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Idaho river flow

13,870 cfs

Mean flow of the Snake River at Weiser over the calendar year, 2025

+1.5% since 2024 (13,670 cfs); +34.4% since 2015 (10,320 cfs)

Source: U.S. Geological Survey, USGS Surface-Water Annual Statistics, Idaho streamgages. Data period 2025.

Mean discharge over the calendar year at a USGS stream gage.

Change and comparison

From 1911 (22,110 cfs) to 2025 (13,870 cfs), the change was −37.3%.

Over the most recent 5 years, 2020 (12,510 cfs) to 2025 (13,870 cfs), the change was +10.9%.

The series high is 33,520 cfs in 1984 and the low is 8,429 cfs in 1992.

The largest category is Snake River at Weiser at 13,670 cfs; next is Kootenai River at Porthill (total flow) at 12,250 cfs.

Historical data

Idaho river flow, 1911 to 2025Idaho river flow, 1911 to 2025. Snake River at Weiser: 22,110 in 1911, 13,870 in 2025.010k20k30k40k19502000Snake Riverat WeiserCubic feet per secondIdaho river flow, 1911 to 2025Idaho river flow, 1911 to 2025. Snake River at Weiser: 22,110 in 1911, 13,870 in 2025.010k20k30k40k19502000Snake River atWeiserCubic feet per secondIdaho river flow, 1911 to 2025Idaho river flow, 1911 to 2025. Snake River at Weiser: 22,110 in 1911, 13,870 in 2025.010k20k30k40k192019401960198020002020Snake River atWeiserCubic feet per second

Source: U.S. Geological Survey, USGS Surface-Water Annual Statistics, Idaho streamgages.

Data table (115 rows)
PeriodSnake River at Weiser (cubic feet per second)
191122,110
191223,840
191322,610
191422,470
191513,210
191624,290
191725,470
191819,850
191915,920
192015,650
192125,250
192221,140
192318,080
192411,060
192521,400
192612,590
192722,890
192821,310
192914,740
193012,800
193110,210
193215,910
193313,590
193410,390
193511,250
193615,800
193712,500
193820,480
193913,710
194014,880
194114,440
194217,020
194326,820
194414,070
194517,720
194621,460
194717,160
194817,200
194917,040
195019,840
195122,660
195225,770
195318,460
195416,360
195514,040
195621,840
195721,190
195819,110
195913,780
196014,250
196111,350
196214,460
196315,620
196417,700
196525,300
196613,650
196714,130
196813,630
196920,160
197019,730
197130,440
197226,660
197315,820
197425,030
197523,580
197622,760
19779,995
197817,100
197914,250
198016,900
198114,860
198227,350
198331,520
198433,520
198518,470
198628,280
198711,940
198810,110
198913,950
199010,790
199110,380
19928,429
199316,530
199410,780
199517,550
199624,610
199731,980
199823,010
199922,910
200015,120
20019,823
200211,030
200311,650
200410,940
200511,060
200621,430
200710,860
200812,580
200914,320
201013,330
201124,880
201215,820
20139,818
201411,240
201510,320
201612,150
201725,310
201816,250
201917,000
202012,510
202110,090
202210,140
202312,980
202413,670
202513,870

Flow by gage

Cubic feet per second

  1. Kootenai River at Porthill (total flow)12,250.0
  2. Clearwater River at Spalding11,150.0
  3. Salmon River at White Bird9,077.0
  4. Snake River at King Hill7,818.0
  5. Snake River near Heise6,702.0
  6. Snake River near Twin Falls1,690.0
  7. Snake River near Kimberly1,545.0
  8. Snake River at Milner (total flow)1,263.0
  9. Boise River near Twin Springs966.7
  10. Boise River at Glenwood Bridge near Boise923.4
  11. Bear River at Pescadero405.0

Source: U.S. Geological Survey, USGS Surface-Water Annual Statistics, Idaho streamgages. Data period 2024.

Data table (11 rows)
Gage2024 (cfs)
Kootenai River at Porthill (total flow)12,250.0
Clearwater River at Spalding11,150.0
Salmon River at White Bird9,077.0
Snake River at King Hill7,818.0
Snake River near Heise6,702.0
Snake River near Twin Falls1,690.0
Snake River near Kimberly1,545.0
Snake River at Milner (total flow)1,263.0
Boise River near Twin Springs966.7
Boise River at Glenwood Bridge near Boise923.4
Bear River at Pescadero405.0

Flow by gage over time

Flow by gage over timeFlow by gage over time. 8 series. Kootenai River at Porthill (total flow): 10,950 in 1929, 11,600 in 2025.010k20k30k19502000KootenaiRiver atPorthill(totalflow)ClearwaterRiver atSpaldingSalmonRiver atWhite BirdSnake Riverat KingHillCubic feet per secondFlow by gage over timeFlow by gage over time. 8 series. Kootenai River at Porthill (total flow): 10,950 in 1929, 11,600 in 2025.010k20k30k19502000Kootenai Riverat Porthill(total flow)ClearwaterRiver atSpaldingSalmon Riverat White BirdSnake River atKing HillSnake Rivernear HeiseSnake Rivernear KimberlyCubic feet per secondFlow by gage over timeFlow by gage over time. 8 series. Kootenai River at Porthill (total flow): 10,950 in 1929, 11,600 in 2025.010k20k30k192019401960198020002020Kootenai Riverat Porthill(total flow)Clearwater Riverat SpaldingSalmon River atWhite BirdSnake River atKing HillSnake River nearHeiseSnake River nearKimberlySnake River atMilner (totalflow)Boise River nearTwin SpringsCubic feet per second

Source: U.S. Geological Survey, USGS Surface-Water Annual Statistics, Idaho streamgages.

Source

Organization
U.S. Geological Survey
Dataset
USGS Surface-Water Annual Statistics, Idaho streamgages
Geography
Twelve USGS stream gages on the Snake, Boise, Salmon, Clearwater, Kootenai and Bear rivers in Idaho
Time coverage
1910-2025 (varies by gage)
Update frequency
Annual
Original file
https://waterservices.usgs.gov/nwis/stat/
Methodology
https://help.waterdata.usgs.gov/faq/about-statistics
License
Public domain. U.S. federal government work.
Our copy
USGS Surface-Water Annual Statistics, Idaho streamgages

Caveats

  • Each figure is the mean of daily mean discharge over a calendar year, in cubic feet per second, as computed by USGS's own annual statistics service from approved (not provisional) daily readings.
  • USGS's own convention for an annual streamflow figure is the water year, 1 October to 30 September; this dataset stores calendar years instead so the series lines up with every other year on this site.
  • At Milner and at Porthill the figure is USGS's "total flow" statistic, which adds diverted or bypassed water back to the channel reading, so those two are not directly comparable to a plain gage reading elsewhere on the same river.
  • Shoshone Falls sits on the Snake River between the Kimberly and Twin Falls gages; the Kimberly gage is the closest gage upstream of the falls and the Twin Falls gage the closest downstream. Milner Dam, upstream of both, diverts most or all of the river's flow for irrigation in the growing season, so neither gage's reading is a measurement of flow over the falls.

Cite

Cite this page as Understand Idaho, “Idaho river flow”, https://understandidaho.com/water/river-flow/, retrieved on the date you read it, and the publisher named above for the figures themselves. The dataset behind it is described in the data catalog.

This page was last updated .