What is a Dam Failure?
Dams can fail for a number of reasons, including overtopping caused by floods or structural failure of materials used in dam construction. On Oahu, during heavy or prolonged periods of rain, dams and reservoirs may fill up and approach their capacity, posing an increased risk of failure. Dam failures may occur quickly and without much warning, causing severe flash flooding in the surrounding area and resulting in extensive property damage and loss of life.
What is a dam? A dam is a barrier constructed to hold back water, resulting in a pool that can be used for a variety of purposes; agriculture, water supply, electricity generation, flood or sediment mitigation. There are 13 regulated dams on Oahu, primarily in Central Oahu, originally built for irrigation storage. Most were built prior to modern construction standards, making them vulnerable to dam failures.
The Hawaii Department of Land and Natural Resources (DLNR) Engineering Division administers the Hawaii Dam and Reservoir Safety Program to protect the health, safety, and welfare of the citizens of the State by reducing the risk of failure of the dams or reservoirs.
Dam failure can happen in a number of ways. Learn more about each one by hovering over the boxes below:
Structural Failure
Structural Failure
Mechanical Failure
Mechanical Failure
Hydraulic Failure
Hydraulic Failure
If I need to evacuate, how will I be notified? If evacuations are ordered, emergency officials will broadcast alerts to radio, TV, mobile devices, social media, and HNL Info. As much as possible, emergency responders will drive through neighborhoods and issue evacuation orders over loudspeakers.
Am I at risk where I live?
If you live downstream of a dam, then you potentially live in a dam evacuation zone. Downstream could mean any number of miles from the dam or reservoir itself. For more information on a specific dam, visit the City Dam Evacuation Planning Tool for Oahu www.honolulu.gov/damevac. Click on the name of the dam to view detailed data on the dam type, owner and hazard potential, view photos and download evacuation maps.
How do I stay safe?
Actions to Take TODAY
Dam failures can happen with very little notice. If you live in a dam evacuation zone, make sure you take steps to be prepared in case of an evacuation notice.
Every family is unique and so is every family’s emergency plan. Think about what special people, pets, or circumstances you should plan for. Do you have keiki or kupuna who might need extra help in an emergency? Do you have a pet that you need to pack food or a crate for? What about your power requirements? Do you need electricity for medical devices? Identify the needs and make a plan for each member of the family ahead of time so you can be confident you can take care of your family in an emergency.
Every emergency plan should include some essential things:
- Know if you will have to evacuate your home.
- A location where your family plans to meet if you need to evacuate or are separated.
- Contact information for family members, friends, workplaces, medical providers, and other important contacts. Establish an off-island or out-of-state contact that everyone in your family knows to contact in the event on-island communications are limited.
Learn more at honolulu.gov/dem/preparedness/make-plan.
Identify the route you would take to leave the evacuation zone. If possible, identify a back up route in case of traffic or other impediments to your primary route.
Some disasters or emergencies like tsunamis require quick evacuation. This can occur with little warning, and there may not be enough time to take your entire family disaster supply kit with you.
A Go Bag should provide enough quick-access supplies to get you through the initial phases of an emergency and evacuation. You should have one bag for each member of your household.
Find out what to include in your Evacuation Go Bag at honolulu.gov/dem/build-a-kit.
Purchase flood insurance, as just a few inches of flooding in a home can cause thousands of dollars in damage. Generally, homeowners insurance does not cover flooding.
When a Dam Failure is a Threat
During a dam failure emergency, following official emergency instructions is key. Do not hesitate to take action.
If there is a threat of a dam failure, take these steps to be ready in case you need to evacuate.
- Monitor local radio and TV stations for emergency information and important updates.
- Review your family emergency plan with all members of your household.
- Check the contents of your evacuation go bag.
- Prepare to evacuate in case you need to.
- Have mobile cell phones charged and have an external charger for each
A dam failure fast-moving and life-threatening disaster. If you are ordered to evacuate, do so immediately.
Locations of evacuation centers will be provided to community leaders and the media to share with the public. Stay tuned to local news media and social media channels for up-to-the-minute information. Residents will need to bring everything they might need for at least 3 days – food, water, bedding, pet supplies, toiletries, medications, etc. Evacuation shelters will provide a safe place to stay, but may have limited supplies.
- Monitor local radio and TV stations for emergency information and important updates.
- Call 911 immediately if there is an emergency.
- Move to higher floors if trapped in a building. Go on the roof if necessary. Once there, signal for help.
- Be aware of the risk of electrocution. Do not touch equipment if it is wet or you are standing in water. If it safe, turn off the electricity to prevent shocks.
- Turn around, don’t drown! Do not attempt to walk, swim, or drive through flowing or rising water.
- Floodwaters can rise rapidly and sweep away a vehicle and its occupants. If your vehicle stalls in a flooded area, get out as soon as possible. However, stay inside your car if you are trapped in rapidly moving water. If water is rising inside the car, get on the roof.
After a Dam Failure
After a dam failure, make sure you are staying safe while you assess damage or begin clean up efforts.
Continuously monitor TV (if working) and radio for instructions. Authorities will announce when it is safe to go outside and/or to return to your home.
Be aware of hazards, i.e. down power lines, broken gas lines, contaminated water, weakened structures, broken glass, etc. Debris on roadways will limit your ability to drive around.
When assessing damage, take photos to document your losses.
Once it is safe to return and you have photographed damage, begin cleaning immediately to avoid further hazards like mold growth.