May 1, 2025 Spring and Summer Streamflow Forecasts
Upper Missouri Basin
The high elevation snow pack in the Upper Missouri Basin as of May 1
was below average. The snow pack in the St. Mary Basin was 89 percent,
and the Milk River Basin was 87 percent.
April precipitation across the Upper Missouri Basin was below average.
Basin precipitation summaries for the Missouri Basin include: Milk St. Mary,
72 percent; Milk Canada, 81 percent; Lower Milk, 89 percent; above Toston,
73 percent; Toston to Ft. Peck, 64 percent.
April 2025 Upper Missouri Mean Precip Oct-Apr WY2025 Upper Missouri Mean Precip
Stream flow in the Upper Missouri Basin is forecast to be
below average during the upcoming Spring and Summer.
The St. Mary River is forecast to have 50 percent of average
April-September flows. Runoff is expected to range around
82 percent of average for the Missouri Basin above Fort Peck,
Montana.
Upper Missouri May 1, 2025 Spring and Summer Streamflow Forecasts
Of the four major irrigation reservoirs in Montana; Lima
Reservoir had 105 percent average storage, Clark Canyon was
holding 106 percent of average water, Gibson Reservoir had 55
percent of average stored water, and Fresno Reservoir had
49 percent of average stored water.
Yellowstone Basin
The high elevation snow pack in the Yellowstone Basin was near average
on May 1. The snow pack in the Upper Yellowstone Basin was 101 percent
of average. The snow packs in the Wind, Bighorn, and Shoshone Basins were 100,
97, and 92 percent of average, respectively. The snow packs in the Tongue
and Powder basins were 112 and 75 percent of average, respectively.
Precipitation during April was above average. The upper Yellowstone River
Basin received 134 percent of average precipitation while the Lower
Yellowstone River Basin reported 127 percent of average. The Bighorn
Basin received 117 percent of average precipitation while the
Wind River Basin received 79 percent of average. The Little Bighorn -
Upper Tongue Basin received 136 percent of average and the Powder River
had 113 percent of average precipitation.
April 2025 Yellowstone Mean Precip Oct-Apr WY2025 Yellowstone Mean Precip
Forecast stream flow in the Yellowstone Basin is below average
for the upcoming Spring and Summer. Stream flow for the
Yellowstone River above Sidney, Montana is forecast to be about
79 percent of average. Flow in the Tongue Basin is expected to be
78 percent of average. Flows in the Powder River are expected
to be about 45 percent of average.
Monthend storage at Boysen Reservoir was 93 percent of average.
Stored water in Buffalo Bill Reservoir was 97 percent of average.
Monthend storage was 103 percent of average at Bighorn Reservoir.
Yellowstone May 1, 2025 Spring and Summer Streamflow Forecasts
Platte Basin
The high elevation snow pack in the Upper North Platte Basin was
79 percent of average on May 1. The snow pack in the North Platte
Basin below Seminoe Reservoir was 74 percent of average. The snow
pack in the South Platte Basin was 73 percent of average.
Precipitation during April in the Upper North Platte Basin was 52
percent of average. In the Lower North Platte Basin, precipitation
was 66 percent of average. The North Platte Plains below Guernsy
Reservoir had 37 percent. The South Platte Mountains had 40
percent whereas the Plains had 33 percent of average April
precipitation.
April 2025 Platte Mean Precip Oct-Apr WY2025 Platte Mean Precip
Stream flow in the Platte Basin is forecast to be below
average during the upcoming Spring and Summer. Runoff
for streams above Seminoe Reservoir are expected to be
about 78 percent of average. Streams in the South Platte
Basin above South Platte, Colorado can expect 68 percent
of average flow. For the remainder of the South Platte
basin, flows are expected near 82 percent.
Stored water in the South Platte Basin was 99 percent of average
on May 1.
North Platte Streamflow Fcst South Platte Streamflow Fcst
WATER SUPPLY FORECAST
NWS MISSOURI BASIN RIVER FORECAST CENTER
PLEASANT HILL MISSOURI
1027 CDT WEDNESDAY MAY 07, 2025
DATA CURRENT AS OF: MAY 01, 2025
MISSOURI/YELLOWSTONE/PLATTE RIVER BASIN FORECASTS
50% % 10% 90% AVG
FORECAST POINT PERIOD (KAF) AVG (KAF) (KAF) (KAF)
--------------------------------------------------------------------
Boysen Resvr Inflow Apr-Sep 388 54 694 233 720
SBDW4
Boysen Resvr Inflow Apr-Sep 843 95 1208 630 890
SBDW4N
Bighorn R at Kane Apr-Sep 644 65 1110 502 985
LVEW4
Bighorn R at Kane Apr-Sep 1340 93 1996 1023 1440
LVEW4N
Greybull R at Meeteetse Apr-Sep 142 72 233 107 196
MEEW4
Greybull R at Meeteetse Apr-Sep 142 69 233 107 205
MEEW4N
Buffalo Bill Resvr Inflow Apr-Sep 564 69 734 476 815
CDYW4
Buffalo Bill Resvr Inflow Apr-Sep 652 72 815 569 910
CDYW4N
Keyhole Resvr Inflow Apr-Sep 10 250 34 4 4
KEYW4
St. Mary R nr Babb Apr-Sep 328 71 392 291 460
SMYM8
St. Mary R nr Babb Apr-Sep 303 57 367 264 535
SMYM8N
St. Mary R at Intl Boundary Apr-Sep 342 88 425 294 390
SMBM8
St. Mary R at Intl Boundary Apr-Sep 316 48 400 269 660
SMBM8N
Milk R nr Western Crossing Apr-Sep 11 10 33 8 113
PDBM8
Milk R nr Western Crossing Apr-Sep 18 44 47 12 41
PDBM8N
Milk R nr Eastern Crossing Apr-Sep 16 7 106 8 215
ERNM8
Milk R nr Eastern Crossing Apr-Sep 48 43 166 28 112
ERNM8N
North Platte R nr Northgate Apr-Sep 145 59 235 85 245
NGTC2
North Platte R nr Northgate Apr-Sep 199 67 288 137 295
NGTC2N
Encampment R nr Encampment Apr-Sep 119 76 140 94 156
ECRW4
Encampment R nr Encampment Apr-Sep 128 77 148 103 166
ECRW4N
Rock Cr nr Arlington Apr-Sep 42 79 49 35 53
KCRW4
Rock Cr nr Arlington Apr-Sep 42 79 49 35 53
KCRW4N
Seminoe Resvr Inflow Apr-Sep 533 70 694 353 765
SETW4
Seminoe Resvr Inflow Apr-Sep 685 74 840 513 920
SETW4N
Laramie R nr Woods Landing Apr-Sep 38 35 69 20 108
WODW4
Laramie R nr Woods Landing Apr-Sep 75 53 106 55 142
WODW4N
Little Laramie R nr Filmore Apr-Sep 44 80 56 35 55
SMTW4
Little Laramie R nr Filmore Apr-Sep 47 82 58 37 57
SMTW4N
Antero Resvr Inflow Apr-Sep 13 93 17 10 14
ANRC2
Antero Resvr Inflow Apr-Sep 13 93 17 10 14
ANRC2N
Spinney Mountain Resvr Inflow Apr-Sep 40 70 58 33 57
SPYC2
Spinney Mountain Resvr Inflow Apr-Sep 35 78 52 27 45
SPYC2N
Elevenmile Canyon Resvr Inflow Apr-Sep 40 68 52 35 59
EVNC2
Elevenmile Canyon Resvr Inflow Apr-Sep 38 76 57 28 50
EVNC2N
Cheesman Lk Inflow Apr-Sep 48 48 64 37 100
CHEC2
Cheesman Lk Inflow Apr-Sep 63 68 98 43 93
CHEC2N
S Platte R at S Platte Apr-Sep 288 120 321 271 240
SPTC2
S Platte R at S Platte Apr-Sep 124 60 178 88 205
SPTC2N
Bear Cr at Morrison Apr-Sep 13 50 23 8 26
MRRC2
Bear Cr at Morrison Apr-Sep 13 50 23 8 26
MRRC2N
Clear Cr at Golden Apr-Sep 80 68 103 65 118
GLDC2
Clear Cr at Golden Apr-Sep 91 69 114 75 131
GLDC2N
St. Vrain Cr at Lyons Apr-Sep 48 61 70 38 79
LNSC2
St. Vrain Cr at Lyons Apr-Sep 72 66 99 59 109
LNSC2N
Boulder Cr nr Orodell Apr-Sep 16 34 26 14 47
OROC2
Boulder Cr nr Orodell Apr-Sep 29 56 43 25 52
OROC2N
S Boulder Cr nr Eldorado Sprgs Apr-Sep 20 57 25 15 35
BELC2
S Boulder Cr nr Eldorado Sprgs Apr-Sep 20 50 30 15 40
BELC2N
Cache La Poudre at Canyon Mouth Apr-Sep 115 106 170 90 108
FTDC2
Cache La Poudre at Canyon Mouth Apr-Sep 146 70 208 106 210
FTDC2N
Lima Resvr Inflow Apr-Sep 58 76 76 52 76
LRRM8
Lima Resvr Inflow Apr-Sep 58 73 76 52 79
LRRM8N
Clark Canyon Resvr Inflow Apr-Sep 45 41 53 43 110
CLKM8
Clark Canyon Resvr Inflow Apr-Sep 98 49 129 87 198
CLKM8N
Beaverhead R at Barretts Apr-Sep 109 55 122 105 199
BARM8
Beaverhead R at Barretts Apr-Sep 123 44 156 110 280
BARM8N
Ruby R Resvr Inflow Apr-Sep 50 57 63 41 88
ALRM8
Ruby R Resvr Inflow Apr-Sep 51 53 64 42 97
ALRM8N
Big Hole R nr Melrose Apr-Sep 477 80 663 413 595
MLRM8
Big Hole R nr Melrose Apr-Sep 546 83 731 480 660
MLRM8N
Hebgen Resvr Inflow Apr-Sep 432 93 491 387 465
HBDM8
Hebgen Resvr Inflow Apr-Sep 432 93 491 387 465
HBDM8N
Ennis Resvr Inflow Apr-Sep 609 85 708 568 715
ELMM8
Ennis Resvr Inflow Apr-Sep 717 98 825 652 730
ELMM8N
Gallatin R nr Gateway Apr-Sep 366 77 451 309 475
GLGM8
Gallatin R nr Gateway Apr-Sep 366 77 451 309 475
GLGM8N
Gallatin R at Logan Apr-Sep 417 83 543 350 505
LOGM8
Gallatin R at Logan Apr-Sep 570 88 685 511 650
LOGM8N
Missouri R at Toston Apr-Sep 1535 75 1980 1379 2060
TOSM8
Missouri R at Toston Apr-Sep 2315 82 2726 2150 2830
TOSM8N
Missouri R at Fort Benton Apr-Sep 1622 53 1856 1529 3060
FBNM8
Missouri R at Fort Benton Apr-Sep 3294 80 3891 2994 4100
FBNM8N
Missouri R nr Virgelle Apr-Sep 1775 52 2024 1653 3420
VRGM8
Missouri R nr Virgelle Apr-Sep 3657 80 4438 3350 4560
VRGM8N
Missouri R nr Landusky Apr-Sep 2086 57 2359 1892 3680
LDKM8
Missouri R nr Landusky Apr-Sep 4040 83 4823 3709 4890
LDKM8N
Missouri R below Fort Peck Dam Apr-Sep 2380 62 2705 2106 3840
FPKM8
Missouri R below Fort Peck Dam Apr-Sep 4366 84 5151 3992 5180
FPKM8N
Gibson Resvr Inflow Apr-Sep 328 73 448 280 450
AGSM8
Gibson Resvr Inflow Apr-Sep 328 73 448 279 450
AGSM8N
Marias R nr Shelby Apr-Sep 237 54 365 178 435
SHLM8
Marias R nr Shelby Apr-Sep 292 60 420 228 490
SHLM8N
Musselshell R at Harlowton Apr-Sep 31 39 58 22 80
HLWM8
Musselshell R at Harlowton Apr-Sep 42 44 67 31 95
HLWM8N
Yellowstone R at Yellowstone Lk Apr-Sep 389 48 429 334 815
YLOW4
Yellowstone R at Yellowstone Lk Apr-Sep 509 61 585 438 840
YLOW4N
Yellowstone R at Corwin Sprgs Apr-Sep 1300 66 1487 1136 1980
CORM8
Yellowstone R at Corwin Sprgs Apr-Sep 1482 72 1692 1294 2070
CORM8N
Yellowstone R at Livingston Apr-Sep 1310 57 1557 1184 2290
LIVM8
Yellowstone R at Livingston Apr-Sep 1738 71 2021 1534 2440
LIVM8N
Yellowstone R at Billings Apr-Sep 2509 62 3105 2251 4070
BILM8
Yellowstone R at Billings Apr-Sep 3595 75 4237 3273 4790
BILM8N
Yellowstone R at Miles City Apr-Sep 3590 61 4555 3139 5850
MILM8
Yellowstone R at Miles City Apr-Sep 6289 82 7601 5531 7690
MILM8N
Yellowstone R at Sidney Apr-Sep 3424 60 4365 2881 5710
SIDM8
Yellowstone R at Sidney Apr-Sep 6498 81 7877 5652 8060
SIDM8N
Boulder R at Big Timber Apr-Sep 181 54 220 151 335
BTMM8
Boulder R at Big Timber Apr-Sep 223 59 261 193 375
BTMM8N
Stillwater R nr Absarokee Apr-Sep 387 72 475 339 540
SRAM8
Stillwater R nr Absarokee Apr-Sep 447 75 533 399 595
SRAM8N
Clks Fk Yellowstone R nr Belfry Apr-Sep 457 74 564 397 620
BFYM8
Clks Fk Yellowstone R nr Belfry Apr-Sep 530 76 635 470 695
BFYM8N
Bighorn R nr St. Xavier Apr-Sep 960 67 1414 852 1430
STXM8
Bighorn R nr St. Xavier Apr-Sep 2223 90 2970 1767 2460
STXM8N
Little Bighorn R nr Hardin Apr-Sep 100 79 153 86 127
HRDM8
Little Bighorn R nr Hardin Apr-Sep 100 79 153 86 127
HRDM8N
Tongue R nr Dayton Apr-Sep 75 78 103 59 96
DAYW4
Tongue R nr Dayton Apr-Sep 81 80 108 64 101
DAYW4N
Tongue R nr Decker Apr-Sep 143 61 231 108 235
DSLM8
Tongue R nr Decker Apr-Sep 189 79 276 153 240
DSLM8N
Tongue R Resvr Inflow Apr-Sep 137 58 227 101 235
DKRM8
Tongue R Resvr Inflow Apr-Sep 183 75 273 147 245
DKRM8N
Powder R at Moorhead Apr-Sep 78 35 232 59 225
MHDM8
Powder R at Moorhead Apr-Sep 116 43 275 94 270
MHDM8N
Powder R nr Locate Apr-Sep 84 32 257 61 260
LOCM8
Powder R nr Locate Apr-Sep 141 46 331 106 305
LOCM8N
Locations with an `N` suffix indicate natural flows excluding
stream augmentations.
KAF: Thousands of Acre-feet
%AVG: Current 50%/AVG
AVG: Average(50%) seasonal runoff voulme as simulated by the river
forecast model considering acontinuous simulation of the basin
response to historic climate data (observed precipitation and
temperatures) over the period of 1991-2020.
The 50%, 10% and 90% columns indicate the probability that the
actual volume will exceed the forecast for the valid time period.
Beginning April 1, May and June official forecasts include observed
runoff volume up to official forecast date.
For more information, please visit: www.weather.gov/mbrfc/water
