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Low-head dams: High-risk “drowning machines”

Low-head dams, named for their low profiles, are usually no more than 15 feet tall. While these brick or concrete structures may be small in stature, they often act as “drowning machines,” presenting high risk to anyone entering the waters around the dam.

Upstream of one these dams, the water often looks smooth and inviting. Downstream there are usually excellent opportunities for fishing due to the barrier to upstream migration. The dam itself may not even look threatening. But these dams, which are present in roughly 3,000 locations throughout the U.S. and approximately 50 in North Dakota, have claimed the lives of over 300 people since 1960.

What makes them so dangerous?  Low-head dams are known for creating a circulating roller on the downstream side that can be nearly impossible to escape.

While most low-head dams were created to perform a valuable function at one point, whether for power mills, farm irrigation, impounding drinking water, or to foster recreation, many no longer serve a purpose. In addition to the potential safety issues, many of the dams are in disrepair and present risks due to potential structural failures. If that’s the case, why do so many low-head dams still exist?

Removal of dams is expensive – an effort that can carry a seven-figure price tag, and funding for these projects is a major obstacle for many owners. Ownership itself is also an issue. Many North Dakota dams go unmaintained because no government agency or private party is aware that they own it. Even when ownership is accepted and funds are available, the competing interests involved with these structures – historical preservationists, fishermen or other concerned parties – make it difficult for owners to develop enough support to remove or modify the dams.

So, the death count caused by these “perfect drowning machines” continues to rise, usually when boats capsize and their former occupants face an impossible swimming situation where even a life jacket performs more like a wet towel.

The good news is recent developments may bring change in North Dakota. This year, the North Dakota State Water Commission approved a new cost-share policy that will provide up to 75 percent of the cost of eligible items for dam safety repair projects and dam breach or removal projects. The intent of these projects is to return the dams to a state of being safe from the condition of failure, damage, error, accidents, harm or other non-desirable events. The State Water Commission may lend a portion of the local share based on demonstrated financial need. In addition to these cost-share dollars, there may be other agencies with funding programs that help contribute towards qualifying projects on these dams.

In addition to the funds for addressing the structural needs of these dams, the State of North Dakota is also providing assistance to owners when it comes to planning and preparing for emergencies. A bill was signed in March 2015 affecting owners of medium or high hazard dams in North Dakota. House Bill 1097 added a new section to the North Dakota Century Code in Chapter 61-03 stating that owners of high- or medium-hazard dams need to develop, test and update an emergency action plan (EAP) for submittal to the state engineer.

To aid in the development of these EAPs, the North Dakota State Water Commission may fund up to 80 percent of the cost involved in developing EAPs for high- or medium-hazard classified dams. While developing an EAP was just a suggested guideline just five years ago, dam owners are now required to create one.

With partners like the North Dakota State Water Commission chipping in, it’s a great time for dam owners to consider removing or repairing the dam, if its usable life is expired. At the very least, cities, counties or boards should be knowledgeable about whether they own a dam and have responsibilities they need to meet. Moore Engineering can help you identify if you’re a low-head dam owner.

Moore Engineering assembles studies and EAPs, and has developed numerous dam improvement projects, including current projects in Valley City and Kathryn. We can also help with the determination of dam ownership, offer and explain options and assist with funding sources. For more information, call me at 701-499-5867 or contact us online.

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