History

The Charles River, known as the infamous “Dirty Water” from the Standell song and warmly nicknamed “Chuck” by local rowers, collects from a total land area of 308 square miles. Boston marathoners race 26 miles from Hopkinton to Boston, but the Charles River twists and turns on an 80-mile course between the same points. Because of its meandering nature, the river flows through 23 communities, adding many political complexities to watershed management. Some 80 brooks and streams, and several major aquifers, feed the Charles River. Its watershed contains 33 lakes and ponds—most of them manmade. The river drops about 350 feet in its unhurried journey to the sea. Lacking speed and force, the slow-moving Charles River will always be brownish in color, no matter how clean it becomes. River water steeps like tea through the abundant wetlands along its path.

Watershed

A watershed is an area of land that drains to a river, lake, or ocean. When rainwater hits the ground, mountain and hill ridges channel runoff water and groundwater into water bodies, such as streams and rivers. As water flows over land surfaces it picks up particles, nutrients, and pollution that drain with the water into rivers, lakes, or oceans. Watershed science is therefore an important part of remedying problems, such as pollution, that may affect a particular body of water.

Watersheds do not conform to political boundaries; managing a watershed as a whole achieves better conservation strategies that work with the natural layout of the land. Cooperation increases the ability of organizations to effectively handle watershed problems, which in turn leads to better economic and scientific management of the river and its watershed. CRWA strives to protect the Charles River by promoting this cooperation between diverse organizations, communities, and levels of government.

Everyone has a watershed address. Find out which watershed you live in by visiting the EPA's Surf Your Watershed site.

Charles River watershed towns:

Arlington, Ashland, Bellingham, Belmont, Boston, Brookline, Cambridge, Dedham, Dover, Foxbourgh, Franklin, Holliston, Hopedale, Hopkinton, Lexington, Lincoln, Medfield, Medway, Mendon, Milford, Millis, Natick, Needham, Newton, Norfolk, Sherborn, Somerville, Walpole, Waltham, Watertown, Wayland, Wellesley, Weston, Westwood, Wrentham​

Challenges

climate change

The National Climate Assessment, released in November 2018, offered dire predictions for the Northeast in coming months and years from climate change: increases in total precipitation, especially winter and spring; extreme precipitation events; recurrent flooding; more heat-related deaths; greater evacuated and displaced populations; and all of these impacts are exacerbated by our aging infrastructure including water, sewer, stormwater, and transportation. Locally, since 1958, the amount of precipitation that falls during heavy storms (the largest 1% of storms) has increased by over 70%; this increase is almost double the increases observed elsewhere in the United States. CRWA is working with both traditional and non-traditional partners to take on this challenge. Climate impacts disproportionately impact vulnerable populations, such as the elderly, chronically ill, and low-income residents, not only in the long term but also in the immediate aftermath of severe weather events, as these individuals are less likely to have the means or capacity to move to safer ground, pay for alternative housing, or meet ends without income if they cannot reach their place of work.

stormwater

Runoff from rain and snow is one of the most significant sources of pollution to the Charles River, as it negatively impacts fisheries, habitat, aquatic flora, recreational uses, and aesthetic beauty. Much of CRWA's work in this area is with municipalities focusing on stormwater management, financing, and creation of stormwater by-laws. Studies done in the early 2000s found that nutrient pollution in stormwater runoff to the Charles River is twice as much as it should be in a healthy river system. A recent stormwater permit issued to Charles River cities and towns by the U.S. EPA, known as the MS4 permit, requires municipalities to take steps to reduce this pollution in the coming two decades. Excess nutrient pollution leads to overgrowth of invasive species, algae and cyanobacteria blooms, fish kills, and an abundance of unsightly foam in the river.

cyanobacteria (Blue-green algae)

Cyanobacteria, also called blue-green algae, are microscopic cells that naturally grow in rivers and lakes. Cyanobacteria populations can explode in warm water with excess nutrients, and exposure to these blooms can have negative health effects for humans, animals, and ecosystems. CRWA monitors cyanobacteria levels in the Charles River Basin in Boston and Cambridge during the summer and reports high levels to the Department of Public Health.

water quality

Polluted storm water carrying bacteria, phosphorus, and other pollutants is currently the biggest obstacle for the Charles River. An additional major source of pollution is sewage that enters the river when the sewers overflow after a heavy storm causing elevated levels of bacteria. Elevated bacteria levels can pose health hazards to people who come in direct contact with the water.  Bacteria levels in the Charles vary day-to-day based on recent rainfall and other factors. 

Low stream flow, elevated water temperature, and excessive levels of phosphorus from stormwater combine to contribute to the excessive growth of aquatic plants such as water chestnuts, milfoil, and cyanobacteria.  As the algae and plant matter die and decompose, they deplete the supply of oxygen in the water, causing the death of other organisms, including fish, and damaging the river ecosystem. This process is called eutrophication.

High levels of cyanobacteria (also known as blue-green algae) produce toxins which can be harmful on contact or ingestion.  Warm water temperatures and high levels of phosphorus encourage cyanobacteria to grow excessively.

streamflow

As a highly developed watershed that continues to experience rapid development in the upper and middle sections, landscape alterations and high water demands threaten water levels in the river. Buildings and pavement prevent rainwater from infiltrating into the ground to recharge groundwater and many communities in the upper and middle watershed rely on it for local drinking water supplies. Groundwater is the only source of river flow when it's not raining, providing water for rivers and streams, but less and less of it is reaching waterbodies. Fish and other aquatic life require adequate water levels for a health habitat during dry conditions and human impacts, especially in the summertime, can cause smaller streams to dry up or become very shallow and hot, seriously degrading natural habitat.

dams

There are currently dozens of dams across the watershed, the vast majority of which were constructed for a purpose they are no longer serving, such as hydropower, or even in some cases, flood control. Dams degrade natural river habitat and in the age of climate change they can also pose a significant threat to downstream areas, as our existing dams were designed for historic rainfall conditions and not those expected from climate change. ​