by by Katie Lindstedt

At the mouth of the Charles River, where it meets
Boston Harbor, the water seems clear, the river
picturesque, the surface reflecting the city’s modest
skyline. But further down, the Charles’s 70-mile main stem
is an over-fertilized breeding ground for algae.
On September 30, a 10-year study by the Charles River
Watershed Association—a nonprofit environmental organi-
zation—confirmed the river’s overabundance of nutrients.
High levels of phosphorous—an important nutrient—has
over-fertilized the aquatic ecosystem, causing runaway
planktonic growth that renders the waterway toxic to its
larger organisms and unappealing to fishers. The Massachu-
setts Department of Environmental Protection and the US
Environmental Protection Agency released a draft report on
September 30 that calls for cutting the annual phosphorous
levels of the river’s upper and middle portions by 49 percent.
If the draft report is finalized, municipalities in the
Charles’s vicinity would have to take measures to reduce
phosphorous contributions from stormwater runoff and
wastewater treatment facilities. The proposed limits pertain
to the towns located in the river’s watershed—Medway, Mil-
lis, Needham, Waltham, and Wellesley—and portions of
28 more, including Arlington, Lexington, Brookline, and
Newton. The state agency is accepting written comments on
the plan through November 30.

Reaching the limit
Nutrients are vital to all organisms and ecosystems. A nutri-
ent is a chemical that an organism needs to live and grow,
a substance that enriches the body, like carbohydrates, fats,
proteins, vitamins, and inorganic chemical compounds like
water and oxygen. In freshwater ecosystems like the Charles,
phosphorous is what environmental scientists refer to as the
limiting nutrient. It is the ecosystem’s scarcest nutrient and
limits primary organism reproduction. Normally, the prima-
ry organisms cannot reproduce beyond what is allowed given
the quantity of phosphorous. When there are large levels of
the limiting nutrient, the primary organism—algae, in the
case of aquatic ecosystems—growth explodes.
The river’s current phosphorous level has environmental,
aesthetic, and recreational ramifications. The waterway is
“choked by weeds and huge blooms of algae,” according to
Kate Bowditch, the Charles River Watershed Association’s
Director of Programs. The speed of vegetation growth stress-
es the river’s fish populations. The Charles also contains a
toxic cyanobacteria masquerading as an ordinary blue-green
algal bloom. Three years ago, one such toxic bloom led to the
postponement of a swimming race.
A Total Maximum Daily Load Analysis (TMDL)—a cal-
culation of the maximum amount of a pollutant that a water
body can receive and still meet water quality standards—of
nutrients in the Charles River’s upper and middle sections
began in 2000. The Federal Clean Water Act of 1972 re-
quires that states undertake a TMDL when a body of water is
severely impaired. The river’s nutrient levels currently exceed
federal water quality standards.

Straight to the source
Phosphorous is abundant in the natural environment, but
polluting levels are reached from “combined sewer overflows
(CSOs), wastewater discharges, stormwater runoff, accu-
mulated organic sediments on the river bottom, and some
groundwater sources,” according to the report.
Among these sources, wastewater, stormwater, and ben-
thic sediments are the primary human sources of phospho-
rous in the Charles. Stormwater is the leading source of the
Charles’s phosphorous, both during the summer and winter.
In the summer months, stormwater contributes to 78 per-
cent of the river’s phosphorous; wastewater and benthic sedi-
ment—the underwater accumulation of organic sediments
that release nutrients—contribute 16 percent and seven
percent, respectively. During winter, stormwater is still the
leading source of phosphorous at 70 percent; wastewater is
22 percent, and benthic sediment is seven percent.
Stormwater runoff from rooftops, driveways, roadways,
and vegetated areas “carries phosphorous that is adsorbed”—
accumulated on the water’s surface—“to sediment and dis-
solved in the water,” according to the report.
Many human activities are known to raise the level of
phosphorous in stormwater, particularly the use of lawn
fertilizers, car wash products, and certain detergents. Car
exhaust, other oil byproducts, pet waste, and lawn clippings
are additional sources of phosphorous.
All municipalities would be required to regularly renew
their stormwater drain permits with the EPA. The Massachu-
setts Department of Transportation would be responsible for
reducing the phosphorous that washes off of roadways and
contributes to the nutrient’s presence in stormwater runoff.
Bowditch suggested more frequent street sweeping as one
possible measure to cut the phosphorous in roadways.

A waste...of money
The draft calls on wastewater treatment facilities to reduce
phosphorous by approximately 65 percent. A reduction this high will be costly, and operators at several facilities expressed
financial concerns.
“It’s just a major reduction. We’re going to have to take
low-interest loans out to pay for it,” Cheri Cousens, an
engineer and assistant chief operator for the Charles River
Pollution Control District, said. “I’m just not sure if that
reduction is necessary.” Cousens noted that her plant has
already reduced its phosphorous levels in accordance with
federal standards.
But Ken Feeney, the superintendent of Medfield’s Depart-
ment of Public Works, is less concerned. “Phosphorous is the
easiest nutrient to remove,” Feeney told the boston globe.
Others are concerned about the actual process of elimi-
nating phosphorous. While Peter Iafolla, the chief operator
of Medfield’s wastewater plant, agrees that phosphorous is
the easiest nutrient to remove, he noted that the required
chemicals are expensive and dangerous.
But Bowdich does not think that money should even be
a point of contention.
“Every time we’ve taken significant changes to clean up
our rivers and streams, people have been very anxious about
the cost, and people have been very unsure about whether
the results were going to succeed and whether it was going to
have a beneficial impact. Especially in the case of clean water,
it has succeeded,” Bowditch said.
She noted that representatives from treatment facilities
suggested that tackling the stormwater problem should be
the top priority. “They feel like stormwater is the biggest
problem, so why don’t we just go back and talk to them
when we’ve cleaned the stormwater? We did a simulation
that showed even if we did everything that we thought could
be done to clean up the storm water, it still wouldn’t be
enough to reach the target levels of phosphorous,” Bowditch
said. “The only way to reach the targets was to reduce the
phosphorous in the wastewater plants.”
Fish and humans both have a stake in the water quality of
the Charles River. The algal blooms’ stress puts a stress on the
entire ecosystem. Bowditch noted that there is a tremendous
amount of sedimentation at the bottom of the river, because
“year after year, the plant material dies and settles. We’ve lost
a lot of the good bottom environment for fish.”
“There are obvious ecosystem impacts as well as human
recreation and public health impacts,” she said. “It’s very
clear that if we don’t take these measures to reduce the phos-
phorous now, we’re never going to make any progress on the
It’s not clean unless KATIE LINDSTEDT B'11 can take
a bath in it.