Database of existing information 
,_i_, 
Conceptual models for nutrient load-endpoint responses 
I _ 
Classification scheme for receiving water bodies/endpoints 
I 
Standard or comparable methods for assessment endpoints 
I 
Nutrient load - water body response models 
Figure 5. Critical path for research on the development of nutrient response 
relationships for coastal receiving waters. 
Step 4. Develop Standard Methods and Procedures. 
This task will involve the determination of a set of standard measurement endpoints for the 
assessment endpoints. Comparability of measurements and data across Regions/Ecological 
Divisions, where possible, will maximize utility of data collection, research, and modeling 
efforts. A periodic review of these endpoints and procedures across the Ecological Divisions will 
ensure consistency and comparability and maintain focus on our core objectives. 
Step 5. Develop Nutrient Loading-Ecological Response Models. 
Nutrient Inputs/Loading 
In order to develop nutrient loading-response relationships for each of the three endpoints, it is 
necessary to estimate nutrient loadings. There are at least three ways that we may estimate 
loadings: 1) estimate using watershed models augmented with point source, atmospheric, and 
oceanic inputs [i.e., USGS Spatial Referenced Regressions on Watersheds (SPARROW) model. 
Smith et al., 1997]; 2) use field-based water column concentration estimates during the 
biologically inactive portion of the annual cycle and then back calculate to loadings; and 3) use 
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