This document summarizes a passage about the history and current state of water quality in the Penobscot River in Maine. It discusses how the river was heavily polluted 50 years ago but has since greatly improved due to the Clean Water Act of 1972. It is now rated Class B and supports many uses, though some legacy pollution remains. The river is monitored ongoingly to protect water quality.

1. The following pages contain content for an app designed to highlight the science surrounding us, as
well as promote the integration of science and literacy learning. The left column contains the content
as the lead scientist wrote it. The right contains my writing.
The app is titled Science Around ME, and is an initiative of the Maine Intersections partnership. It can
be found here: http://cognitivex.com/clients/ScienceAroundMaine
-Elijah Merrill

2. Before Rewrite
Water Quality
Fifty years ago, the Penobscot River was so pol-
luted and rank that it drove people from its banks.
The Bangor waterfront was an industrial waste-
land, with coal tar and oil leaking into the river.
Industrial waste from pulp and paper mills and un-
treated sewage from growing cities and towns
churned foamy and dark brown in the Penobscot.
However, in 1972 Maine Senator Ed Muskie
wrote and sponsored the Clean Water Act, which
forced the clean up of all our nation’s rivers, in-
cluding the Penobscot. The law funded construc-
tion of wastewater treatment plants and set strict
limits for pollutants. By 1980 the Environmental
Protection Agency declared the Penobscot a “wa-
ter quality success story.”
The State of Maine classifies its river water qual-
ity, and only the cleanest, purest waters are rated
AA or A. Waters used by industry generally are
designated Class C - usually because of reduced
dissolved oxygen resulting from phosphorous dis-
charge. However, the Penobscot River at Bangor
is rated Class B: suitable for drinking (after treat-
ment), fishing, recreation in and on the water, and
as habitat for native fish and other aquatic life.
Dissolved oxygen is a key measure of water qual-
ity. The Maine Department of Environmental Pro-
tection and the Penobscot Indian Nation monitor
the Penobscot River and keep track of pollution.
There are times when the Penobscot River does
not meet the Class B standard and the dissolved
oxygen dips below the required seven parts per
million needed by Atlantic salmon and other ani-
mals. This usually happens in the summer months
when there hasn’t been much rain and the river is
low, and algae begin to grow and consume oxy-
gen. The algae are fueled by nutrients, in particu-
lar phosphorus, which mostly comes from pulp
and paper mills and wastewater treatment plants.
In 2004, the Penobscot Nation tracked a massive
algae bloom that originated at Dolby Pond in
Millinocket and stretched the entire length of the
After Rewrite
Into the River: a Success Story
Heraclitus famously stated that a man cannot step
into the same river twice. The phrase uses the
nature of a river to speak of the ever-changing
character of the universe. But for us it also
describes the storied health of the Penobscot—it's
the same river now as it was when Bangor was
first founded, but is it really?
The river has been utilized by humans for
centuries. Unfortunately, the more prosperous
Bangor became, the less healthy the river was. By
the 1950s the stink of the river drove people from
its ripples and eddies. The water churned—with
pollutants like coal tar, oil, and untreated sewage
from spreading communities, as well as industrial
waste from paper mills, which increased as the
river flowed south. The water was so bad, the
adage went, that you wouldn't have to worry
about drowning if you fell in the Penobscot.
In 1972, during an era of environmental focus,
Senator Ed Muskie took a leading role in cleaning
up our rivers. He wrote and sponsored the Clean
Water Act, which protected the nation's rivers
from further ruination. The Penobscot River was
ripe for rehabilitation. The law funded
construction of wastewater treatment plants and
set strict limits on pollutants, which both had a
great impact on the river. Just eight years after
Senator Muskie's bill passed (1980) the
Environmental Protection Agency declared the
Penobscot a “water quality success story.”
Don't assume that a river is dirty just because it
looks like it is. Many things effect the water's
appearance. For instance, water might have a
brown tint because of naturally occurring organic
compounds, deposited by decomposing plant
matter; rivers that are fed by wetlands are
especially dark, for this reason. Rivers are
actually tested and given a rating. The rating is
determined by several factors that the eye can't
measure, such as the amount of dissolved oxygen
in the water, and, of course, the presence of

3. river, presumed to be caused by the release of
phosphorus. Since new rules were put in place in
2011, mills and other permitted wastewater
sources have reduced the amount of phosphorus
they discharge to the river. Cold water holds more
oxygen than warm water; in recent years, water
temperature in the summer has been too warm for
Atlantic salmon and other cold-water species.
No longer is the Penobscot River’s water color a
reflection of pollution. The river’s tint is a natural
product of dissolved organic carbon, which comes
from wetlands, leaf litter, organic matter breaking
down within the river, and wastewater. The
Penobscot has average organic carbon content,
and significantly less than rivers to the east which
drain large wetland areas and tend to be darker as
a result.
So, how clean is the Penobscot? Dramatically
cleaner than it used to be. Swimmable? Most of
the time. Drinkable? With minimal treatment.
Fishable? Yes, but follow state guidelines for fish
harvest and eating, as a legacy of historic mercury
and dioxin pollution persists in the river’s food
web.
After Rewrite
pollutants. One of these pollutants, phosphorous,
feeds algae, which themselves consume oxygen.
This is bad for fish—they breath the oxygen
suspended in the water. Once, there was an algae
bloom that stretched all the way from Millinocket
south. Since new rules were put in place in 2011,
mills and other permitted wastewater sources have
reduced the amount of phosphorus they discharge
to the river. In addition, the oxygen level of the
river is also effected by its temperature. Cold
water holds more oxygen than warm. In recent
years, water temperature in the summer has been
too warm for Atlantic salmon and other cold-water
species.
The river is monitored by the Maine Department
of Environmental Protection and the Penobscot
Indian Nation. In the state of Maine clean water is
given a grade of A or AA. Waters used by
industry are often designated Class C—usually
because of a lack of oxygen. At Bangor the
Penobscot River is rated a B: suitable for drinking
(after treatment), fishing, recreation—in and on
the water—and as habitat for native fish and other
aquatic life. The river has come a long way since
before there were protections for it. You can not
only fall in it, you can swim as well—with care.
But you still can't step in the same river twice.