Floodplains & Models

Find flooding reference information here.

Clean Water Services has worked with the Federal Emergency Management Services and Washington County to gather data on floodplains in Washington County. The models referenced below represent the best available information on the location, water surface elevation and cubic feet per second of peak stream flows. Watersheds 2000 Hydrologic Modeling (PDF, 4.28MB) information was created using NGVD29 datum. 

This data was created for the floodplain update project and was submitted to FEMA in 2006. While these maps may help developers and others locate floodplains, they are not to be used to determine whether property owners need flood insurance and are not final. Go to fema.gov for more information.

The models are developed for use by engineers and can be viewed using free software, HEC-RAS or HEC-HMS, from the US Army Corps of Engineers.

Hydrology & Hydraulics Models contain projected 2, 5, 10, 25, 50, 100, & 500 year flows.

(HEC-RAS Models)

Existing & Future Hydrology
(HEC-HMS Models)

Beaverton East
Bethany East
Bronson East
Butternut East


Future Hydrology Cedar
Cedar Mill - North Johnson CM Update
Celebrity East

Future Hydrology Chicken
Council Dairy
Dairy Dairy
Dawson East
Erickson East
Fanno Fanno
Hall East
Hedges Hedges
Future Hydrology Hedges
Holcomb East
Johnson South East
Lake Oswego  
McKay Dairy
Nyberg Nyberg
Future Hydrology Nyberg
Rock East
Rock South Rock South
Future Hydrology Rock South
Storey Dairy
Tualatin Lower  
Tualatin Upper  
Turner East
Waible Dairy
Willow East

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