Transcript A GIS Analysis of Boston Harbor and the Charles River Boston, Massachusetts

A GIS Analysis of Boston
Harbor and the Charles River
Boston, Massachusetts
Amy Townsend-Small
GIS in Water Resources
Fall 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”.
Artist’s rendition of the Boston Tea Party, 1773
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.
Monitoring the Pollution of
the Waters of Boston Harbor
In 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
Cambridge
Charles River
Inner
Boston Harbor
Deer Island Wastewater Treatment Facility
Deer Island Effluent Discharge Site
Boston
Former Nut Island Effluent Discharge Site
Nut Island Wastewater Treatment Facility
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
Before
After
Concentrations of DIN decrease after the transfer of sewage effluent to the new site
Total Nitrogen in Boston
Harbor
Before
After
Concentrations of total nitrogen decrease after the transfer of sewage effluent to the new site
Dissolved Inorganic
Phosphorus in Boston Harbor
Before
After
Concentrations of DIP increase after the transfer of sewage effluent to the new site
Total Phosphorus in Boston
Harbor
Before
After
Concentrations of total phosphorus increase after the transfer of sewage effluent to the new site
Chlorophyll-a in Boston
Harbor
Before
After
Standing stocks of chlorophyll-a increased after the transfer of sewage effluent to the new site
Dissolved Oxygen in Boston
Harbor
Before
After
Dissolved oxygen decreased in saturation after the transfer of sewage effluent to the new site
Fecal Coliform in Boston
Harbor
Before
After
Fecal coliform counts decreased after the transfer of sewage effluent to the new site
Water Clarity in Boston
Harbor
Before
After
Water clarity improved after the transfer of sewage effluent to the new site
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
Harbor
In 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.
Deer Island
! Effluent Discharge Site
^
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?
Sediment
Sampling Site #1
Sediment
Sampling Site #2
Former
Nut Island
Sludge Discharge Site
Lead in Boston Harbor
Sediments
1991
1998
Generally, lead concentrations decreased in the former sludge dumping site and increased in the
site closer to shore.
Copper in Boston Harbor
Sediments
1991
1998
Copper concentrations in the sediments decreased in the former sludge dumping site, and copper
concentrations increased in the site closer to shore.
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 Sediments
Since 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.
Logan Airport
Deer Island
! Effluent Discharge Site
^
Charles River
Sediment
Sampling Site #1
Sediment
Sampling Site #2
Former
Nut Island
Sludge Discharge Site
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?
Cambridge
Boston
Boston
Harbor
Total Phosphorus in the
Charles River
1997
2000
There is a slight increase in total phosphorus levels in the Charles River between 1997 and 2000.
Total Nitrogen in the Charles
River
1997
2000
There was a general decrease in nitrogen in the Charles River from 1997 to 2000
Chlorophyll-a in the Charles
River
1997
2000
There was a marked decrease in chlorophyll-a concentrations from 1997 to 2000
Fecal Coliform in the Charles
River
1997
2000
Fecal coliform levels stayed about the same in the Charles River from 1997 to 2000
Summary of Changes in Water
Quality of the Charles River
There 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