Topography The geography of the area sets it apart from surrounding areas in several respects. "Redwood Valley" is clearly defined by the ridges of the coastal mountain range that surrounds it and that the Valley floor slopes gently up in elevation from around above sea level. The mountain ridges rise steeply from the valley floor to over elevation. Most of the grapes are grown at an elevation between above sea level. At the south end of the valley the foothills close in from the east and west to form a narrowed throat through which the
Russian River flows south. This narrowing is also where
Highway 20 crosses the valley and the river to intersect with
Highway 101. This combination of
landforms provides a natural set of boundaries for the viticultural area. These features combine in several ways to produce growing conditions which distinguish the area from surrounding areas. The soils, as well as the micro-, meso-, and macro-climates are all factors that distinguish the viticultural area from surrounding areas. The petitioner states that, "(s)ince November of 1987, Light Vineyard of Redwood Valley (Latitude 39 degrees 18.32', Longitude 123 degrees 12.46', elevation 800') has maintained a U.S. Weather Bureau standard weather station including the following instruments: maximum/minimum thermometer, Belfort Recording Hygrothermograph, Belfort Recording Pyranograph, Totalizing Anemometer, Evaporation Pan, and Rain Gauge. Readings are taken daily, and data are transmitted monthly to the California Irrigation Management Information Service in Sacramento." Records from this station show that, in the most recent eight year period, the "Redwood Valley" received 22% more rainfall than the Ukiah Valley. The petitioner provided a table comparing the monthly totals for rainfall in "Redwood Valley" and Ukiah, for the eight year period for which they have maintained records. The table and charts were prepared from data gathered from the Light Vineyard Weather station which meets U.S. Weather Bureau standards. According to these records, the average total monthly rainfall in Ukiah Valley was 32.48 inches during the period of July through June compared to an average total of 39.62 inches for "Redwood Valley" during the same period. The petitioner also provided a graph comparing the annual rainfall values for "Redwood Valley" and Ukiah Valley averaged over a six year period. The graph indicates that the precipitation values for "Redwood Valley" were consistently higher than those for Ukiah Valley over the six year period measured. "Redwood Valley's" temperatures are several degrees lower in daily lows than Ukiah Valley. The petitioner states that, "(t)his accounts for the lower growing degree day totals in Redwood Valley and its placement in Region II. So, although Redwood Valley may reach daily high temperatures similar to the Ukiah area, because of cooler nights there remains a longer morning cool period." The petitioner also provided achart comparing monthly average temperatures for the two areas averaged over a six year period. This chart supports the petitioner's contentions regarding average maximum and minimum temperatures.
Soils While all of the specific soil series that are found in "Redwood Valley" also exist in the surrounding areas, the proportions of the soils in "Redwood Valley" distinguish it from the surrounding areas.
The Wine Regions of America, a book written by John J. Baxevanis in 1992, gives the following description of the Redwood Valley area. "Redwood Valley, the northernmost of the string of Russian River Valleys, lies (eight) miles north of Ukiah and Lake Mendocino on a series of higher terraces. Representing the birthplace of Mendocino winemaking, it is the home of some of the county's largest wineries. With more than 40 percent of the county's acreage, it is the most important of all the producing regions in the two county region [Lake and Mendocino]. A region II area, it produces above-average quality Zinfandel, Cabernet Sauvignon, Chardonnay, Petite Sirah, and Sauvignon Blanc. One of its elements of celebrity is the considerable quantity of Manzanita soil." The petitioner was unable to ascertain the origin of the term "Manzanita soil." However, he states that, "Redwood Valley does contain the largest deposit of the famous Redvine soil in the region and perhaps it is this to which Baxevanis refers." The soils in the viticultural area have several unique features as determined by the
U.S.D.A. Soil Conservation Service (SCS). The
1991 Soil Survey of Mendocino County, Eastern Part, and Trinity County, Southwestern Part, California, was used extensively by the petitioner to determine the identity and areas of soils for comparison. Whereas all of the specific soil series that are found in "Redwood Valley" occur in the surrounding area, it is the proportions in which they appear in "Redwood Valley" that are unique. "Redwood Valley" has by far the largest deposit of Redvine Series soil (#184-186 SCS Survey) in the area. Nearly one quarter of the viticultural area's plantable acreage is composed of soils of the Redvine Series. Potter Valley Viticultural Area to the east has no Redvine Series soils. The Calpella/Ukiah area to the south of "Redwood Valley" has a few small and isolated pockets of Redvine soils but their combined area amounts to less than 10% of the area covered by Redvine Series soils in "Redwood Valley." Another soil series that stands out, is the Pinole Gravelly Loam (#178-180 SCS Survey), which also occurs in the Potter Valley and Ukiah areas, but is a much smaller component of the area's overall composition. "Redwood Valley" has three times as much Pinole Gravelly Loam as either of these other two areas. This soil type makes up nearly a third of "Redwood Valley's" growing area. The Redvine and Pinole Gravelly Loam soil series comprise over half of the vineyard acreage of "Redwood Valley." The rest are an amalgam of six other types: Feliz, Pinnobie, Yokayo, Russian, Talmage, and Yokayo/Pinole/ Pinobie. These last six general types (plus traces of a few more types) evidence themselves in the neighboring areas in varying proportion, but all play a larger role elsewhere than they do in "Redwood Valley." The petitioner provided a table illustrating the proportions of soil types in the "Redwood Valley" area compared with the Ukiah/Calpella area. These figures were derived from SCS maps and soil descriptions, and were measured with a Compensating Polar Planimeter. The table indicates that, while "Redwood Valley" contains most of the same soil types as the Ukiah Valley, such soils are present in different quantities in the respective areas. ==See also==