Low-head dams, such as the 8-foot-high structure at Duke Energy’s Dan River Steam Station, are a threat to public safety, claiming nearly 50 lives nationwide each year, say civil engineers and dam safety advocates.
Their aim: to educate the public about the hazards of low-head dams and convince dam owners to rehabilitate the structures.
Last week, nine members of an Eden family set out on the Dan River in tubes for a two-hour float that turned deadly when the group went over the Duke Energy dam.
Four survived, and rescue teams have worked for 5 days to recover the bodies of four of five missing tubers, including a 7-year-old boy. The search for Teresa Villano, 35, continued on Tuesday near Draper Landing along the Dan River along N.C. Highway 700.
Low-head dams don’t look dangerous
Survivors say they didn’t realize they were approaching a dam, much less a type of roiling current that is almost always fatal.
And their mistake is a common one, said Andrew Earles, a civil engineer and member of a national coalition of scientists, researchers and outdoors safety advocates who are campaigning for better safety education about the hazards of low-head dams and removal or remediation of the structures.
“When you’re sitting in a raft on a river, you’re down really low to the water’s surface and sometimes you can’t even tell there’s a dam ahead,’’ Earles noted.
But even when tubers and recreational canoeists and kayakers see low-lying dams, they may take deadly risks.
“People underestimate the power of these things,’’ Earles said, explaining that the water at the base of a seemingly innocuous low-head dam features violent reverse current that traps people underwater.
“No. 1, they don’t look hazardous,’’ Earles said of the dams, typically built 5- to 15-feet high. “If these were 100-foot tall dams, no one would think about going over them. But they look like a feature at an amusement park, and a lot of people look at them and think they look like a fun water slide.’’
In reality, the water flowing over low-head dams creates at its base a hydraulic phenomenon known as a reverse roller. A tuber who travels over such a dam can land in what’s known as the “boil zone’’ where current is fierce and moves in a reverse roll pattern. Such rollers trap people and drown them, experts explain.
Low-head dams are often deadly to emergency workers who try to approach a trapped person from downstream, engineers said.
Database shows casualties
While the exact number of low-head dams in North Carolina was not available, a partial registry of fatalities associated with N.C. low-head dams is included in a national database created by researchers at Brigham Young University in Salt Lake City, Utah.
Though incomplete, it shows that since 1960, 11 people have died in seven different incidents after going over the Milburnie Dam on the Neuse River in Raleigh.
The registry also notes one death in Advance, at Idols Dam in 2003, another at a Mocksville dam in 2013, as well as a death at Morganton’s Water Filter Plant dam in 1998.
“My heart sank as I heard the report about the (Eden) drownings, and I knew it had to be a low-head dam even before I knew any details,’’ said Rollin Hotchkiss, creator of the database and professor of civil and environmental engineering at BYU. Link to the database here: htpp://dams.byu.edu.
Earles, who is vice president of water resources with Wright Water Engineers Inc. in Denver, Colo. — a leading firm in low-head dam safety advocacy — and other engineers and scientists have also realized that engineering students graduating from top universities lack knowledge of the risks posed by low-head dams.
“Even engineers with bachelor’s degrees probably aren’t getting instructed about this topic, so how is some kayaker or family on a river going to know?” Earles said, noting safety advocates are promoting more low-head dam curriculum throughout the nation’s engineering schools.
Earles, who has worked on low-head dams from Washington to West Virginia over the past 22 years, grew up paddling the Dan River. The son of a Danville, Va., native, he visited the region often, he said.
Low-head dams have claimed the lives of at least 1,400 people across the nation, according to a data bank compiled by Brigham Young University. In Rockingham County, the 50-year-old low-head dam at Lindsey Bridge in Madison, which claimed the lives of several people in past years, was torn down over the past two years and replaced with an innovative and recreation-friendly weir system.
A low-head dam remains in place along the Mayo River in Mayodan, though outfitters said tubers and paddlers rarely travel the stretch of river it spans.
Thousands of low-head dams were built across the nation beginning in the 1800s to power small industries, such as grist mills and the like. Many remain though they serve no purpose, and some, like Duke’s, are still in use, dam experts say.
Duke’s dam “was designed to provide cooling water for the adjacent power plant starting in 1949. While the coal-fired plant was retired in 2012, intakes by the dam continue to provide cooling water for the Dan River Combined Cycle plant today,’’ Duke’s spokesman Bill Norton said Monday.
In order to remedy the deadly problem low-head dams present, three things must happen: the public must be better educated on risk; signage must be improved near dams; and dam owners, such as utility companies and corporations, must amend low-head dams to feature chutes where boaters and tubers can safely pass, away from the threat of killer current, Earles said.
Such remediation will cost companies, but “one way for them to look at it is: what would the cost of a lawsuit be? … They can compare the liabilities to the cost of fixing it,’’ Earles said. “It is cost-effective to repair these things when you consider the cost of these lost lives.’’
Short of adding a chute to a low-lying dam, owners, communities and state regulators can raise awareness of hazards through education and effective signage, Earles said.
“On a wide river like the Dan you have to be sure they are really prominent … (with commands like) ‘Danger ahead’ and ‘Get out,’’’ Earles said.
Bold, simple warnings and directions and in multiple languages can save lives, Earles said. But to be effective, the signs must be placed upstream, well ahead of dams, so people have enough time to navigate to a bank, get out of water and walk around a dam, a practice known as “portaging,’’ Earles and other river experts said.
Duke Energy, which did have warning signs in place at the time of the Wednesday tubing tragedy, is ready to enhance its signage, Norton said.
“While safety on the river is a broader conversation for the community as a whole, we are installing new, larger warning signs above and below the dam as quickly as possible to reinforce that the public should not approach the dam,’’ Norton said.
Group calls for action
And on Monday the Dan River Basin Association, or DRBA, called for the community to come together to enhance safety and find solutions to eliminate safety risk.
“Anyone who has ever joined an outing with DRBA on a river or trail knows that the safety of our guests is the number one priority,’’ group officials said in a news release.
“DRBA also works closely with municipalities and partners throughout the region to ensure the safety of those enjoying our natural resources by providing paddle and hiking safety training, directional signage on bridges that cross waterways, informational signage along trails and at river access points, and the reconstruction – or deconstruction – of infrastructure that poses potential threats to users. The recent tragic event on the Dan River highlights that there is still work to be done. To that end, DRBA is inviting its municipal, tourism, outfitters and corporate partners to join a renewed conversation about outdoor recreational safety.’’
And Duke wants to participate.
“Like the rest of the Eden and Rockingham community, we are saddened by the tragic event that took place last week on the Dan River. We certainly want to participate in a community discussion on recreation and safety in and around the river,” said Davis Montgomery, Duke Energy’s district manager.