Title IV has been quite successful at
effectively reducing emissions of SO2 and NOx
from power generation to the levels set
by Congress. In fact, by 2020 emissions
from power plants are expected to be less
than half of the total SO2 emissions in the
U.S. As a result of these emission reductions,
some acid-sensitive areas are already beginning to show signs of recovery.
Full implementation of Title IV, and the pas-
sage of time needed for affected
ecosystems to respond to the new
environmental conditions, are expected to al-
low more areas to recover. However, several
scientific studies indicate that the emission
reductions achieved by Title IV are not suffi-
cient to allow recovery of acid-sensitive
ecosystems. Estimates from the literature of
the scope of additional emission reductions
that are necessary in order to protect acid-
sensitive ecosystems range from
approximately 40–80% beyond full
implementation of Title IV, with the most re-
cent studies focusing on the largest reduc-
tions. This report analyzes the impacts of a
range of levels that would achieve fuller en-
vironmental recovery from acid rain and
greater avoidance of the adverse ecological
effects associated with acid deposition.
The results of the modeling presented in
this Report to Congress indicate that
broader recovery is not predicted without
additional emission reductions.
Elimination of all SO2
emissions from power plants, how-
ever, will not fully protect all acid-sensitive
ecosystems affected by acid deposition; re-
ductions from other source categories would
be needed.
The information requested by
Congress and presented here represents
part of what is needed when determining
appropriate future actions; other information
includes the costs and other impacts of
emission reductions and
the value the public
places on further improvements to the envi-
ronment and human health.
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