The elevation of the Madera viticultural area increases from west to east, from above sea level along the San Joaquin River on the west and after gently sloping for to on the extreme eastern boundary in Fresno County. Rainfall throughout the viticultural area is sparse, from per year, and averaging per year in the Madera-Fresno area. This differentiates the viticultural area from the west where rainfall averages in the Los Banos-Mendota-Firebaugh areas, and from the east where rainfall is higher averaging per year in the Friant-Auberry area. In terms of degree days, Madera averages 4259 degree days according to records kept by the Madera Irrigation District. This contrasts with warmer areas both to the north where Merced averages 4430 degree days, and to the south where Fresno averages 4680 degree days. The growing season in the Madera viticultural area averages between 260 and 270 days, with periodic freezing temperatures during the winter which trigger vine dormancy. To the east in the Fnant-Auberry area, the growing season is 220 days, while to the west in the Los Banos-Mendota-Firebaugh area, the growing season averages 285 or more days per year. Thus, the Madera viticultural area is distinguished from surrounding areas by the length of the growing season.
Climate Due to the characteristics hot and dry climate of this area, grape growers rely solely on irrigation water from the Sierra Nevada Mountains to the east. Because of the climate, and the availability of irrigation water, grape yield per acre in the proposed area is much larger than in the coastal regions of California.
Soil The petitioner states that the soils are composed of three major alluvial soil associations; San Joaquin-Madera, Cometa-Whitney and Hanford-Tujunga. These soil associations are all derived primarily from granitic sediments and are moderate to well-drained. The petition stated that the viticultural area contains well drained, non-alkali soils well suited to the cultivation of grapes while the western part of the county, the soils change to a highly alkali type unsuited for grape growing. During the hearing, Steven Ficklin, representing the petitioner, stated that a period of several years of soil treatment would be needed to leach the alkali (hgh sodium) content of this soil to below the rootline of grapes, arid that if the soils were not leached, the alkali content would damage grape vines. Several respondents representing grape growers in western Madera County objected to the exclusion of the western part of the county based on soil. Mr. Robert Smith, a Madera vineyard owner and manager of vineyards in western Madera County, testified that sodium could be leached out of alkaline soils through the application of large amounts of water, such as by irrigation during farming. He also stated this process could be hastened by the application of sulfuric acid or gypsum. Smith testified that the soils in the two vineyards which he manages in western Madera County do not have high sodium levels. Seven other persons testified during the public hearing that they have grown grapes in the western part of Madera County, some for as long as 25 years. Morgan Johnson, a Madera County grape grower, testified that some of the soil in the western part of the county is neutral and not alkaline. He also testified that drip irrigation could substantially reduce the alkaline content of some soils m one year's time. In post hearing comments, one additional person commented that he is growing grapes in western Madera County. The Bisceglia Brothers Wine Company in Madera also stated that they purchase grapes from western Madera County and that they favor extending the viticultural area into the western part of the county. ATF examined all the evidence presented in written comments, in oral testimony received at the public hearing, and in post-hearing submissions. On the basis of all available evidence, the western boundary of the viticultural area is established as the San Joaquin River, and all of the western portion of Madera County are included. Evidence shows that grapes are grown throughout central and western Madera County, although plantings in the western portion of the county tend to be newer. Also, soil differences exist throughout western and central Madera County, based on a soil map submitted by Steven Ficklin during the public hearing. This map shows large areas of free (non alkaline) soil within the western portion of Madera County; these areas are centered along the north–south boundary, and to the north along the Chowchilla River. The same map also shows substantial areas of intermittent free and saline soils in the western part of the county along the San Joaquin River. Because of these soil types found within western Madera County, it is not possible to characterize all of the soil within this area as highly alkaline. By testimony given during the hearing, vineyards exist in free soils in this area which are identical to soils found in the central part of the county. Therefore, in order to use soils as a basis for the western boundary of the Madera viticultural area, ATF would have to draw very exact boundaries based on soil types. This is impossible due to the lack of any distinguishing geographical features appearing on
U.S.G.S. maps covering western Madera County. ATF determined that a geographical feature other than soils should be used to define the western boundary of the viticultural area. This geographical feature is the San Joaquin River, which divides Madera County from Fresno County, and distinguishes the viticultural area from the area to the west which is both drier and has a longer growing season. ==Name==