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Hydrograph River at a Glance Download
Tonsina River at Richardson Hwy Bridge Stage (ft)Observed: 8.4 ft at 10:00AM Apr 14, 2024Observed: 8.44 ft at 4:00PM Apr 14, 2024Observed: 8.41 ft at 10:00PM Apr 14, 2024Highest Observation: 8.51 ft at 4:00AM Apr 15, 2024Observed: 8.27 ft at 10:00AM Apr 15, 2024Observed: 8.2 ft at 4:00PM Apr 15, 2024Observed: 8.27 ft at 10:00PM Apr 15, 2024Observed: 8.34 ft at 4:00AM Apr 16, 2024Observed: 8.23 ft at 10:00AM Apr 16, 2024Observed: 8.22 ft at 4:00PM Apr 16, 2024Observed: 8.27 ft at 10:00PM Apr 16, 2024Observed: 8.28 ft at 4:00AM Apr 17, 2024Observed: 8.23 ft at 10:00AM Apr 17, 2024Observed: 7.79 ft at 4:00PM Apr 17, 2024Observed: 8.21 ft at 10:00PM Apr 17, 2024Observed: 7.95 ft at 4:00AM Apr 18, 2024Observed: 8.23 ft at 10:00AM Apr 18, 2024Observed: 8.06 ft at 4:00PM Apr 18, 2024Observed: 8.12 ft at 5:00AM Apr 19, 2024Observed: 7.82 ft at 4:00PM Apr 19, 2024Observed: 7.92 ft at 10:00PM Apr 19, 2024Observed: 7.93 ft at 6:07AM Apr 20, 2024Observed: 7.48 ft at 10:00AM Apr 20, 2024Observed: 7.72 ft at 4:00PM Apr 20, 2024Observed: 7.65 ft at 10:00PM Apr 20, 2024Observed: 7.61 ft at 4:00AM Apr 21, 2024TONA2(plotting HGIRZ) Graph Created (6:32AM Apr 21, 2024)ObservedLatest observed value: 7.61 ft at 4:00 AM AKDT 21-Apr-2024. Flood Stage is 12.5 ft
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About this graph
Tabular Data (UTC)
Tabular Data (AKDT)
XML Data
RSS Files
Datum: Not Available
NOTE: Stage may be affected by ice.

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

NOTE: Forecasts for the Tonsina River at Richardson Hwy Bridge are issued routinely during the warm season, and as needed at other times of the year.

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Flood Categories (in feet)
Major Flood Stage: 0
Moderate Flood Stage: 13
Flood Stage: 12.5
Action Stage: 11.5
Low Stage (in feet): -9999

Historic Crests
(1) 14.57 ft on 10/11/2006 (P)
(2) 13.44 ft on 06/30/2000
(3) 13.23 ft on 06/25/2001
(4) 13.00 ft on 09/22/1995
(5) 13.00 ft on 06/09/1998
Show More Historic Crests

(P): Preliminary values subject to further review.

Recent Crests
(1) 10.50 ft on 06/21/2021
(2) 10.27 ft on 06/12/2017 (P)
(3) 10.59 ft on 06/21/2016 (P)
(4) 12.15 ft on 06/25/2012 (P)
(5) 10.88 ft on 06/05/2011
Show More Recent Crests

(P): Preliminary values subject to further review.

Low Water Records
Currently none available.
Zoom Level:11
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
25.5 Bridge Low Cord
12 High water level -- Class IV whitewater in Tonsina River canyon
11.5 Bankfull -- stage associated with a flow (5100 cfs) having a recurrence interval of ~2 years
10 Medium water level -- Class III+ whitewater in Tonsina River canyon
9 Low water level -- Class III whitewater in Tonsina River canyon
(1) Looking Downstream
(2) Looking Upstream
(3) Flood 10/10/2006
(4) Flood 10/10/2006
(5) Flood 10/10/2006
(6) Bridge
(7) Downstream left bank stage 9.96ft
(8) Downstream right bank stage 9.96ft
About This Location Collapse

Latitude: 61.661389° N, Longitude: 145.183889° W, Horizontal Datum: NAD83/WGS84

River Stage
Reference Frame
Gauge Height Flood Stage Uses
NWS stage 0 ft 12.5 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 Not Available Not Available Survey grade GPS equipment, FEMA flood plain maps, newer USGS topographic maps
NGVD 29 1500 ft 1513.5 ft 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
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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
Anchorage Weather Forecast Office
6930 Sand Lake Road
Anchorage, AK 99502
(907) 266-5105
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