In the U.S. more people have drowned at low-head dams in the last 50 years than from all the large dam failures during the same time period
Low-head dams — man-made barriers just a few feet tall that change the level of a river — are commonly referred to as “drowning machines.” And while they may look harmless, they didn’t garner the nickname by happenstance.
BYU research finds that more than 1,000 people have drowned because of low-head dams. In a massive effort to prevent future tragedies, BYU professor Rollin Hotchkiss created a national task force, and with the help of BYU students, built the first nationwide database cataloging the location of more than 13,000 low-head dams.
“The heart-rending stories of families impacted by drownings at low-head dams motivated me to do something to help,” said Hotchkiss, a BYU professor of civil engineering and the force behind the three-year project to build the database. “It doesn’t have to happen.”
Hotchkiss, with the support of four task force co-chairs, unveiled the national inventory of low-head dams at the Dam Safety Conference of the Association of State Dam Safety Officials this September.
From upstream, it is nearly impossible to tell that a hazardous low-head dam looms ahead. These dams, including one located inconspicuously behind the Provo Deseret Industries, spread the entire width of the water way, so the horizon appears uninterrupted and unremarkable to nearby recreationalists — often until it’s too late.
As the name suggests, low-head dams are known for their short stature, but their height can range anywhere from 1 foot to 15 feet. When water levels are high, swift, strong currents can form at the base of these dams that force people under and trap them underneath the surface. About 25% of deaths happen when people attempt to rescue someone and underestimate the current.
“More people have drowned at low-head dams in the last 50 years than from all the large dam failures in the same period,” Hotchkiss said. “Low-head dams can be extremely dangerous, and they rarely get inspected or updated.”
Often, low-head dams are “orphaned,” meaning that no one owns or maintains them. These dams were created to maintain a steady water level to divert water for water supply, power production, or for local irrigation. If the low-head dam is no longer in use, it is difficult to determine ownership and accountability. Hotchkiss had to be creative in his methods to create the national database.
Hotchkiss started by asking a subcommittee of the national task force to reach out to state governments for their records, but only about a dozen had lists of low-head dams. The next step? Recruiting students to canvas Google Earth Pro for a white line across a river or stream — the tell-tale sign of whitewater on the downstream side of a low-head dam. Students then rated their confidence about a potential dam before it was reviewed by an expert, Bruce Rogers, a retired U.S. Army Corps Engineer who donated countless hours of time to the project.
“This is the opportunity that students long to have: being able to contribute to a meaningful project and leave an impact,” said, sophomore civil engineering student, Easton Cluff. “The Army Corps of Engineers will be using our beta catalog of low-head dams for years to come.”
Another group, the Southeast Aquatic Resources Partnership, shared their research on water obstructions with BYU, adding thousands of new locations for students to verify. Combining all their data resulted in locating 13,000-plus low-head dams across the country.
“This database couldn’t have been created without a lot of people’s help and goodwill,” Hotchkiss said. “We know there are more low-head dams, but this is a great place to start.”
In addition to the nationwide database, Hotchkiss has created an inventory of fatalities that have occurred at low-head dams, as well as multiple designs that could potentially reduce dangerous current strength.
To access the database, click this link: https://sarp.maps.arcgis.com/apps/webappviewer/index.html?id=1cab6b600069461da86a416173a585b2
