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| Updated: 11/19/09 | |
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The dam and the levees along the Green River have provided effective flood control over the years. However, during the storms this past January, structural weaknesses were discovered. UPDATE: The Corps recently completed interim repairs at the Howard Hanson Dam which reduces the risk of flooding along the Green River Valley from 1 in 3 to 1 in 25. However, the risk is still significant and individuals and businesses should continue their efforts to prepare for and mitigate against the risk of flooding. Read more: USACE completes interim work. The Corps will keep water levels below the maximum pool level until permanent repairs have been completed. If we experience significant rainfall during the upcoming storm season, higher than normal water flows may be released from the dam. This could cause levees below the dam to overtop impacting areas along the Green River. Did you know - As little as one inch of flood water could cost several thousands of dollars to clean up, repair, and replace the contents of your home or business. As the flood season approaches it is critical that individuals, businesses and community organizations prepare for potential flooding. Take action now. |
The Howard Hanson Dam is an earthen dam located near the headwaters of the Green River in King County. The dam was constructed by the U.S. Army Corps of Engineers and went into operation in 1961 for the purpose of flood control for the Green River Valley (1).  |
Prior to Flooding - Prepare and Mitigate Did you know that just one inch of water can cause costly damage to property - possibly even thousands of dollars? Mitigation is the first step toward minimizing the impact of a flood or any type of disaster. Mitigation is defined as the actions taken to eliminate or reduce long term risk to life, property, and the environment from natural and technological hazards (sometimes this may be referred to as prevention).
Protect Your Employees
Protect Your Business/Organization
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During Flooding - Respond Rapid response to a flood can save lives and minimize damage to equipment and property. Ensure all employees and staff know the appropriate actions required to effectively respond to a flood event.
Know the Terms The NWS issues flood and weather outlook, watches, warnings, and advisories in the effort to help protect lives and property.
When Flooding is Possible/Probable
Flood Evacuation Routes
Road Alerts:
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After Flooding - Resume Resumption of 'business as normal', or recovery, includes activities undertaken after an event to return vital economic systems to minimum standards (in the short-term) and all economic systems to normal or improved levels (in the long-term). These activities can include damage assessment, data recovery, debris removal, crisis counseling, public information, reconstruction, or temporary housing.
Record Damage to Your Business or Property
More Resources |
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Prior to Flooding - Prepare and MitigatePreventing flooding around your home
Why you need flood insurance Many people assume they will never need flood insurance because they believe federal disaster assistance will be available. However, flooding does not always receive a federal disaster declaration. Even when it does, aid is usually offered in the form of a loan which must be paid back with interest. Learn more... Myths and facts about flood insurance To clear up some misconceptions about National Flood Insurance, the NFIP has compiled the following list of common myths about the program and the real facts behind them, to give you the full story about this valuable protection. Learn more... Protecting your home from back flow The sewage/septic system is designed to remove sewage from a house. If flood water enters the system, the sewage can backup and enter your home. To help prevent this, install a backflow valve in the sewer line. Learn more... Prepare Your Loved Ones
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During Flooding - Respond The steps you take today can improve your safety and that of your loved ones. This is especially true for a flood event when there may be only a short time to move to a safer place.
If You Must Stay in Place
Personal Safety |
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After Flooding - Clean Up If your house or its understructure have been under water from flooding, you will need to take important steps to begin recovering from the flood and cleaning up your home.
Record Damage to Your Home or Property
Pumping Out Your Basement If you drain your basement too quickly, the pressure outside the walls will be greater than the pressure inside, which may cause the basement floor and the walls to crack and collapse.
Cleaning Up and Drying Out Your Home If your house or its understructure have been under water from flooding, you will need to take important steps to clean out bacteria and mold, and dry the building out thoroughly.
Disinfect all surfaces that were soaked by flood waters with "disinfecting" or "sanitizing" products. An alternative is to use a mixture of 1/4 cup liquid chlorine bleach mixed into one gallon of water. Remove mildew using household mildew removers or fungicides. CAUTION: NEVER mix bleach and ammonia cleaning products. This will produce deadly chlorine gas! |
There are a wide range of steps you can take around your property to reduce the impact of stormwater and even reduce the chances of floodwaters entering your home. 
If your basement is flooded, don’t rush to pump it out. Water in the ground outside your house is pushing against the outside of your basement walls, and the water inside is pushing right back.
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Sources:
1). USACE - Howard Hanson Dam
King County Emergency Management
U.S. Army Corps of Engineer - Howard Hanson Dam
U.S.G.S.
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