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About the Great Marsh (6/00)

The “Great Marsh” extends from Cape Ann into New Hampshire and covers over 17,000-acres.

Salt marshes are found in coastal areas.These unique ecosystems are formed within protective estuaries and support numerous plants and animals.


Plant Species Present
(Zone: Plants)

A: Common Ragweed, Seaside Goldenrod

B: Salt Hay Grass, Black Grass, Spike Grass

C: Smooth Cord Grass

D: Bullrush, Hightide Bush, Silverweed

E: Smooth Cord Grass, Water Hump

F: Eel Grass

Salt marshes are among the most productive lands on earth, outcompeting even the best-managed farms. Two-thirds of all marine fish and shellfish depend on salt marshes during some portion of their lives.

Salt marshes are divided into two general vegetation zones. The Low Marsh is flooded twice daily by the incoming tide and is dominated by Spartina alterniflora. The High Marsh is flooded sporadically and is dominated bySpartina patens (high salt marsh grass). Salt marshes contain tidal creeks, pools and “islands” of high ground, and serve as highly efficient pollution filters.

Nationwide, vast areas of salt marsh have been destroyed by filling, dedging and developing upland areas. The “Great Marsh” has escaped much of this destruction, but is impacted by pollution runoff and mosquito control ditches built in the 1930s and by road and rail crossings which restrict tidal flows to upstream marshes.