suggest broad questions to consider prior to model selection, including both
technical and decision-making issues that should be addressed by all the
parties involved in a 316(b). We use a tree of aquatic-impact-assessment
measures and corresponding methods to summarize modeling approaches,
with the suggestion that modeling choices be made to balance scientific
standards and policy-making needs. We recommend EPA’s ecological-riskassessment framework as an approach for effectively guiding 316(b) assessments and the role for modeling. Finally, we consider the challenges of
agreeing on management objectives, endpoints, measures, and risk criteria,
and we make five recommendations for 316(b) that provide a useful perspective for the role of modeling.
3. Modeling Fish Entrainment and Impingement Impacts
49
Sidebar 3.2
Hierarchy of terms needed for
environmental decision making
The EPA’s framework for ecological risk assessment (USEPA 1998,
2001) uses a hierarchy of five terms that we have adhered to throughout this chapter. Whether or not this framework is used, specifying
the equivalent of these five terms is a critical step in any decisionmaking process. A management goal is a general statement of the
desired condition or direction of preference for the entity to be
protected. It is often developed independently of any specific risk
assessment, such as part of federal or state legislation [e.g., 316(b)
regulations and guidelines]. A management objective is a specific
statement about something one desires to achieve that includes an
ecological entity targeted for protection and a direction of preference.
It is commonly derived from a management goal on an assessmentspecific basis. An assessment endpoint (or just endpoint in this paper)
is an explicit expression of what is to be protected. It is defined by an
ecological entity and the entity’s attributes, ideally including spatial
and temporal extent.
The EPA defines three classes of measures. Collectively, these
measures are used to describe an endpoint or factors affecting risk
to that endpoint. Measures of exposure characterize the existence
and movement of a stressor in the environment and its contact or
cooccurrence with the endpoint. Measures of effect describe a
change in an attribute of an endpoint, or its surrogate, in response to a stressor to which it is exposed. Measures of ecosystem
and receptor characteristics describe factors that influence the
behavior and location of ecological entities, the distribution of a
stressor, and life-history characteristics of the endpoint that may
technical and decision-making issues that should be addressed by all the
parties involved in a 316(b). We use a tree of aquatic-impact-assessment
measures and corresponding methods to summarize modeling approaches,
with the suggestion that modeling choices be made to balance scientific
standards and policy-making needs. We recommend EPA’s ecological-riskassessment framework as an approach for effectively guiding 316(b) assessments and the role for modeling. Finally, we consider the challenges of
agreeing on management objectives, endpoints, measures, and risk criteria,
and we make five recommendations for 316(b) that provide a useful perspective for the role of modeling.
3. Modeling Fish Entrainment and Impingement Impacts
49
Sidebar 3.2
Hierarchy of terms needed for
environmental decision making
The EPA’s framework for ecological risk assessment (USEPA 1998,
2001) uses a hierarchy of five terms that we have adhered to throughout this chapter. Whether or not this framework is used, specifying
the equivalent of these five terms is a critical step in any decisionmaking process. A management goal is a general statement of the
desired condition or direction of preference for the entity to be
protected. It is often developed independently of any specific risk
assessment, such as part of federal or state legislation [e.g., 316(b)
regulations and guidelines]. A management objective is a specific
statement about something one desires to achieve that includes an
ecological entity targeted for protection and a direction of preference.
It is commonly derived from a management goal on an assessmentspecific basis. An assessment endpoint (or just endpoint in this paper)
is an explicit expression of what is to be protected. It is defined by an
ecological entity and the entity’s attributes, ideally including spatial
and temporal extent.
The EPA defines three classes of measures. Collectively, these
measures are used to describe an endpoint or factors affecting risk
to that endpoint. Measures of exposure characterize the existence
and movement of a stressor in the environment and its contact or
cooccurrence with the endpoint. Measures of effect describe a
change in an attribute of an endpoint, or its surrogate, in response to a stressor to which it is exposed. Measures of ecosystem
and receptor characteristics describe factors that influence the
behavior and location of ecological entities, the distribution of a
stressor, and life-history characteristics of the endpoint that may