Conducting the Environmental Impact Analysis and Assessment - Environmental Impact Analysis: Process and Methods - page 219

concurrent with the highway development. Investigation revealed that
the decline was due to significantly increased hunting success, by tak-
ing advantage of the funneling of deer through the underpass.

The deficiencies of only considering mitigation following comprehensive
environmental analysis, and only for the proposed action, are the primary
causes of the environmental protection missteps illustrated by these exam-
ples. Another shortcoming of after-the-fact mitigation is that it frequently
is not a factor in the alternative selection and comparison. If a particular
alternative has numerous cost, performance, and environmental attributes
but an environmental impact fatal flaw (such as generating noise above a
significance criterion), it might be dismissed and a less advantageous alter-
native in every way but noise selected. If a measure to mitigate noise to an
acceptable level had been developed and incorporated earlier in the process,
the designated proposed action may have been different, more environmen-
tally beneficial, and preferable to all stakeholders. Given these downsides of
the classic mitigation approach, it is not surprising that a more proactive and
integrated approach has been developed.

5.4.2 Integrated and Proactive Approach to Mitigation

As environmental impact analysis matured, the shortcomings of after-the-
fact mitigation outlined above became apparent, and a more progressive
approach evolved. The enhanced approach centers on identifying impacts
early in the process, even at the initial impact prediction conceptual model
(see Section 5.3.1) and the scoping stages (see Section 4.3). Once the potential
for substantial impact has been identified, existing alternatives can be modi-
fied or new alternatives developed that mitigate the anticipated impacts.
This approach addresses most of the disadvantages of the classic approach
and most importantly it supports a full evaluation and comparison of both
the positive and negative aspects of the mitigation measures.
The integrated approach produces a full range of alternatives, some with
and some without mitigation. The prediction of impacts for some alterna-
tives reflects consequences without mitigation, and some reflect the mitiga-
tion, both on the target impact and collateral damage to other environmental
resources. This supports a full, concurrent, and relatively equal evaluation of
all impacts of all alternatives and associated mitigation, taking advantage of
impact prediction tools and approaches discussed above including:

r Application of impact significance criteria
r Review of prediction methods and results by the CAC and TAC
r Modeling that includes all aspects of an alternative, including
mitigation
r Design of affected environment investigations to support impact
prediction with and without mitigation