What are wetlands?

Wetlands are lands where saturation with water is the dominant factor determining the nature of soil development and the types of plant and animal communities living in the soil and on its surface (Cowardin, December 1979). Wetlands vary widely because of regional and local differences in soils, topography, climate, hydrology, water chemistry, vegetation, and other factors, including human disturbance. Indeed, wetlands are found from the tundra to the tropics and on every continent except Antarctica.

For regulatory purposes under the Clean Water Act, the term wetlands means "those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs and similar areas."

[taken from the EPA Regulations listed at 40 CFR 230.3(t)]

For more information on Wetlands, check out http://www.epa.gov/OWOW/wetlands/facts.html [note: this website link, from the Cambridge City website, returned a page-not-found error message on November 5, 2010], a part of the EPA office of Wetlands, Oceans, and Watersheds web page.

What are floodplains?

Floodplains are any areas of land susceptible to inundation by floodwaters from any source. A 100-year floodplain differs in that it is an area adjoining a river, stream, or other waterway that is covered by water in the event of a 100-year flood. A 100-year flood is a flood having a one- percent chance of being equaled or exceeded in magnitude in any given year. The 100-year floodplain is considered a Wetland Resource Area under the Wetlands Protection Act.

Minimal 100-year floodplain still exists along the Charles River in Cambridge. However, the Alewife district, located in Cambridge, Arlington, and Belmont, consists of several hundred acres of sensitive ecological marshlands located entirely within the 100-year floodplain of the Alewife Brook.