A GIS Analysis of Boston Harbor and the Charles

RiverBoston, MassachusettsAmy Townsend-Small

GIS in Water ResourcesFall 2001

The Boston skyline as seen from the Charles River

Historical Background

The Boston Tea Party may have been the first recorded incident of the pollution of Boston Harbor, but unfortunately it wasn’t the last.

The City of Boston dumped sewage sludge and treated sewage into the harbor for over 100 years.

In the 1988 presidential election, the Democratic candidate, Michael Dukakis, then governor of Massachusetts, was criticized for what Republican candidate George Bush called “the dirtiest harbor in the world”.

President Bush’s comments led to the creation of several state agencies to clean up Boston’s waterways. I’ll be presenting the results of those clean-up efforts.

Artist’s rendition of the Boston Tea Party, 1773

Monitoring the Pollution of the Waters of Boston

HarborIn 1998, sewage discharge was stopped at the Nut Island STP and its sewage was pipelined to the Deer Island STP, where it was discharged into the harbor.

The Massachusetts Water Resources Authority collected the following data before and after the transfer:•Nitrogen concentration•Phosphorus concentration•Chlorophyll-a concentration•Dissolved oxygen saturation•Fecal coliform bacteria counts•Water clarity

InnerBoston HarborCharles River

Deer Island Wastewater Treatment Facility

Deer Island Effluent Discharge Site

Nut Island Wastewater Treatment Facility

Former Nut Island Effluent Discharge Site

Boston

Cambridge

An excess of nutrients like nitrogen and phosphorus can lead to eutrophication of aquatic systems, characterized by microalgae blooms and high dissolved oxygen

saturation.

Dissolved Inorganic Nitrogen in Boston

Harbor

Concentrations of DIN decrease after the transfer of sewage effluent to the new site

Before After

Total Nitrogen in Boston Harbor

Concentrations of total nitrogen decrease after the transfer of sewage effluent to the new site

Before After

Dissolved Inorganic Phosphorus in Boston

Harbor

Concentrations of DIP increase after the transfer of sewage effluent to the new site

Before After

Total Phosphorus in Boston Harbor

Concentrations of total phosphorus increase after the transfer of sewage effluent to the new site

Before After

Chlorophyll-a in Boston Harbor

Standing stocks of chlorophyll-a increased after the transfer of sewage effluent to the new site

Before After

Dissolved Oxygen in Boston Harbor

Dissolved oxygen decreased in saturation after the transfer of sewage effluent to the new site

Before After

Fecal Coliform in Boston Harbor

Fecal coliform counts decreased after the transfer of sewage effluent to the new site

Before After

Water Clarity in Boston Harbor

Water clarity improved after the transfer of sewage effluent to the new site

Before After

Summary of Water Quality Changes in Boston Harbor

Phosphorus and chlorophyll-a increased in concentration

Nitrogen, dissolved oxygen, and fecal coliform decreased in concentration, and water clarity increased.

Whale watchers in Boston Harbor

Heavy Metal Contamination in the Sediments of Boston

HarborIn addition to dumping

sewage effluent, Boston also disposed of sewage sludge into

the harbor for over 100 years. In 1991,

this practice was stopped altogether.

Sewage sludge is high in heavy metals such as iron, copper, and

lead.

How has the concentration of these metals in sediments changed since 1991?

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Deer IslandEffluent Discharge Site

FormerNut Island

Sludge Discharge Site

SedimentSampling Site #1

SedimentSampling Site #2

Lead in Boston Harbor Sediments

Generally, lead concentrations decreased in the former sludge dumping site and increased in the site closer to shore.

1991 1998

Copper in Boston Harbor Sediments

Copper concentrations in the sediments decreased in the former sludge dumping site, and copper concentrations increased in the site closer to shore.

1991 1998

Iron in Boston Harbor Sediments

Again, iron concentrations decreased in the former sludge dumping site and increased in the site closer to shore.

Summary of Changes in Metal Content of Harbor

SedimentsSince the metal content decreased in the former sludge dumping

site, the cessation of sludge has improved harbor conditions. However, there seems to be another source of metals to Boston

Harbor.

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!

Deer IslandEffluent Discharge Site

FormerNut Island

Sludge Discharge Site

SedimentSampling Site #1

SedimentSampling Site #2

Logan Airport

Charles River

Pollution of the Charles River

The Charles River is the largest river that discharges to Boston Harbor. It is also an important recreational

resource for the city. However, it is dangerous to

swim in because of high bacteria levels.

In 1995, the EPA declared its goal to make the Charles

swimmable by 2005. Their efforts have included picking

up trash, the creation of sewage treatment plants in towns along the river that

relied on aging septic systems, and sustainable

development of communities in the watershed

How has water quality changed in the Charles

River?

Boston

Cambridge

Boston Harbor

Total Phosphorus in the Charles River

There is a slight increase in total phosphorus levels in the Charles River between 1997 and 2000.

1997 2000

Total Nitrogen in the Charles River

There was a general decrease in nitrogen in the Charles River from 1997 to 2000

1997 2000

Chlorophyll-a in the Charles River

There was a marked decrease in chlorophyll-a concentrations from 1997 to 2000

1997 2000

Fecal Coliform in the Charles River

Fecal coliform levels stayed about the same in the Charles River from 1997 to 2000

1997 2000

Summary of Changes in Water Quality of the

Charles RiverThere was a slight increase in fecal coliform counts and phosphorus in the Charles

from 1997 to 2000.

There were major improvements in nitrogen and chlorophyll-a levels in the Charles from 1997 to

2000.

        

                           A new bridge, part of Boston’s Big Dig, crosses the Charles downtown

References

Taylor, D. 2001. Comparison of water quality in Boston Harbor before and after inter-island transfer. Boston: Massachusetts Water Resources Authority. Report ENQUAD 2001-09. 104 p. Zago, C., Giblin, A.E., and Bergamasco, A. 2001. Changes in the metal content of surficial sediments of Boston Harbor since the cessation of sludge discharge. Marine Environmental Research, vol. 51, pp. 389-415. Charles River Watershed Authority, www.crwa.org

A dog enjoys a day by the banks of the Charles