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Web Portal Changes: In Spring 2024, the Advanced Hydrologic Prediction Service (AHPS) hosted at will be replaced by the National Water Prediction Service (NWPS) at a repurposed A preview of NWPS is available here, where you can see your station hydrograph by replacing SSSSS with the station 5-character id:

Flood Inundation Mapping: Experimental real-time flood Inundation mapping services for 10% of the United States are now available via the NWS Map Viewer. Additional products and geospatial services depicting River Forecast Center and National Water Model forecasts continue to be accessible as described in the StoryMap here.

Please visit for more information.

Hydrograph River at a Glance Download
Little Sioux River near Montgomery Stage (ft)Iowa Flood CenterMLSI4(plotting HGIRP) Graph Created (7:04PM Mar 4, 2024)Flood Stage is 1391 ft
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About this graph
Tabular Data (UTC)
Tabular Data (CST)
XML Data
RSS Files
Datum: NAVD88
NOTE: No forecasts are available for this location

NOTE: Gauge reading may be affected by ice.

NOTE: Forecasts are not available for the Little Sioux River near Montgomery. Only observed stages are available for this point.

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Downstream Gauge Downstream Gauge - near Milford
Flood Categories (in feet)
Major Flood Stage: 1394.5
Moderate Flood Stage: 1393
Flood Stage: 1391
Action Stage: 1390
Low Stage (in feet): -9999

Historic Crests
(1) 1,394.90 ft on 06/24/2018
(2) 1,394.32 ft on 03/16/2019
(3) 1,391.43 ft on 03/07/2020
(4) 1,390.13 ft on 04/15/2018
(5) 1,389.92 ft on 03/26/2023

(P): Preliminary values subject to further review.

Recent Crests
(1) 1,389.92 ft on 03/26/2023
(2) 1,391.43 ft on 03/07/2020
(3) 1,394.32 ft on 03/16/2019
(4) 1,394.90 ft on 06/24/2018
(5) 1,390.13 ft on 04/15/2018

(P): Preliminary values subject to further review.

Low Water Records
Currently none available.

For more information on your flood risk go to

Zoom Level:16
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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
If you notice any errors in the below information, please contact our Webmaster
1397 the bridge on 140th Street west of Montgomery is overtopped.
1396.5 140th Street west of Montgomery begins to flood.
1395 190th Avenue south of the MN/IA State Line begins to flood, and the bridge on 170th Avenue north of Highway 9 is overtopped. Water also reaches the bottom of the bridge on 140th Street west of Montgomery.
1394.5 Highway 9 east of the Little Sioux River bridge is flooded in two lower spots.
1393 water begins to flood 190th Avenue north of Montgomery.
1391.5 170th Avenue north of Highway 9 begins to flood.
1391 crop and pasture land begin to flood.
(1) upstream view
(2) at gage
(3) downstream view
About This Location Collapse

Latitude: 43.459518° N, Longitude: 95.230817° W, Horizontal Datum: NAD27

River Stage
Reference Frame
Gauge Height Flood Stage Uses
NWS stage 0 ft 1391 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 0.00 1391.00 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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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
Sioux Falls Weather Forecast Office
26 Weather Lane
Sioux Falls, SD 57104-0198
(605) 330-4247
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Page last modified: 2-Nov-2020 7:29 PM
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