CHARLES RIVER MATCH Play these games to learn or review vocabulary about rivers and how people have interacted with them over time. Tools 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