Overarching Principles

This module concludes by reviewing some of the important points discussed above in the form of some overarching principles to follow when choosing appropriate models for watershed assessment.

1. Have a clear statement of project objectives and verify the need for modeling.

Ask yourself: How can a model help address the questions and problems relevant to decisions? How can a model be used to link stressors or management actions to quantitative measures (endpoints) of waterbody condition? Is modeling appropriate for examination of the stressors of concern in this situation?

Some of the types of problems for which modeling could be useful include:

• Quantifying loads from nonpoint sources
• Estimating load reductions needed to meet a water quality standard
• Establishing a total maximum daily load (TMDL)
• Distinguishing between levels of effectiveness of different management strategies
• Determining if management criteria can be met by a proposed strategy.

Remember that, where practically and economically feasible, real data are always preferable to model predictions as a basis for decisions.