Environmental Engineering Reference
In-Depth Information
major federal public works projects across the country because the new policy required a
pre-construction environmental assessment or environmental impact statement (EIS) that
evaluated potential environmental effects and considered the advantages of alternatives, in-
cluding the benefits of abandoning the given project. The assessment process also opened
a federal agency's entire construction process to two rounds of review. The first round was
an internal review to resolve interagency quarrels. For example, federal agencies such as
the Fish and Wildlife Service could weigh in on how a Corps project might impact the
agency's mandate to protect fish and wildlife. The second round was an external evaluation
that provided citizens with access to the same information used by agencies to complete
a project's initial assessment. The public could also submit formal responses that had to
be included in the public record, and if any aspect of an assessment was incomplete, they
to consider the environmental effects of their projects “in unprecedented detail.” Environ-
mental historian Jeffrey Stine's observation comes in the context of the Tennessee-Tombig-
bee Waterway, a massive navigation project that linked the Gulf of Mexico with the Ten-
nessee River via Alabama and eastern Mississippi. The Tenn-Tom was one of the Corps'
dam and reservoir was also subject to the EIS process not only once but multiple times.
Corps engineers began building Trotters Shoals after 1970, so Trotters was the Corps'
first Savannah River valley project subject to compliance with NEPA. Trotters's first EIS
laid bare the Sun Belt's water-quality challenges. Corps engineers defended the massive
Trotters Shoals dam and reservoir project in the
Draft Environmental Impact Statement
while simultaneously arguing that the project would produce complicated new envir-
onmental conditions. Artificial reservoirs are, after all, convoluted environments. These
working reservoirs do indeed create good fishery habitat and a new environment for
anglers, pleasure boaters, campers, swimmers, and second-home owners to appreciate. But
juggling the services—hydroelectric generation, flood control, and recreation—of the dams
and lakes also hindered the reservoirs' ecological functions. The new reservoir environ-
ment of the artificial lakes required technological solutions beyond hatchery science to
maintain new sport fisheries, and one of the most significant problems was insufficient
oxygen for aquatic organisms. Large artificial southeastern reservoirs behave differently
from natural lakes in colder regions. Whereas some lakes and reservoirs experience a cir-
culating inversion of hot and cold water twice a year (particularly lakes that have freeze-
thaw cycles), southeastern reservoirs typically experience a single seasonal inversion. This
single inversion, when combined with manipulated water levels and intensive solar heat
gain, leave southern reservoirs oxygen-poor. For example, the Savannah River's reservoirs
“stratify” during the summer and fall, and cold water sinks to the bottom and warm water
rises. By late fall and early winter, an inversion takes place that helps mix the water more
