Functions of Floodplains

Floodplain lands and adjacent waters combine to form a complex, dynamic physical and biological system found nowhere else. When portions of floodplains are preserved in (or restored to) their natural state, they provide many benefits to both human and natural systems.

Floodplain Lands and Waters


The most significant benefit of undeveloped floodplains is that they provide a place for the floods to go! When flood waters are able to spread out over a floodplain, the water velocity is reduced, sediments and debris settle out and less damage occurs downstream. For that reason, as well as the significant public safety benefit and to avoid property damage, development in the floodplain is restricted. You can learn more about this under Permit Requirements.


Floodplains also provide excellent habitats for fish and wildlife by serving as breeding and feeding grounds. They also create and enhance waterfowl habitats, and help to protect habitats for rare and endangered species.

Floodplain Development - Permit Requirements

Placing fill or building in the floodplain (the Special Flood Hazard Area or SFHA) requires permits from both the Conservation Commission and the Planning Board. Such permits include requirements that fill placed in the floodplain be balanced by removing fill from another area of your property. This balancing is known as “compensatory flood storage” and required by both the Wetlands Protection Act and Braintree Zoning Bylaw. Floodwaters displaced by the fill have to go somewhere, so it is up to the person filling to create a place for it to go. Also, the zoning bylaw requires that the lowest floor, including the basement, be elevated at least one foot above the 100 year flood elevation.


Contact staff from Planning and Community Development to discuss your project and application requirements.