USA HISTORY

Detailed explanation-1: -The Charles River is fed by approximately 80 streams and several major aquifers as it flows 80 miles (129 km), starting at Teresa Road just north of Echo Lake (42.215°N 71.514444°W) in Hopkinton, passing through 23 cities and towns in eastern Massachusetts before emptying into Boston Harbor.

Detailed explanation-2: -The Charles River flows 80 miles from Hopkinton, Mass. to Boston Harbor. The Charles River is the most prominent urban river in New England.

Detailed explanation-3: -From the Lower Mystic Lake, the Mystic River flows through Arlington, Somerville, Medford, Everett, Chelsea, Charlestown, and East Boston before emptying into Boston Harbor.

Detailed explanation-4: -The Mystic River forms a partial border between the cities of Boston (the Charlestown area), Chelsea, Medford, Everett, and Somerville. The section of the river upstream of the Amelia Earhart Dam, in the Medford/Somerville area, is used extensively by recreational boaters.

Detailed explanation-5: -The largest rivers draining into Boston Harbor are the Charles, Neponset, and Mystic. Since 1989, MWRA has regularly monitored water quality in these rivers, measuring bacteria, algae, water clarity, dissolved oxygen, nutrients, and suspended solids.