Northern Georgia will soon have a new freshwater reservoir: Lake
McIntosh. The proposed 650-acre lake will sit on the border of Fayette
County and neighboring Coweta County, eventually providing more than 10
million gallons of drinking water per day.
But first, the Fayette County Water System must assure the United States
Fish and Wildlife Service (USFWS) that endangered mussels living in the
targeted creek will be safe.
To verify this, Atlanta-based CCR Environmental is conducting physical
and biological analyses of Line Creek, downstream of the proposed
reservoir. Part of this work will involve measuring dissolved oxygen
levels, which is being done with a HOBO U26 Dissolved
Oxygen data logger from Massachusetts-based Onset Computer
The amount of dissolved oxygen in a body of water is an indicator of its
health: high dissolved oxygen correlates with high biological
productivity, and low dissolved oxygen means lower biological
productivity. Because all animals, including mussels, require oxygen for
respiration, dissolved oxygen is an important indicator of the relative
health of an aquatic animal's environment.
Under the Endangered Species Act, the USFWS requires consultation for
any project that may affect federally-protected species or their
critical habitat. The Lake McIntosh project was determined to
potentially impact several federally-protected mussel species, including
the oval pigtoe (Pleurobema pyriforme), shinyrayed pocketbook (Hamiota
subangulata) and Gulf moccasinshell (<>Medionidus penicillatus).
According to CCR Aquatic Ecologist Chris Crow, the team previously
measured dissolved oxygen in the field with hand-held probes. "Our
option was to do it manually," Crow explained, "meaning that once a week
we had to go out to the site before dawn with a meter." It is general
practice to measure dissolved oxygen just before dawn, when levels are
at their lowest.
The Onset dissolved oxygen logger is self-contained, and can be deployed
and left to take measurements in a body of water, either fresh or
saltwater, for weeks at a time. It records dissolved oxygen levels as
often as the user chooses, and the data is time-stamped and downloadable
to a laptop computer or a hand-held data shuttle device offered by Onset.
The logger was deployed in sandy-bottomed Line Creek with the help of a
six-foot metal fence post. It was attached to the post with zip ties,
and fit vertically into the U-shaped groove in the post.
"It's important that the logger be placed in the deep part of the stream
in a well-mixed area, with the sensor down low enough so it's not going
to expose the probe if the water level drops," said Crow.
As expected, the collected data has shown that dissolved oxygen levels
were lowest in midsummer, when the creek's flow is lowest and
temperature is highest.
"We can see the highs and lows, and can see the diurnal [day/night]
cycle now, too," said Crow. "It's reassuring to confirm it's there."
The data will provide the dissolved oxygen information required by the
Fish and Wildlife Service, and will help determine how reduced stream
flow will affect dissolved oxygen - and by extension - the organisms in
the stream. The data will also serve as baseline data for habitat
comparison post-construction of the Lake McIntosh dam.
Onset is a leading supplier of data loggers. The company's HOBO data
logger and weather station products are used around the world in a broad
range of applications, including building energy performance monitoring,
water resources management, and ecological and agricultural research.
Based on Cape Cod, Massachusetts, Onset has sold more than 2.5 million
data loggers since the company's founding in 1981. Visit Onset on the
web at http://www.onsetcomp.com.
ABOUT CCR ENVIRONMENTAL
CCR Environmental, Inc. (CCR) is a small business that specializes in
ecological and natural resource studies. Since its founding in 1999 in
Atlanta, Georgia, the company has been providing quality, cost-effective
consulting services to government, industry, and other professional
firms across the southeast. The company routinely performs a variety of
biological/environmental impact studies, including protected species
surveys, fish and macro invertebrate assessments, water quality studies,
and jurisdictional waters delineations and permitting. Visit CCR on the
web at http://www.ccrenvironmental.com
or contact Mr. Crow at email@example.com.
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