Dam Safety

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Dam Emergencies & Emergency Action Plans (EAPs)

In Nebraska, at least one dam fails almost every year, putting lives at risk and causing damage to downstream property. Even a small dam can release large quantities of water and sediment capable of causing catastrophic damage for miles downstream, destroying crops, roads, highways, bridges, buildings, and homes. Knowing how to recognize problems and the proper actions to take is very important for every dam owner to know in order to minimize the threat to life and property.

 

black and white photo of Destruction downstream of South Fork Dam following its failure in 1889

Destruction downstream of South Fork Dam following its failure in 1889.

 

Signs of a Dam-Related Emergency

  • Water is about to flow over the crest of the dam
  • Erosion in auxiliary spillway that is progressing upstream and is likely to break through into the reservoir
  • Uncontrolled seepage from the dam that is cloudy/muddy or rapidly increasing in flow
  • Boil with cloudy/muddy discharge and increasing in flow
  • Cracks or sinkholes on dam with increasing downstream discharge
  • Sudden rapidly proceeding slides of the dam embankment slopes with seepage emerging from the slide area

For more information see Common Problems at Dams.

 

What to do in an Emergency

  • Notify local law enforcement by calling 911. Be prepared to tell them the location of the dam, the severity and nature of the problem, and the downstream area that may be affected
  • Do whatever is necessary to bring people in immediate danger to safety
  • If time allows, take immediate action to delay, moderate or prevent the failure of the dam
  • Call NeDNR at 402-471-2363 for technical advice

 

Emergency Actions to Save a Dam

Emergency Condition Observed at Dam

Emergency Remedial Actions to Save Dam (call NeDNR at 402-471-2363 for technical advice)

  • Water is about to flow over the crest of the dam
  • Place sandbags along the low areas of the top of the dam to control wave action, reduce the likelihood of flow concentration during minor overtopping, and to safely direct more water through the auxiliary spillway
  • Cover the weak areas of the top of the dam and downstream slope with riprap, sandbags, plastic sheets, or other materials to provide erosion-resistant protection
  • Erosion in auxiliary spillway that is progressing upstream and is likely to break through into the reservoir
  • Place rockfill or sandbags upstream of the eroded area to slow/redirect the flow of water
  • Excavate a long, shallow ditch around the other end of the dam to safely lower the reservoir level
  • Uncontrolled seepage from the dam that is cloudy/muddy and rapidly increasing in flow
  • Boil with cloudy/muddy discharge and increasing in flow
  • Cracks or sinkholes on dam with increasing downstream discharge
  • Open spillway gate and set up pumps or siphons to lower the reservoir level
  • Plug the entrance to the seepage origination point with readily available materials such as hay bales, bentonite, soil, sand, rockfill, or plastic sheeting
  • Cover the seepage exit area(s) with several feet of sand, gravel, and rock to hold fine-grained embankment materials in place
  • Construct sandbag or other types of ring dikes around seepage exit areas to retain a pool of water, providing backpressure and reducing the erosive nature of the seepage
  • Sudden rapidly proceeding slides on the dam embankment slopes with seepage emerging from the slide area
  • Open spillway gate and set up pumps or siphons to lower the reservoir level
  • Repair settlement of the crest by placing sandbags or earth and rockfill materials in the damaged area
  • Stabilize slides by placing a soil or rockfill buttress against the toe of the slide

 

Emergency Action Plan (EAP)

In order to protect life and property, the owner of every high hazard potential dam shall develop and periodically test and update an emergency action plan to be implemented in the event of an emergency involving such dam. The owner of any significant hazard potential dam may also be required to develop and periodically test and update an emergency action plan if determined necessary by the NeDNR. To find out the hazard classification of your existing dam, see the Interactive Map. To learn more on how dams are classified, see the Hazard Classification section of About Dam Safety. For purposes of evaluating the adequacy of an emergency action plan, the NeDNR shall review, evaluate for adequacy, and approve or disapprove each emergency action plan submitted. All non-federal emergency action plans submitted after July 1, 2009, shall be in the same format as the fillable EAP template which can be downloaded below.

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