Green River & Howard Hanson Dam Emergency Information
Background
Flood Basics
Terms You Should Know
Who and What Could be Affected?
What Renton is Doing to Prepare
Getting The Word Out
Preparing Citizens and Businesses
Steps Business Owners Should Take
Steps Residents Should Take
Frequently Asked Questions
Background
The U.S. Army Corps of Engineers (USACE) manages the Howard Hanson Dam near the headwaters of the Green River. The dam helps maintain water storage and reduces the risk of flooding in the Green River Valley/floodplain. After this winter’s storms, USACE discovered accelerated leakage through the right abutment of the dam.
As a result of this finding, USACE has determined the dam will be unable to hold as much water during heavy rains. This situation creates a higher possibility of flooding in areas of Renton located in the floodplain (Highway 167 west to the Green River and Renton’s southern boundary north to the Burlington Northern railway corridor). To see City of Renton maps of potential flooding scenarios,
click here
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The U.S Army Corps of Engineers recently made flood scenario maps available for the entire Green River Valley. The maps show four potential scenarios. To see Green River Valley maps,
click here.
Although it would take a catastrophic event for the floodwaters to reach downtown Renton and significant flooding may not occur, there is a heightened risk of flooding within the Green River floodplain and areas surrounding the floodplain due to the condition of the dam.
The Army Corps of Engineers has made an interim fix to address the problem but won’t be able to test it until next summer when the risk of flooding is lower. They continue to work to find a solution to the structural issues affecting the dam, but a permanent repair may take 3 to 5 years to complete. In the meantime, the lower Green River Valley will be threatened by seasonal flooding not seen in fifty years.
Flood Basics
Floods are one of the most common hazards in the United States and can be caused by weather conditions such as heavy rainfall associated with severe storms, melting snow and ice. Flood effects can be local, impacting a small area, neighborhood, entire community or regional. Floods can occur anywhere under the right conditions and are highly unpredictable.
The National Weather Service does monitor incoming storms and weather conditions in an effort to provide some warning if flooding is probable. What is difficult to estimate is the amount of water that could be seen and the direction it might take, so everyone needs to take a reasonable approach to the risk and prepare now.
Terms You Should Know
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Flood Warning – flooding is occurring or will occur soon. If advised to evacuate, do so immediately.
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Flood Watch – Flooding is possible. Stay tuned to NOAA radio, commercial radio or television for additional information.
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Advisory – A weather condition that is less serious than a warning. This event may cause significant inconvenience, and if caution is not exercised, it could lead to a situation that may threaten life and/or property.
Who and What Could be Affected?
Businesses occupy the majority of the area in Renton affected by the Green River. (Highway 167 west to the Green River and Renton’s southern boundary north to the Burlington Northern railway corridor). Although there is potential for deep water in some areas under the direst of flood scenarios, lower levels of flooding are much more likely.
As a result of flooding transportation routes will be affected; those who travel through the floodplain could experience delays, road closures/detours and possible reductions in public transportation. Water may enter some buildings, and operation of King County’s wastewater treatment plant (located in Renton) may be impacted. As with other storm and weather related emergencies, the region could experience utility outages.
What Renton is Doing to Prepare
The City of Renton has been monitoring the potential flooding situation since the concern was raised earlier this year. In collaboration with neighboring cities, Renton is developing a comprehensive strategy to deal with potential flooding in the valley with a focus on preventing injuries and minimizing potential damage, especially to the business community. The city continues to do all it can to keep citizens informed about the issue with frequent press releases and web site updates.
A pre-incident state of emergency was proclaimed by the Mayor as a proactive measure in facing the elevated risk of flooding on the Green River. The proclamation provides city departments with the required authorization to prepare for, stabilize and control any emergency or disaster situation.
The city has applied for “advance measures funding” from the USACE, to receive assistance to prepare for flooding. If approved, the city would purchase flood barriers that will be installed prior to flood season.
Renton is also coordinating with King County to obtain large diesel powered pumps. These pumps would be temporarily installed at the Black River Pump Station to try to keep water levels in Springbrook Creek below flood stage. The other jurisdictions that have levees on the Green River levees are also planning similar flood mitigation measures. We are also working with Tukwila and Kent to raise the elevation of the Green River levees so that they will contain a higher flow before flooding. The work will be done sometime during the month of October, 2009.
Other efforts the city is doing in preparation for potential flooding is to continue its work with the Army Corp of Engineers, King County and neighboring cities to implement coordinated pre-flood advance measures, placing emergency electrical generators in strategic locations for use during possible power outages which will run all well pumps and booster pump stations.
Renton is taking steps to protect public facilities using sandbags and if deemed necessary will identify a sandbagging facility for members of the public to obtain sandbags. In continued anticipation we are also identifying a staging area for debris removal should that become necessary.
Getting the Word Out!
Local, state, and federal agencies strive to keep the public informed of emergencies and advise them of what protective actions they should take during an emergency situation. The City of Renton has a variety of warning systems in place to alert the community in an emergency incident. It is important to know how they work and where to look and listen to protect yourself and your family, your home and business.
Depending on the type of emergency incident that occurs, trained emergency personnel will quickly choose the most appropriate and effective way to issue an immediate and urgent warning to the public. The following warning methods might be used in an emergency:
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- CodeRed™ Emergency Community Notification System, often referred to as "reverse 9-1-1"
- Emergency Alert System (EAS) warning sent out to all broadcasters to relay to the public
- NOAA Weather Radio, which will also alert to an EAS activation
- Private notification services, which may also relay EAS alerts
- Electronic road sign activation
- Emergency news release posted by the City or other agencies to www.rpin.org
- The Critical Emergency Information page at rentonwa.gov
Preparing Citizens and Businesses
The Renton Emergency Preparedness Academy (REPA) is a partnership between the City of Renton, the American Red Cross, and Renton Technical College. REPA offers a number of classes to help people prepare for any kind of disaster. Most classes are free. The complete list of classes can be found in the latest edition of the “What’s Happening” or at rentonwa.gov. Register for the REPA courses through the Renton Community Center.
The city has been responding to calls from residents and working directly with businesses to provide information and resources to assist them in putting together their own flood response plans to protect their facilities and inventory in case of a flood.
Renton continues to work with other cities to address the regional impacts of possible flooding. The city has partnered in several public meetings designed to inform the public about this possible situation and to encourage them to prepare now. Regionally, effort is also being made to identify which roads or highways to use in case of an evacuation. Everyone should become familiar with the defined evacuation routes and monitor the status of roads and transportation regularly during a flooding incident.
Steps Business Owners Should Take
Taking steps to prepare now can make a significant difference in how a business weathers the storm. Renton businesses in the floodplain should make sure they have flood insurance and should develop an emergency plan for each facility that includes measures to protect facilities, personnel and inventory. Other considerations to include in your plan are: a way to reunite with coworkers/family members, business continuity, sewage damage insurance rider, and basic supplies.
Business owners may want to relocate critical items to high ground, or if items must remain in the building store them as high as possible. Consultation with a structural engineering firm is recommended to determine the best flood protection measures to use for your building.
Business should also sign up for CodeRED, the city’s emergency notification system. Additionally, all businesses, regardless of their flood risk, should have a business continuity plan to guide their operations should a business interruption occur. Renton businesses can contact the Office of Emergency Management at 425-430-7000 or by email at dneedham@rentonwa.gov, for assistance with planning and preparedness.
Steps Residents Should Take
Ways You Can Help
If flooding occurs there will be many ways to lend a hand. If you are willing to help, please register today with Volunteer Solutions. The City of Renton and other agencies will be requesting volunteers if needed using this website.