TIDAL FLOODING happens only on well known dates. Being aware of high tide dates, and your specific vulnerability to tidal flooding, is key to being prepared.  Local tidal information can be found here. Tides over 6’ can cause problems in Mill Valley - especially if combined with winter storm rainfall.


Flooding caused by SEVERE WINTER STORMS – very heavy runoff and flash flooding – occurs when the ground becomes saturated during periods of extreme rainfall, often over many days.  By planning ahead individuals can evacuate (if needed) quickly, calmly and safely, or act in advance to protect their personal property, important documents or family mementos. 


Pre-Planning for Flooding Events


When a flooding event (or any other disaster) occurs, your chances of survival or minimizing the impact of the event on your life depend heavily on your preparedness BEFORE THE EVENT.



•Understand your risk.  Know if your home is in a TIDAL flood zone, is at risk for FLASH flooding from creek overflow, or BOTH. 


•Understand the public information and warning systems.  Heed Mill Valley public safety signs.  Understand TV and Radio weather warnings.  Pay attention to published tide charts.


•Organize your neighborhood.  Share knowledge.  Plan together.  Help each other.


• Review your Family Disaster Plan yearly with all members of your family.  This plan should be simple, written, and include a copy of the FLOOD ACTION CHECKLIST (see Tools below)


BEFORE


Depending on the nature and location of the anticipated flooding emergency, there may be a sufficient amount of time for Public Safety to alert residents of the need to implement immediate flood protection steps.  However, this may not always be the case, such as an event involving flash flooding due to unexpected extremely intense rainfall events.  Advance planning and preparation is always important, and knowing (and respecting) when the risks are high is your responsibility.  


In advance of a potential flood when either high tides or severe rainfall is forecast, signs will be posted around Mill Valley’ flood prone areas to provide public notice of the increased flood risks.  (See Warnings and Alerts) These warnings mean that now is the time for you to act to protect your family and property.  Neighborhood organizations are encouraged to develop phone trees and other communication processes to reach out to each other for notice and help. National weather service radio and TV issued Flood Watches or Flood Warnings for Marin County should be taken very seriously.


DURING


If a flash flooding event occurs, such as a creek overflow due to severe rainfall, the Marin Emergency Advance Notification System (MEANS) will call all residents who have opted into the system with warnings and instructions.  Other methods of alerting residents, including police and fire vehicle loudspeaker announcements, etc. will also be attempted, though it is important to understand that Public Safety vehicles will not enter flooded areas if deemed too dangerous for the police and fire workers.


If a flooding event occurs it is most likely that you will be instructed to shelter in place (that is, stay where you are!)  The Mill Valley Emergency Sirens will NOT be activated for a flooding event.  You should evacuate only if told to do so, and in no case should you (or your children) play in or even walk in moving floodwaters.  Even still floodwaters may pose hidden dangers, such as open storm drain covers, etc.

 

Many parts of Mill Valley are in a flood zone.  Other areas are at risk for overflowing creeks caused by high rains and flash flooding.  As a result, severe winter storms and high tides, alone or combined, have historically caused damaging floods in Mill Valley. 


Remember, the “marsh” alongside Arroyo Corte Madera del Presidio Creek - now the Locust / Lower Sycamore area - used to be navigable up to today’s Montford Avenue, and Richardson Bay itself was navigable up to the High School!


Knowing in advance what you should do before and during a flood event can mean the difference between surviving a flood, or experiencing financial loss or even death.


Your goal should be to be prepared with a plan well in advance of a flooding event and to implement your plan early when the risk of flooding is high.