other parties might reject substitution of an intermediate endpoint, such as
equivalent adults lost, that does not reflect the potential dynamics of the
population. All parties might agree to its use, however, if coupled with
requirements for monitoring and reconsideration at each 5-year repermitting interval. Alternatively, the decision might be to make a more riskadverse decision rather than waiting until more refined knowledge is
available. That is the decision maker’s prerogative. While the scientist then
has little more to contribute, his or her prior input can critically influence
this overall decision process.
Regardless of the measures selected, the next step of agreeing on decision criteria for these measures is even more controversial. For example,
how many individual fish of a representative indicator species can be killed
by entrainment and impingement before some modification of the CWIS is
required? 1? 10
4 ? 10
9 ? Or what observed or predicted percentage reduction in year-class strength or in the adult population triggers the decision
that some modification of the CWIS is required to reduce losses from
entrainment and impingement? 1%? 10%? 20%?
Multiple answers to such questions are possible because they involve a
balancing of science, societal values, and politics (Keeney 1992; Lackey
1994, 1998, 1999). Such balancing becomes increasingly site specific if
the objectives of the stakeholders differ substantially. In addition, no single
scientifically sound basis exists for specifying measures and associated risk
criteria. The answer could depend on the water-body type (coastal, river,
estuary, lake, or reservoir) and how that resource has been locally managed
and valued. The same population impact on an already highly impacted
waterway could be considered differently from that occurring on a productive, previously unimpacted estuary. Indeed, clarifications of where, and
to what extent, such value judgments may matter should be a key policy
task.
3.7 Recommendations for 316(b) Assessments
Recommendations for guiding 316(b) assessments are emerging, especially
when the management objectives are focused on fish populations as the
endpoint (see Sidebar 3.2). These recommendations help place in a useful
perspective the role of modeling as part of any assessment of entrainment
and impingement. They also reflect an attempt to balance what is scientifically sound and what experience indicates will be accepted in the sociopolitical and legal process of 316(b) decision making.
1. We recommend that the 316(b) analysis plan capitalize on the
considerable body of knowledge that has accumulated during the past
three decades from assessments of entrainment and impingement and from
3. Modeling Fish Entrainment and Impingement Impacts
63
equivalent adults lost, that does not reflect the potential dynamics of the
population. All parties might agree to its use, however, if coupled with
requirements for monitoring and reconsideration at each 5-year repermitting interval. Alternatively, the decision might be to make a more riskadverse decision rather than waiting until more refined knowledge is
available. That is the decision maker’s prerogative. While the scientist then
has little more to contribute, his or her prior input can critically influence
this overall decision process.
Regardless of the measures selected, the next step of agreeing on decision criteria for these measures is even more controversial. For example,
how many individual fish of a representative indicator species can be killed
by entrainment and impingement before some modification of the CWIS is
required? 1? 10
4 ? 10
9 ? Or what observed or predicted percentage reduction in year-class strength or in the adult population triggers the decision
that some modification of the CWIS is required to reduce losses from
entrainment and impingement? 1%? 10%? 20%?
Multiple answers to such questions are possible because they involve a
balancing of science, societal values, and politics (Keeney 1992; Lackey
1994, 1998, 1999). Such balancing becomes increasingly site specific if
the objectives of the stakeholders differ substantially. In addition, no single
scientifically sound basis exists for specifying measures and associated risk
criteria. The answer could depend on the water-body type (coastal, river,
estuary, lake, or reservoir) and how that resource has been locally managed
and valued. The same population impact on an already highly impacted
waterway could be considered differently from that occurring on a productive, previously unimpacted estuary. Indeed, clarifications of where, and
to what extent, such value judgments may matter should be a key policy
task.
3.7 Recommendations for 316(b) Assessments
Recommendations for guiding 316(b) assessments are emerging, especially
when the management objectives are focused on fish populations as the
endpoint (see Sidebar 3.2). These recommendations help place in a useful
perspective the role of modeling as part of any assessment of entrainment
and impingement. They also reflect an attempt to balance what is scientifically sound and what experience indicates will be accepted in the sociopolitical and legal process of 316(b) decision making.
1. We recommend that the 316(b) analysis plan capitalize on the
considerable body of knowledge that has accumulated during the past
three decades from assessments of entrainment and impingement and from
3. Modeling Fish Entrainment and Impingement Impacts
63