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12.7 Selection of Best Management Practices 451
A major problem with this approach is that many relationships pertaining to BMP
selections are nonlinear. Qualitative factors are also difficult to incorporate in the
process, especially in the form of linear functions of the decision variables. Nonlinear
optimization, while accounting for the nonlinear dependence of various factors, is math-
ematically complex. It also tends to suffer from the same types of drawbacks as linear
programming because it is not effective for problems that include qualitative factors.

12.7.2.5 Determination of Appropriate Decision Analysis Approaches Matrix comparison
and decision factor analysis approaches are typically best suited to BMP selection. Such
approaches rely on the analytical tools available to analyze the system and on the best pro-
fessional judgment of those assessing the alternatives. Given specific problems that can be
quantified, optimization could be tried. Most BMP selection projects involving urban
runoff, however, would be too complex. If the problems being addressed are simple, then
the holistic or cost/benefit ratio techniques can be utilized. These simple, qualitative ap-
proaches can also be implemented as first approximations for plan assessments whose final
results must be made using more complex approaches. In summary, an appropriate deci-
sion analysis method or methods must be selected that reflect:

1. The complexity of the problems and the plans to address them
2. The data needs of each method and the ability to obtain the required data
3. The financial and personnel resources available to conduct the assessment.

The selection of BMPs to control urban runoff pollution is difficult and can best be
performed by undertaking a systematic assessment process, aided by the use of analytical
tools and the selection of appropriate design conditions and decision factors. Because of
the qualitative nature of some inputs to the decision, subjective comparisons among the al-
ternative plans typically are necessary. The process outlined in this section is a guide for
decision making, but cannot account for all possible circumstances. Professional judgment
and care are needed in determining the methods for developing alternatives, the decision
factors to be employed, and the decision analysis method to utilize. Once these choices
have been made and the BMP plan has been selected, the urban runoff pollution prevention
and control plan can be developed in more detail so that it can be implemented.
The following case study provides an example of BMP selection approaches used by
the state of Maine for the development and implementation of a major runoff pollution pre-
vention and control plan.

CASE STUDY 12.2 MAINE DEPARTMENT OF ENVIRONMENTAL PROTECTION BMP SELECTION MATRIX
To address stormwater and NPS pollution control in areas of new development, the Maine
Department of Environmental Protection (ME DEP) has developed a method to select BMPs. The
method, which is presented in a state guidance document, is based on the following information:
• Development land use type and size
• Receiving-water type (e.g., estuary, wetland river, or stream)
• Watershed priority (either priority or nonpriority)
• Erosion and sediment control target or level to achieve
• Stormwater quality control target or level to achieve
• Erosion and sediment control options and treatment level codes
• Stormwater quality control options and treatment level codes.