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This probabilistic forecast is issued by the Northwest River Forecast Center.
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About this graph
Forecasts for the Okanogan River near Tonasket are issued routinely year-round.
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Upstream Gauge - at Oroville Upstream Gauge Downstream Gauge Downstream Gauge - at Malott
Zoom Level:11
Flood Categories (in feet)
Major Flood Stage: 18
Moderate Flood Stage: 17
Flood Stage: 15
Action Stage: 14
Low Stage (in feet): 3

Historic Crests
(1) 22.54 ft on 06/02/1972
(2) 21.79 ft on 05/31/1948
(3) 19.71 ft on 05/12/2018
(4) 18.79 ft on 06/19/1974
(5) 18.66 ft on 06/18/1950
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(P): Preliminary values subject to further review.

Recent Crests
(1) 14.40 ft on 05/07/2023 (P)
(2) 14.15 ft on 06/07/2022
(3) 15.48 ft on 11/17/2021
(4) 15.81 ft on 06/02/2020
(5) 11.71 ft on 05/18/2019
Show More Recent Crests

(P): Preliminary values subject to further review.

Low Water Records
(1) 3.43 ft on 09/05/1931
(2) 4.20 ft on 09/01/2021
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Gauge LocationGauge Map Marker
Latitude/Longitude Disclaimer: The gauge location shown in the above map is the approximate location based on the latitude/longitude coordinates provided to the NWS by the gauge owner.
Flood Impacts & Photos Collapse
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22 Severe flooding of surrounding cropland is likely. Damage is possible to numerous homes, outbuildings, irrigation systems and roads adjacent to the river. Water will be over Highway 97 near Ellisford and other areas between Tonasket and Oroville.
19.5 Buildings along the river on Brooks Tract Road in East Omak will be flooded and utilities will be impacted.
19 Water may be into homes along the river in and near Tonasket. Water will start to come over the banks at Brooks Track Rd in East Omak.
18 Water will be approaching homes along the river in and near Tonasket. Major flooding of surrounding cropland is likely. Some homes and buildings adjacent to the river will experience some basement and first floor flooding.
17 Low lying fields and pasture land in the flood plain along the Okanogan river valley, from Oroville to Okanogan, will be flooded. Some homes near the river in Okanogan may experience some basement flooding from seepage. Water will be between the railroad and Highway 97 near Ellisford to south Oroville. Water will be against the shoulder of Omak River Road across from Wanacut Creek.
16 Pasture land between Rodeo Track Road and Benton Street, on the east side of the river near Omak, will begin to flood. Flooding increases between Tonasket and Oroville.
15.5 Minor flooding in low lying areas and pasture lands is likely from Omak to Tonasket, especially near Ellisford.
15 Minor flooding of low lying areas and pasture lands is possible between Highway 7 and 97 from Oroville to Riverside.
Low Water Impacts Collapse
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600 cfs Minimum base flow for August 15 and September 1st & 15th at this river gage, which is the lowest base flow of the year. The affected stream reach is from the confluence of Chewiliken Creek to confluence of Similkameen River. Water-rights junior to the base flows established in the rule may be restricted if streamflow drops below this value. For more information on this and the minimum base flows for other times in the year and for other reaches, refer to Washington Administrative Code (WAC) Chapter 173-549.

Other Real-time and/or Archive Data Sources:

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The National Weather Service prepares its forecasts and other services in collaboration with agencies like the US Geological Survey, US Bureau of Reclamation, US Army Corps of Engineers, Natural Resource Conservation Service, National Park Service, ALERT Users Group, Bureau of Indian Affairs, and many state and local emergency managers across the country. For details, please click here.
NWS Information
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2601 N. Rambo Rd.
Spokane, WA 99224
(509) 244-0110
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Page last modified: 2-Nov-2020 7:27 PM
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