establishing sediment criteria that support aquatic life in streams/rivers, lakes/reservoirs, 
wetlands, and estuaries. NHEERL's effort concerning suspended and bedded sediments has been 
redirected since this section was first written. The majority of the work in this research area will 
now occur under Goal 8 (EMAP) because EMAP design techniques will be applied to develop 
effect thresholds for suspended and bedded sediments in aquatic systems. Some of these 
techniques are described generally in the Critical Path subsection of this section. However, at 
this time, the effort under aquatic stressors will only include a literature review of suspended and 
bedded sediments research. Results from this review will be combined with EMAP approaches 
to synthesize and evaluate the state of the science. Once the review has been completed, data 
gaps will be identified and additional research will be conducted, if warranted. Additional goals 
and research topics are proposed, but will depend on the results of this combined effort. 
Section 7 focuses on developing methods to reduce uncertainty and significantly advance current 
methods to derive criteria for toxic chemicals. The general goal of this research is to develop 
scientifically-defensible methods for better characterizing the risks of toxic chemicals to aquatic 
and aquatic-dependent populations and communities. The key elements for improving aquatic 
risk assessments and criteria for toxic chemicals include providing methods to: improve criteria 
at the individual level based on improved characterization of risks, link individual-level data to 
population endpoints, support risk assessments for chemicals with limited data, and evaluate 
risks on populations at various spatial scales in the context of other stressors. Research projects 
under this plan center around conceptual models that will support the development and 
demonstration of frameworks for better assessing the risks of both non-bioaccumulative and 
bioaccumulative chemicals. 
Section 8 provides an approach for diagnosing the causes of biological impairment linking 
watersheds with receiving water bodies to support the TMDL process and other regulatory 
programs. The primary goals of this research are to provide: a framework for interpreting cause 
and effect relationships, single-stressor diagnostic methods and models to determine the primaiy 
source of biological impairment of aquatic ecosystems, and methods and models to allocate and 
forecast causality among multiple stressors for use in restoration and remediation actions. The 
principal components of this research area align with the primary goals and will provide: the 
scientific foundation and information management scheme for the 303d listing process, and a 
classification fi-amework for surface waters, watersheds, and regions; diagnostic methods to 
distinguish among major classes of single and multiple aquatic stressors; and diagnostic tools for 
forecasting approaches. Specific research projects will be conducted to establish the conceptual 
framework to guide implementation of diagnostics, provide case studies to develop and test 
methods for both single and multiple stressors, and to establish the structure for a decision 
support system. 
Over the next six years (2002-2008) the proposed research, integrated across areas, will provide 
increasingly sophisticated tools to help resources managers assess ecological conditions, 
diagnose impairment and causes of impairment, and forecast the effects of changes in stressor 
levels. As short-tom to inteimediate-term research on aquatic stressors is completed, this 
implementation plan will change, so that new or continued research will provide the tools 
necessary to identify, assess, and manage aquatic stressors and contaminated sediments to meet 
goals under the Government Performance and Results Act. 
XVI 
