What is a floodplain?

A floodplain is a wetland that floods following storms or snowmelt. The most commonly found floodplains in Holliston are areas bordering rivers, streams, and ponds (known as Bordering Land Subject to Flooding - or BLSF for short) and isolated depressions that flood annually at least (Isolated Area Subject to Flooding - or ILSF).

Generally, floodplains are defined by the 100-year floodplain. This area is bounded by the estimated maximum flood area that floods on average once every 100 years following a massive storm event.