ESP10, 323, 332, 339, 348, 351, 658, , 662
ESP10, 321, 329, 338, 345, 349, 660, , 664
ESP10, 321, 329, 339, 345, 349, 662, , 666
ESP10, 325, 334, 342, 349, 352, 665, , 669
ESP10, 326, 336, 345, 351, 354, 667, , 671
ESP10, 324, 335, 343, 349, 353, 669, , 673
ESP10, 325, 337, 345, 351, 354, 671, , 675
ESP10, 321, 333, 341, 347, 353, 674, , 678
ESP10, 332, 342, 350, 355, 362, 676, , 680
ESP10, 332, 342, 349, 355, 361, 678, , 682
ESP10, 333, 343, 349, 355, 362, 681, , 685
ESP10, 328, 337, 344, 350, 356, 683, , 687
ESP10, 328, 338, 346, 349, 355, 685, , 689
ESP10, 326, 336, 344, 346, 353, 688, , 692
ESP10, 330, 340, 348, 351, 356, 690, , 694
ESP10, 335, 342, 351, 353, 359, 692, , 696
ESP10, 333, 340, 348, 352, 356, 694, , 698
ESP10, 335, 340, 348, 353, 356, 697, , 701
ESP10, 334, 339, 348, 353, 355, 699, , 703
ESP10, 338, 343, 351, 356, 358, 701, , 705
ESP10, 345, 349, 356, 359, 362, 704, , 708
ESP10, 346, 349, 356, 359, 361, 706, , 710
ESP10, 346, 350, 356, 359, 361, 708, , 712
ESP10, 346, 350, 355, 359, 361, 710, , 714
ESP10, 347, 351, 357, 360, 361, 713, , 717
ESP10, 347, 352, 356, 360, 361, 715, , 719
ESP10, 346, 351, 355, 359, 361, 717, , 721
ESP10, 345, 350, 354, 358, 359, 720, , 724
ESP10, 344, 350, 354, 357, 358, 722, , 726
ESP10, 346, 352, 355, 359, 360, 724, , 728
ESP10, 345, 352, 356, 358, 360, 727, , 731
ESP10, 346, 352, 356, 358, 360, 729, , 733
ESP10, 347, 352, 356, 358, 360, 731, , 735
ESP10, 347, 353, 356, 358, 361, 733, , 737
Max Scale
Scale To Data
Scale To Last 45 Days
Show Min/Max Ensemble Volume
Show Tooltips Help
Overlay
ESP10
HEFS
ESP0
Data Files
/chpsesp/ensemble/watersupply/GCDW1W_SQIN.ESPF10.csv
GCDW1W_SQIN.ESPF0.csv|2026-07-18
GCDW1W_SQIN.ESPF10.csv|2026-07-18
GCDW1W_SQIN.ESPFM.csv|2026-07-18
APR-SEP
COLUMBIA - GRAND COULEE DAM
(
GCDW1
)
Forecasts for Water Year
2027
Official Water Supply
ESP with 10 Days QPF
Ensemble:
2026-07-18
Issued:
2026-07-18
Hide Forecast
Forecast
Period
Forecasts Are in KAF
30 Year
Average
(1991-2020)
90 %
50 %
%
Average
10 %
APR-SEP
47636
59693
97
76772
61483
APR-JUL
39686
49824
94
64448
52774
APR-AUG
44272
56094
96
72572
58186
JAN-SEP
53149
67506
96
84802
70457
JAN-JUL
45539
57239
93
72766
61749
OCT-SEP
59710
74792
95
93580
78842
Move the mouse over the desired "Forecast Period" to display a graph.
Max Scale
Scale To Data
Scale To Last 45 Days
Show Min/Max Ensemble Volume
Show Tooltips Help
Overlay
ESP10
Data Files
/chpsesp/ensemble/watersupply/GCDW1W_SQIN.ESPF10.csv
GCDW1W_SQIN.ESPF0.csv|2026-07-18
GCDW1W_SQIN.ESPF10.csv|2026-07-18
GCDW1W_SQIN.ESPFM.csv|2026-07-18
APR-SEP
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ESP10,ESPM,ESP0
ESP10,ESPM,ESP0
Last Forecast
