Snow Pond
/ Messalonskee Lake Association

How’s
The Water?
“Come on in, unless you’re a phosphorus molecule!”
If
you’ve ever seen someone anchored near the New England Music Camp
who seems to be messing with equipment other than fishing rods, that
would be me. For the past eight years I’ve been a volunteer water
quality monitor for Messalonskee Lake. Every 2 weeks during the summer
I drop anchor at station #1, the “deep hole” near the New
England Music Camp, to record data and collect water samples for additional
testing. I was trained by the Maine Volunteer Lakes Monitoring Program
(VLMP), a non-profit citizens group that has partnered with the Maine
Department of Environmental Protection to collect water quality data
on Maine lakes since 1970. While DEP employees do some of the data-gathering,
most of the data has been obtained through the years by VLMP-trained
volunteers.
So
what are we testing for? With so much attention focused on Milfoil these
days, it’s easy to forget about another threat to our continued
enjoyment of Messalonskee Lake. “Eutrophication” refers
to the increase of plant nutrients (such as phosphorus and nitrogen)
in a body of water. Phosphorus is usually a limiting nutrient to plant
growth in a lake, meaning that plant growth increases at the same rate
as phosphorus is added to the system. And the plants we are most concerned
about in this case are not milfoil, but the various species of algae:
the source of those notorious algae blooms that cause some otherwise
beautiful lakes around here to occasionally turn green and murky during
the summer. (I won’t name names. They know who they are.)
Phosphorus
content since I began collecting samples in 2001 has been fairly stable,
ranging from 10 to 14 parts per billion (ppb). It’s hard to know
if this stability is a result of improved landscaping practices and
drainage conditions around the lake, but it is encouraging that conditions
do not appear to be getting worse, especially given the increased development
on the lake during these years.
In
addition to phosphorus content, I also measure dissolved oxygen and
water transparency. Dissolved oxygen levels in Messalonskee do seem
to be worsening over time. During spring overturn, when water is mixing
from the top to the bottom of the pond, oxygen levels are high at all
depths. In Messalonskee, we see a mid-summer depletion of oxygen in
the water between 30 and 40 feet deep because decomposers like fungi
and bacteria are feasting on dead algal cells and thriving –-
but using up the oxygen in that zone. In other words, we’re back
to phosphorus again: increased phosphorus leads to increased algae,
which leads to oxygen depletion (as the algae are decomposed).
Decomposition
also leads to oxygen depletion in the deepest waters as well. For many
years Messalonskee has had higher oxygen levels in the water between
50 and 60 feet deep, which provides a refuge for cold water fish such
as salmon and trout. The duration of this refuge over the course of
the summer appears to be shrinking, a bad thing for the cold water fish.
Water
transparency is what most of us think of when we think about how “clean”
or clear the lake is. It is measured using a “Secchi Disk”.
Since algae are the most abundant particles in the lake, transparency
is an indirect measure of algae growth. Secchi disk readings on Messalonskee
range from about 4-7 meters (13-23 ft) through the course of the summer.
The best Secchi reading since 1970 was 7.5 meters (24 feet), recorded
in 1971, and the worst was 3.9 meters (13 feet), in 1997. The best reading
I got last summer was 5.7 meters (19 feet).
You
can see all the data that has been collected on Messalonskee Lake since
1970 by going to www.pearl.maine.edu. Messalonskee Lake has had 3 testing
stations, but in recent years only station number 1 has been monitored
on a regular basis. If you would like to consider becoming a volunteer
monitor to collect data at one of the other stations on our lake, please
feel free to contact me via the e-mail address in this newsletter, or
contact the Maine VLMP through their web site or by phone (783-7733).
If
becoming a volunteer lake monitor is not your cup of tea, there are
still three things that every landowner can do to prevent phosphorus
buildup in the lake: 1) landscape your property to reduce erosion and
runoff into the lake, 2) avoid using fertilizer on your lawn, and 3)
make sure your septic system is well maintained. There is no successful
method for removing phosphorus from a lake once it has entered; the
only way to prevent an algae bloom is to decrease phosphorus loading
before it is too late. Unlike some other nearby lakes, Messalonskee
has not yet had an algae bloom. Let’s do everything we can to
keep it that way!
--
Gilliam Johnston
(With thanks to Linda Bacon, Maine DEP employee and lifetime denizen
of Messalonskee Lake.)