Flood Zones: Somerville vs Waltham
How do flood zones rules compare between Somerville, MA and Waltham, MA?
Somerville and Waltham have similar restriction levels.
Somerville, MA
Middlesex County
Parts of Somerville near the Mystic River and Alewife Brook are FEMA Zone AE. New construction in the floodplain must elevate 2 feet above BFE.
View full Somerville rules →Waltham, MA
Middlesex County
Waltham enforces FEMA floodplain regulations along the Charles River and its tributaries, requiring flood elevation certificates and floodproofing for development in A and AE zones.
View full Waltham rules →Key Facts Comparison
| Fact | Somerville | Waltham |
|---|---|---|
| Zones present | AE and X-shaded | - |
| Freeboard | 2 feet above BFE | 1 foot above BFE |
| Substantial improvement | 50 percent rule | - |
| Insurance | Required in SFHA with mortgage | - |
| Key areas | Mystic River, Alewife Brook, Assembly | - |
| Main Floodplain | - | Charles River Zone AE |
| Substantial Improvement | - | 50 percent market value |
| Floodway Fill | - | Prohibited |
| FIRM Update | - | 2021 effective maps |
Highlighted rows indicate differences between cities.
Somerville FAQ
How do I find out if my Somerville property is in a flood zone?
Enter your address at the FEMA Map Service Center (msc.fema.gov) to pull the FIRM panel and Base Flood Elevation, or call Somerville Planning for a letter.
Can I finish my basement in a flood zone?
Enclosed space below BFE must be used only for parking, access, or storage and needs flood vents. Habitable finishes below BFE are prohibited for substantial improvements.
Waltham FAQ
How do I know if my Waltham property is in a flood zone?
Check the FEMA Flood Map Service Center online by address, or contact the Waltham Conservation Commission for assistance reading the FIRM.
Do I need flood insurance in Waltham?
Federal law requires it for mortgaged properties in Zone AE. Even outside mapped zones, flood insurance is recommended near the Charles River or its tributaries.
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