Written by: Paige Gordichuk, S.M.ASCE and Rollin H. Hotchkiss, Ph.D., P.E., BC.WRE, F.ASCE, Brigham Young University

A low head dam on the Jordan River Supply Canal, Utah. The upstream flow appears smooth and tranquil, which does not alert recreationalists to the hazard below.

Low head dams are structures built across a river or stream that allow water to flow continuously and uncontrolled over the crest1 and are generally between 6 inches and 25 feet high. They represent an important public safety issue because recreationalists can be deceived by the smooth and tranquil appearance dam’s upstream pool (Figure 1, left). 

Once over the crest, the recreationalist risk being caught in a recirculating current if a submerged hydraulic jump occurs (Figure 2, below). Awareness about the dangers of low head dams has been increasing in the past decade due to the increase in online information (2,3).

In 2015, Brigham Young University published a website to increase awareness about low head dams. The website has been updated in 2025 with the same goal to increase awareness and provide information for water resources professionals and state legislatures.

An illustration of the submerged hydraulic jump.

The new website is run through google products and hosted on git hub pages. It includes an interactive map to view low head dam sites where fatalities have occurred, a searchable list of low head dams and their incidents, a statistics bar with total numbers for fatalities and sites, and a google form for users to report incidents (Figure 3, below). 

A screenshot of the interactive map and statistics on www.lowheaddamfatalities.org

The website is searchable by state, county, city, name of dam, river, date of incident, and incident description, allowing users to find information pertinent to their needs and local area. The website can be found at www.lowheaddamfatalities.org. In addition to the fatalities database website, the ASCE-EWRI hosts the national inventory of low head dams. This vital resource showcases over 13,500 low head dams and is a tool for engineers, researchers, and recreationalists alike.

References/image sources:
1 - Federal Register. 2017. Vol 82(4): 1997
2 -  https://trends.google.com/trends/explore?date=all&geo=US&q=low%20head%20dam accessed 23 July 2025.
3 - Kern, Edward W., Rollin H. Hotchkiss, and Daniel P. Ames. "Introducing a low‐head dam fatality database and internet information portal." JAWRA Journal of the American Water Resources Association 51.5 (2015): 1453-1459.