However, more realistic and thus more complex models have not always
proved as effective as simpler models in contributing to the decisionmaking process (see Sidebar 3.1). With the renewed interest in 316(b)
decisions, modelers should carefully revisit the tradeoffs involved in
increasing model complexity.
The “stopping-time” problem for scientists is to judge when stakeholders and decision makers can no longer benefit from additional data
collection, analysis, or modeling. When to stop depends on the values at
stake (e.g., the low cost of modifying existing traveling screens versus the
high cost of switching from once-through cooling to closed-cycle cooling).
Scientists, particularly those involved in modeling, must also be sensitive to
recognizing when decision makers or stakeholders are effectively asking for
unverifiable predictions as a means of imposing a needed policy judgment
onto the science base. For assessments of entrainment and impingement,
the challenge is evaluating an often modest increase in mortality against a
background of high natural variability and other confounding factors. High
natural variability frequently negates the value of scientific information in
the decision-making process, such as occurred in attempts to attribute bird
mortality to the Exxon Valdez oil spill (Wiens 1996).
As far as resolving the most contentious debates between the parties,
scientists usually have no “silver bullet” to settle litigious disputes. The
many reasonable options scientists can provide may just reinforce some
stakeholders’ wish (on all sides of fish protection disputes) to make 316(b)
decisions through the courts. The only real solution for this dilemma is for
stakeholders and regulators to develop an environment of trust in which
models, endpoints, and associated measures and decision criteria can be
proposed, criticized, and modified in the decision-making process. Indeed,
this solution is what has happened with some site-specific 316(b) decision
making [e.g., Barnthouse (1988)]. For almost three decades, no “official”
316(b) regulatory guidance has been provided, but regulators nonetheless
have apparently often been able to make reasonable decisions.
3.4 Tree of Aquatic-Impact-Assessment Measures and
Site Specificity
At the same time that scientists are interacting with decision makers and
stakeholders, they are answerable to the scientific community for the
choices made. Thus, some kind of schematic organization of modeling
choices is required to indicate roughly where modeling complexity should
start and end, given the decision-making context. Such an organization of
modeling space is also a useful means for communicating among scientists,
regulators, and stakeholders the menu of options and the advantages and
disadvantages of those options.
3. Modeling Fish Entrainment and Impingement Impacts
57
proved as effective as simpler models in contributing to the decisionmaking process (see Sidebar 3.1). With the renewed interest in 316(b)
decisions, modelers should carefully revisit the tradeoffs involved in
increasing model complexity.
The “stopping-time” problem for scientists is to judge when stakeholders and decision makers can no longer benefit from additional data
collection, analysis, or modeling. When to stop depends on the values at
stake (e.g., the low cost of modifying existing traveling screens versus the
high cost of switching from once-through cooling to closed-cycle cooling).
Scientists, particularly those involved in modeling, must also be sensitive to
recognizing when decision makers or stakeholders are effectively asking for
unverifiable predictions as a means of imposing a needed policy judgment
onto the science base. For assessments of entrainment and impingement,
the challenge is evaluating an often modest increase in mortality against a
background of high natural variability and other confounding factors. High
natural variability frequently negates the value of scientific information in
the decision-making process, such as occurred in attempts to attribute bird
mortality to the Exxon Valdez oil spill (Wiens 1996).
As far as resolving the most contentious debates between the parties,
scientists usually have no “silver bullet” to settle litigious disputes. The
many reasonable options scientists can provide may just reinforce some
stakeholders’ wish (on all sides of fish protection disputes) to make 316(b)
decisions through the courts. The only real solution for this dilemma is for
stakeholders and regulators to develop an environment of trust in which
models, endpoints, and associated measures and decision criteria can be
proposed, criticized, and modified in the decision-making process. Indeed,
this solution is what has happened with some site-specific 316(b) decision
making [e.g., Barnthouse (1988)]. For almost three decades, no “official”
316(b) regulatory guidance has been provided, but regulators nonetheless
have apparently often been able to make reasonable decisions.
3.4 Tree of Aquatic-Impact-Assessment Measures and
Site Specificity
At the same time that scientists are interacting with decision makers and
stakeholders, they are answerable to the scientific community for the
choices made. Thus, some kind of schematic organization of modeling
choices is required to indicate roughly where modeling complexity should
start and end, given the decision-making context. Such an organization of
modeling space is also a useful means for communicating among scientists,
regulators, and stakeholders the menu of options and the advantages and
disadvantages of those options.
3. Modeling Fish Entrainment and Impingement Impacts
57