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Designed to protect the Napa Valley growing region, the Ag Preserve was established in 1968 by the Napa County Board of Supervisors and the Napa County Planning Commission. The goal of the Napa County Agricultural Preserve was clearly spelled out in the first section of the ordinance:


“This district classification is intended to be applied in the fertile valley and foothill areas of Napa County from Napa to Calistoga in which agriculture is and should continue to be the predominant land use, where uses incompatible to agriculture should be precluded and where development of urban type uses would be detrimental to the continuance of agriculture and the maintenance of open spaces which are economic and aesthetic attributes and assets of the County of Napa.”


Napa Ag Preserve Timeline 

A chronology of events which shaped the level of land protection we enjoy today.


1966-1968: Ag Preserve Zoning District debated and enacted with the passage of Ordinance #274, establishing the minimum twenty-acre parcel size in the Ag Preserve

1968: Suit filed by Napa Valley United Farmers seeking an injunction to prevent Ordinance #274 from becoming effective.

1971: Superior Court upholds validity of Ordinance #274.

1973: Established minimum 40 acre limit in Ag Watershed areas.

1977: Board of Supervisors adopts Ordinance #610 increasing minimum parcel size in Ag Preserve Zone from 20 to 40 acres.

1979: Ordinance #541 adopted expanding the Ag Preserve in north Napa area by approximately 1,300 acres.

1980: Measure A, an initiative limiting the population growth in the unincorporated county areas to 1% per year passes.

1990: Measure J, an initiative that prohibits conversion of agricultural lands to non-agricultural uses without a vote of the people unless conversion meets with certain specified criteria passes; lawsuit immediately filed challenging validity of Measure J.

1994: County established 160-acre minimums in Ag Watershed & Open Space areas.

1995: California Supreme Court upholds validity of Measure J.

1999: Groundwater Ordinance passes, establishing protection & priority of groundwater for agriculture and requiring groundwater permits for new non-ag wells.

2008: Measure “P” passed by voters. It extends Measure “J” until 2058 and strengthens Measure “J” by including a policy that the minimum lot sizes for Agricultural Watershed & Open Space designated lands cannot be changed without a vote of the people.

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