By
Craig Bailey
On
Tuesday, May 7, over 20 people from the community attended a tour of Portland
Water District’s (PWD) Sebago Lake Water Treatment Facility. The tour was
offered in support of National Drinking Water Week to call the public’s
attention to water quality and PWD’s approach to protection, treatment and
testing of the water supply to 15% of Maine’s population.
The
tour was kicked off by Kirsten Ness, PWD’s Water Resource Specialist,
reinforcing her role in protecting Sebago Lake, the number of customers served,
the reasons why the lake water is of such high quality and related challenges.
Ness began
by stating, “PWD serves approximately 200,000 people across 11 communities. As
such, Sebago Lake water quality is of utmost importance.”
Ness
further shared, “The lake is over 300 feet deep and contains almost 1 trillion
gallons of water, which is considered of excellent quality. The lake contains
so much water you could fill enough Poland Springs tanker trucks to get to the
moon and back - twice!”
The
source of water in Sebago Lake comes from the Sebago Lake Watershed, which is
more than 50 miles long, stretching from Bethel to Standish and includes parts
of 24 towns including the towns of Windham and Raymond. As such, whatever
happens in the watershed ultimately impacts Sebago Lake.
Ness
reinforced, “One of the reasons for such high water-quality is the watershed is
84% forested, serving as a natural filter. The result: the lake water is clean
enough to be exempt from the expensive filtration process required of most
surface water sources.”
A key
challenge to maintaining water quality is only 10% of the lake is restricted.
This results from a law passed in 1913 prohibiting bodily contact within two
miles of the intakes and prohibiting trespassing on District lands acquired
"for the purpose of protecting the purity of the waters." Later
amendments prohibit trespassing within 3000 feet of the intakes.
One of
the visitors asked what Ness confirmed was a common question, “Why can we boat
within the two-mile zone but not swim?” Ness responded by sharing, “Petroleum
products ‘mainly’ evaporate off the surface and our water intakes are deep in
the lake. The PWD is more concerned with what we humans carry and excrete.”
Ness further
shared, “We have a beach monitoring program and have consistently found that E.
coli levels are much lower within the two-mile limit than at swimmable
beaches.”
Dave
Herzig, PWD’s Plant Systems Foreman then shared an overview of his role in
operating the treatment facility as well as additional factors contributing to
the quality of water. Herzig mentions, “When we meet with people from other
water-treatment facilities we hear common challenges including: shallow lakes,
shallow water intakes, algae blooms and rapid changes in river flow. We simply
don’t face any of these challenges. In fact, Sebago is protected thermally (via
stratification or layers of varying temperatures and densities) nine months of
the year. As such, high wind events, pollen bloom and other natural events
don’t affect the lake as it does others.”
During
the tour of the treatment plant Herzig shared, “In the peak of summer PWD
treats approximately 30 million gallons of water per day and during winter
around 19 million gallons per day. Treatment occurs in three ways: ozone, ultra
violet light (UV), and chloramines.”
Further,
Herzig reinforced, “Because our water is so ridiculously clean our treatment
facility is a bit over-sized. As a result, we are prepared to effectively
handle decreases in water quality should that occur.” The visitors agreed this
is a good position to be in!
Mike
Koza, PWD’s Lab Manager, shared an overview of his role and led a tour of the
lab. Koza reinforced, “PWD tests and monitors the quality of water in the Sebago
Lake Watershed, the output of the treatment system as well as numerous sampling
sites within the distribution system, containing 1,000 miles of pipe supplying
customers.”
Automatic
instrumentation is in place which is monitored by lab technicians who also
perform lab testing to confirm meter readings. In addition, there are over 45
sampling sites including: fire stations, convenience stores, town halls, post
offices, and other readily accessible establishments.
A
primary focus of distribution system monitoring is Coliform which, if found,
can be an indicator of other bacteria. The good news is that, as Koza states,
“we haven’t found any in years.”
Koza responded
to questions related to emerging risks that residents along the watershed
should be aware of. This includes micro plastics and pharmaceuticals, which can
leech into the lake as a result of doing laundry (traces of microfleece have
been found in fish from other bodies of water) and flushing (trace amounts of
Advil have been found in Sebago).
PWD’s
highly qualified lab technicians use leading-edge technology (some of which is locally
sourced from IDEXX).
In
addition to the tour, PWD is offering a Brewery Collaborative where the public
can learn about the connection between forests, water, and beer. Visit pwd.org
for a full schedule of offerings and participating breweries.
