RIVERSIDE, Calif. -

Plans to turn a 19,000-acre swath of southwest Riverside County into a viticultural Valhalla -- despite a variety of challenges stemming from pollution, noise and traffic -- will be on the Board of Supervisors' agenda for consideration next week.

The Temecula Valley Wine Country Plan, in development since 2008 and approved by the county's Planning Commission last December, will require revisions to the county general plan, as well as changes to zoning designations and the approval of an environmental impact report that points to unavoidable problems as the build-out occurs.

The board will hear a lengthy presentation and testimony regarding the wine country plan during its afternoon session Tuesday.

``The purpose of the project is to provide a blueprint for growth to ensure that future development activities will enhance, not impede, the quality of life for existing and future residents, while providing opportunities for continued development and expansion of winery and equestrian operations within this part of the county,'' according to a county Transportation & Land Management Agency statement submitted as part of the presentation.

Under the plan, the Temecula Valley Wine Country would be defined as encompassing an unincorporated area three miles north of the San Diego County line, just east of Temecula, south of Lake Skinner and Northwest of Vail Lake, according to TLMA documents.

The area is currently home to 42 vintners, or wine growers. Supervisor Jeff Stone, whose third district covers the entire southwest county region, envisions 120 wineries eventually operating there.

Preparing the area for expansion will require new infrastructure, more government services and accommodations for existing residents and businesses -- all of which pose challenges, though most of them can be mitigated, according to the environmental impact report prepared for the board.

The TLMA is recommending that the board tentatively approve the 711-page EIR, which identifies the following ``significant'' impacts arising from the project:
   -- a 25 percent reduction in the amount of prime farmland otherwise available for cultivation;
   -- an increase in particulate air pollution because of vehicle traffic, industrial equipment, grading, excavation and other activity;
   -- an increase in greenhouse gas emissions that exceed the South Coast Air Quality Management District's ``draft mass emission thresholds'';
   -- an increase in noise during the construction phase and afterward, as large-scale events, including weddings and wine tastings, occur;
   -- greater demands on fire protection services, which are already spread thin throughout the area; and
   -- higher traffic volume and more roadway congestion from tourists and businesses.

Planning officials proposed a number of mitigation measures to offset the impacts, though none of them would provide a 100-percent fix, and some efforts would have to be undertaken on an ad hoc basis, documents showed.

``It should be noted that while the proposed project represents an increase in new development compared to existing conditions in wine country, it is considerably less dense than currently allowed in the county's general plan policies,'' the TLMA stated.

As part of the wine country plan, the board will have to approve replacing the Citrus Vineyard Policy Area Design and the Southwest Area plans, as well as implementing the following new zoning classifications: Wine Country-Winery; Wine Country-Residential; Wine Country-Equestrian and Wine Country-Existing.

Each designation specifies the character of a subdivision. One key change would be mandating that the minimum size of a vintner be 20 acres, instead of 10, and that at least half of all wine distributed be made on site.

Plan advocates tout the economic advantages of expanding the wine country, with more vintners, inns, stores, equestrian arenas and other commercial enterprises contributing to increased employment and a higher standard of living.

Critics dislike the added stress on local resources and the overall size and scope of the project, which would evolve over several decades.