indicators for aquatic stressors and by developing additional decision support tools as needed. In 
this approach, the SI process is iterative, usually beginning with retrospective analysis of 
available data, and includes the identification of stressors that might be causing the impairment. 
Figure 2. Manager’s decision support system to protect and restore aquatic resources 
using ORD’s research products (SI box is modified from EPA 2000b). 
Stressor identification consists of three main steps, the core of the SI process: 1) listing candidate 
causes of impairment, 2) analyzing these candidate causes, and 3) producing a causal character¬ 
ization. The support system also involves interactions with decision makers and stakeholders to 
assist in forecasting the effects of the stressors and in taking remediation action, if needed. 
Remediation requires, first, criteria for what is acceptable in a given environment, and second, 
the models necessary to link changes in stressors with improvements in the system. Additional 
information is provided in Section 8 (Diagnostics) of this document concerning the development 
of a framework for a decision support system. NHEERL-generated products from this research 
will be combined with exposure models and with restoration and remediation techniques 
developed by the National Exposure Research Laboratory (NERL) and National Risk 
Management Research Laboratory (NRMRL), respectively, to meet management needs. 
6 
