Skip Navigation Link  
NOAA logo - Click to go to the NOAA homepage National Weather Service NWS logo - Click to go to the NWS homepage
Advanced Hydrologic Prediction Service
Image background of Navigation bar Left
Bookmark and Share Navigation Bar End Cap


Web Portal Changes: The Advanced Hydrologic Prediction Service (AHPS) hosted at will be replaced by the National Water Prediction Service (NWPS), with a target of Spring 2024. Existing AHPS content and features will be preserved and expanded within NWPS. The NWS is now accepting feedback on NWPS. Please visit for more information.

Experimental National Water Center Products: Flood Inundation Mapping services are now available for 10% of the U.S. population. Please visit for more information. The National Hydrologic Discussion, Area Hydrologic Discussion, Flood Hazard Outlook, and real-time geospatial services depicting River Forecast Center and National Water Model forecasts, continue to be accessible via the URL above, as described in the StoryMap here.

DID YOU KNOW... Please try our new TEST hydrograph page link at: - Just replace “abcde” with your local hydrograph five character ID found in the lower left corner of the hydrograph.  In late March of 2024, the base URL path will become  Feedback can be provided HERE

Hydrograph River at a Glance Download
Fortymile River at South Fork Stage (ft)Observed: 81.13 ft at 9:00PM Nov 30, 2023Observed: 81.12 ft at 3:00AM Dec 01, 2023Observed: 81.14 ft at 9:00AM Dec 01, 2023Highest Observation: 81.17 ft at 3:00PM Dec 01, 2023Observed: 81.14 ft at 9:00PM Dec 01, 2023Observed: 81.14 ft at 3:00AM Dec 02, 2023Observed: 81.05 ft at 9:00AM Dec 02, 2023Observed: 81.04 ft at 9:00AM Dec 03, 2023Observed: 80.87 ft at 3:00PM Dec 03, 2023Observed: 80.69 ft at 9:00PM Dec 03, 2023Observed: 81.05 ft at 9:00AM Dec 04, 2023Observed: 81.08 ft at 3:00PM Dec 04, 2023Observed: 81.13 ft at 10:00PM Dec 04, 2023Observed: 81.01 ft at 3:00AM Dec 05, 2023Observed: 81.13 ft at 9:00AM Dec 05, 2023Observed: 81.1 ft at 3:00PM Dec 05, 2023FMSA2(plotting HGIRZ) Graph Created (3:19PM Dec 7, 2023)ObservedLatest observed value: 81.1 ft at 3:00 PM AKST 5-Dec-2023. Flood Stage is 97 ft
Printable Image
About this graph
Tabular Data (UTC)
Tabular Data (AKST)
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.

Return to Area Map
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  
Additional Information Collapse
Long-term Hydrograph
Resources Collapse
Hydrologic Resources Additional Resources
Collaborative Agencies Collapse
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
Ask Questions/Webmaster
Page last modified: 2-Nov-2020 7:26 PM
Privacy Policy
About Us
Career Opportunities