​The nonpoint source and stormwater component of a WRE is intended to inform the land use planning process by evaluating receiving waters and land areas suitable for appropriate stormwater management treatment. It is also intended to ensure that the land use planning and management process is used as an effective nonpoint source pollution management instrument. By serving in this capacity, the WRE process will also ensure that nonpoint source pollution from development does not, in conjunction with point source pollution, exceed the assimilative capacity of receiving waters.

With respect to its broad role and purpose, a comprehensive plan should address the full range of options that might be employed to protect water resources. Options should be assessed to quantitatively evaluate competing goals and alternatives in an effort to shape the direction of the WRE and the comprehensive plan.

To illustrate, assume that an assessment reveals that a net increase in nonpoint source pollution resulting from estimated future development outside of a PFA under current trends or a reasonably foreseeable alternative development scenario will consume 50% of the assimilative capacity estimated to exist in a watershed at the time a comprehensive plan is being developed. That would leave 50% of the total capacity to support future development within a PFA in the watershed. However, 90% of the capacity will be needed to support 100% of the development intended for the PFA. At the simplest level, the Plan should either reduce the amount of development intended within the PFA, or reduce the potential for development outside of the PFA to a level likely to require only 10% of the assimilative capacity remaining in the watershed at the time of Plan development.

Since two goals of the comprehensive plan are to concentrate development in PFAs and conserve rural resource land outside of PFAs, only the second alternative – reduce the potential for development outside of a PFAs– is consistent with those goals. That alternative can be accomplished by: down zoning; initiating a transfer of development rights (TDR) program, which sends development rights from parcels outside of PFAs to parcels inside PFAs; by accelerating and intensifying an existing land preservation program; or through some combination of the preceding and a variety of other tools.

Additional implementation responses, such as those enumerated in subsection VI.F., Linking Stormwater Management to the Land Use Implementation Elements, can be employed to reduce the pollutant load or impervious cover required to accommodate a given amount of development outside of the PFA. Techniques under Implementation Policies in the Wastewater Treatment section on page 31 of this guidance document can be employed to support more development either within or outside of PFAs, or both. Advanced stormwater management and on-site sewage disposal techniques will reduce the pollution that must be assimilated by the receiving water body. Similarly, better protection of Sensitive Areas and aggressive use of environmentally sensitive and low impact development site design will also reduce impervious cover impacts. (Note that these impacts are beyond the scope of the analysis tools referenced in this Guidance.)

Whatever implementation is prescribed by a comprehensive plan, it is important to bear in mind that the WRE and the associated land use management programs used to direct development to appropriate areas will play a major role in determining a jurisdiction's ability to realize its plans for future development within a PFA. If the amount and location of development is not considered in this context, it will inefficiently consume the assimilative capacity needed to support future development.