| A | B |
|---|
| anadromous | fish that migrate upriver to spawn |
| alewife | kind of herring, an anadromous fish |
| dam | structure built across a river to control water flow |
| estuary | area where fresh and salt water mix |
| gristmill | mill for grinding corn |
| mill | factory powered by water flow |
| current | natural movement of water downstream |
| spawn | return of fish to place of birth to lay eggs |
| landfill | filling in areas of water to create new land |
| mudflat | land covered at high tide, exposed at low tide |
| pilings | used to support buildings in wet soils |
| salt marsh | low coastal grassland covered by sea water at high tide |
| Massachusetts | Native Americans who lived near the Shawmut peninsula |
| Shawmut | name of Boston's original peninsula |
| tides | rise and fall of the ocean level twice daily |
| weir | fence placed in a stream to catch fish |
| locks | parts of a dam that raise or lower water level |
| dredge | digging up a river bottom to make it deeper |
| eel | catadromous fish found in the Charles River |
| catadromous | fish that live in a river and spawn in the ocean |
| fish ladder | dam passageway so fish can swim through |
| watershed | total land area that drains into a body of water |
| canal | man-made channel between two bodies of water |
| basin | area of a river enclosed so that the water level stays the same |
| clams | shellfish common to mudflats |
| heron | long-legged marsh and river bird |
| bass | large fish that feeds on herring |
| downstream | in the same direction as a river moves, closer to its mouth |
| upriver | closer to the source of a river |
| migration | mass movement of animals at a certain time of year |
