As dam failures and incidents occur both nationally and internationally, there is a pressing need to understand the underlying causes for failure to help minimize such occurrences in the future. Current information on historical dam incidents is scattered, incomplete, missing, and sometimes misleading – making it difficult for owners and practitioners to easily access meaningful information that could assist them with critical design and operational decisions.  If lessons learned and best practices are not effectively communicated, there is a possibility that poor practices will be repeated and preventable incidents will not be averted.

Presented within are links to individual case studies as well as lessons learned pages that summarize historical dam incidents and failures and the valuable information gleaned from them.  Each page contains background and description, photographs, videos, best practices, and other resources related to the case study or lessons learned being addressed.  The contents of this webpage encompass a range of failure modes, dam types, and dam safety topics including best practices regarding engineering and design practices, human factors, emergency planning and response, operation and maintenance, and regulatory issues. 

The first new studies of 2021 have been uploaded with more currently being researched. The site now has more than 30 case studies and more than 20 lessons learned, as well as 5 ASDSO webinars that can be viewed free of charge as part of a Cooperating Technical Partnership between FEMA’s National Dam Safety Program and ASDSO.


February 2021

Case Study: Columbia River Levees (Oregon, 1948). Case Study: Columbia River Levees (Oregon, 1948).
Researcher: Meghan Walter
Reviewer: Steve Durgin
On May 30, 1948, rising floodwaters of the Columbia River breached a railroad fill acting as a levee and flooded the city of Vanport, Oregon. At the time, Vanport was Oregon’s second largest city and World War II’s largest federal housing project. Located in the marsh between the Columbia River and the Columbia slough, a system of levees protected Vanport from the floods of the Columbia River. At 4:17 pm on May 30th, Memorial Day 1948, a railroad embankment on the western end of the levee system collapsed under the pressure from the river, sending waves of water into Vanport. In less than a day, the nation’s largest housing project – and Oregon’s second largest city – was destroyed and 18,000 residents were displaced from their homes. Following the flood, the city was not rebuilt. The area is now home to a golf course, the Portland International Raceway, and recreational wetland areas. 

Lesson Learned: Floods can occur due to unusual or changing hydrologic conditions.
Researcher: Everett Taylor
Reviewer: Gregory Richards
Floods can trigger a significant response from dam owners and operators. The events caused by flooding may range from needing to pass large flows to overtopping and possible failure of the dam. Consequently, dam owners are tasked with monitoring weather patterns and runoff to effectively operate their facilities during hydrologic events. Unusual or changing conditions in the watershed, however, may result in larger than expected runoff events that can surprise owners and operators. These conditions may include rain on snow events, frozen or saturated ground, burned watersheds, and more. In addition to tracking weather and runoff predictions, dam owners and operators should be aware of the conditions in their contributing watersheds and consider the effects those conditions may have on runoff to their dams and reservoirs.