Much of the river's lower section, as it winds past Harvard University and downtown Boston, is gracefully landscaped and lined with boathouses and recreational paths. The tradition of boating on the Charles now includes rowing shells, sailboats, powerboats, windsurfers, kayaks, canoes, solar-powered crafts, rafts, even inner tubes. The river's 80 miles of flow winds through 20 miles of landscape that is primarily urban. Although water quality in the Charles has been steadily improving, several continuing problems have a huge impact on water quality, especially in wet periods. A crush of growth in the upper reaches of the watershed has increased the amount of paved and impervious surfaces.
Heavy rains wash contaminants into the river from sewer overflows and stormwater runoff.
Contamination of the Charles comes from both point source and nonpoint source pollution. Point sources include illegal sewer connections to storm drain systems. Nonpoint sources include polluted runoff from stormwater. The growing demand for water in many parts of the watershed depletes sources of drinking water during low-flow conditions. Fecal coliform bacteria.