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Visit for access to new EXPERIMENTAL products and services from the National Water Center: National Hydrologic Discussion, Area Hydrologic Discussion, Flood Hazard Outlook and the National Water Center Visualization Services, a suite of geospatial services depicting River Forecast Center and National Water Model information.

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Hydrograph River at a Glance Download
Fortymile River at South Fork Stage (ft)Observed: 82.7 ft at 10:00PM Mar 13, 2023Highest Observation: 83 ft at 4:00AM Mar 14, 2023Observed: 81.99 ft at 4:00PM Mar 19, 2023Observed: 82.07 ft at 10:00PM Mar 19, 2023Observed: 82.31 ft at 4:00AM Mar 20, 2023Observed: 82.35 ft at 10:00AM Mar 20, 2023FMSA2(plotting HGIRZ) Graph Created (12:02PM Mar 20, 2023)ObservedLatest observed value: 82.35 ft at 10:00 AM AKDT 20-Mar-2023. Flood Stage is 97 ft
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About this graph
Tabular Data (UTC)
Tabular Data (AKDT)
XML Data
RSS Files
Datum: Not Available
NOTE: NWS gage operated on a seasonal basis. No data available during winter months.

NOTE: Gage data do not meet the quality standards of USGS gages.

NOTE: Forecasts are not available for the Fortymile River at South Fork. Only observed stages are available for this point.

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Upstream Gauge - at West Fork Upstream Gauge Downstream Gauge Downstream Gauge - at Walker Fork
Flood Categories (in feet)
Major Flood Stage: 0
Moderate Flood Stage: 98
Flood Stage: 97
Action Stage: 91
Low Stage (in feet): -9999

Historic Crests

(P): Preliminary values subject to further review.

Recent Crests

(P): Preliminary values subject to further review.

Low Water Records
Currently none available.
Zoom Level:10
KML Image
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
If you notice any errors in the below information, please contact our Webmaster
97.62 Parking lot of boat launch become inundated.
97.39 Low spot on the bridge approach from the south. Water inundates the DOT maintenance camp. Minor flood stage.
92.69 High water mark from flooding in June of 2000.
87 Minor flood stage
86.2 Bankfull stage
(1) Bridge
(2) Downstream
(3) Upstream
(4) Fortymile River at South Fork looking upstream, Stage = 84.05 ft
(5) Fortymile River at South Fork looking downstream, Stage = 84.05 ft
About This Location Collapse

Latitude: 64.057778° N, Longitude: 141.830278° W, Horizontal Datum: NAD83/WGS84

River Stage
Reference Frame
Gauge Height Flood Stage Uses
NWS stage 0 ft 97 ft Interpreting hydrographs and NWS watch, warnings, and forecasts, and inundation maps
Vertical Datum Elevation
(gauge height = 0)
(gauge height = flood stage)
Elevation information source
NAVD88 1436.69 ft 1533.69 ft Survey grade GPS equipment, FEMA flood plain maps, newer USGS topographic maps
NGVD 29 Not Available Not Available Older USGS topographic maps, NGVD29 benchmarks
MSL Not Available Not Available Older USGS topographic maps, MSL benchmarks
Other Not Available Not Available  
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Long-term Hydrograph
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Hydrologic Resources Additional Resources
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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
National Weather Service
Fairbanks Weather Forecast Office
UAF-IARC Bldg. P.O. Box 757345
Fairbanks, AK 99775-7345
(907) 458-3700
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Page last modified: 2-Nov-2020 7:26 PM
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