Flood Preparedness

There are many factors that can lead to flooding, and also variable levels of what is considered “flooding.” Whether neighborhoods experience consistent water backups on streets and sidewalks following rainstorms, or water rises in excess of several feet in low-lying areas, these are issues we are actively working to address at the municipal level.

In the short term, we can work to control or mitigate minor flooding through typical city services like regularly scheduled street sweeping, clearing catch basins, and properly maintaining sewers.  In the longer term, we are making significant investments in and upgrades to our aging infrastructure. Projects across the city like the Somerville Ave. Utility and Streetscape Improvements Project, the Marginal Interceptor Rehabilitation Project, and ongoing sewer inspection and rehabilitation projects will not only upgrade our combined sewer system, but also greatly enhance capacity for stormwater management.  

Finally, and perhaps the most critical factor impacting flooding, is the fact that climate change is causing Somerville to experience more frequent and intense rainstorms, which leads to more flooding, including in places that typically do not experience flooding. The City of Somerville, partner agencies, and community advocates are actively working to address and prepare for climate change in a number of ways. In late 2018, we released Somerville Climate Forward, our first comprehensive climate change action plan, with implementable actions to reduce Somerville’s contribution to climate change. You can view the full plan at somervillema.gov/ClimateForward.

The City of Somerville is actively planning for the effects of climate change and making improvements to our aging infrastructure, but it is also important that residents, business owners, and developers take the necessary steps to prepare your properties in advance of potential flooding. Learn more here about what is happening in Somerville, whether your home or business is at risk, and how to respond before, during, and after a flooding event.

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  • Background

  • Frequently Asked Questions

There are many factors that can lead to flooding, and also variable levels of what is considered “flooding.” Whether neighborhoods experience consistent water backups on streets and sidewalks following rainstorms, or water rises in excess of several feet in low-lying areas, these are issues we are actively working to address at the municipal level.

In the short term, we can work to control or mitigate minor flooding through typical city services like regularly scheduled street sweeping, clearing catch basins, and properly maintaining sewers.  In the longer term, we are making significant investments in and upgrades to our aging infrastructure. Projects across the city like the Somerville Ave. Utility and Streetscape Improvements Project, the Marginal Interceptor Rehabilitation Project, and ongoing sewer inspection and rehabilitation projects will not only upgrade our combined sewer system, but also greatly enhance capacity for stormwater management.  

Finally, and perhaps the most critical factor impacting flooding, is the fact that climate change is causing Somerville to experience more frequent and intense rainstorms, which leads to more flooding, including in places that typically do not experience flooding. The City of Somerville, partner agencies, and community advocates are actively working to address and prepare for climate change in a number of ways. In late 2018, we released Somerville Climate Forward, our first comprehensive climate change action plan, with implementable actions to reduce Somerville’s contribution to climate change. You can view the full plan at somervillema.gov/ClimateForward.

The City of Somerville is actively planning for the effects of climate change and making improvements to our aging infrastructure, but it is also important that residents, business owners, and developers take the necessary steps to prepare your properties in advance of potential flooding. Learn more here about what is happening in Somerville, whether your home or business is at risk, and how to respond before, during, and after a flooding event.

The City is using a wide range of strategies to address flooding, including maintaining our stormwater management system, increasing community outreach and preparedness, implementing flood mitigation solutions, and focusing on climate action. More information, including the work of specific departments, can be found in the other sections of this page.

Yes, climate change means that flooding will happen more often and more intensely, including in places that haven‘t typically flooded in the past. This increase in flooding will happen for two different reasons. First, there will be more frequent and intense rainstorms, with a predicted 30% increase in rainfall during a 100-year, 24-hour event by 2070 (Somerville Climate Vulnerability Assessment, 2017). A 100-year storm has a 1% chance of occurring in a given year. Second, Somerville will experience sea level rise and storm surge-related flooding from the Mystic River, as sea levels in Boston Harbor are predicted to rise 4 to 8 inches by 2030 and 15 to 36 inches by 2070. For more information, please see Somerville’s Climate Change Vulnerability Assessment.

By visiting the “Flooding Maps and Information” tab on this website, you can explore flooding projections for the City of Somerville for three different types of storms: a frequent, current-day storm; a moderate storm in 2030; and an extreme storm in 2070. These maps will help you to identify if your property is in an area that is more vulnerable to flooding (and at what depth), but they do not indicate every possibility of future flooding. There is uncertainty in the models, so some areas might experience more flooding than projected and other areas might experience less, depending on storm conditions and other variables.

If you need assistance or have questions, please call 311 for immediate response, as long as the issue is not an emergency (i.e., it does not pose an immediate danger to you or others). If you are caught in a flood and require emergency assistance, always call 911. Lastly, you can share flooding photos and updates with the City at [email protected] to inform future flood reduction efforts.

Call 311 to request City assistance in cleaning out catch basins.

  • Make sure Wireless Emergency Alerts for emergency and public safety are enabled on your phone. The Massachusetts Emergency Management Agency (MEMA) has information on their website about the Emergency Alert System and Wireless Emergency Alerts.
  • You can also follow MEMA on Facebook and Twitter for weather and other emergency information.
  • You can enter your zip code on the National Weather Service website to see any current weather advisories or alerts.
  • Many weather apps offer extreme weather alerts. Check the settings on the one you use to see if that’s an option.
  • Some home security companies and sump pump manufacturers offer services that will send you an alert if moisture is detected in your basement.