Napa Valley: The Lay of the Land

by Ronald Larson

The Napa Valley is located an hour northeast of San Francisco. Calistoga, the northernmost town in the valley, is about 75 miles from the city. Immediately to the west of Napa Valley is the Sonoma Valley (part of Sonoma county and also a major wine producing area). To the north is the " Lake Country " which is in Lake County and includes Clear Lake, the largest natural lake in California, and possibly the oldest lake in North America. To the east is Sacramento and the San Joaquin Valley.

Napa Valley is just one of several valleys in Napa County, but is the largest and most well-known. Although Napa County is more than 750 square miles in size, the Napa Valley itself is only about 30 miles long and from one to five miles wide. Running from the northwest to the southeast, its southern end opens into San Pablo Bay, part of the San Francisco Bay system. San Pablo Bay is home to a large area of wetlands which are major breeding grounds for the bay's aquatic animal life and an important stop for birds on the Pacific Flyway. The valley's grape vines begin just above the high tide line where the wetlands give way to hills.

The valley is bordered on the east by the Vaca Mountains and on the west by the Mayacamas range which extends north and west into Sonoma, Lake, and Mendocino Counties . The name "Mayacamas " is reportedly derived from either the Yuki, a Native American tribe which lived on the western slopes of the mountains or is the name of a Yukian Wappo village, Maiya'kma, which was most likely located one mile south of Calistoga. The Vaca Mountains are dryer and more arid that the Mayacamas Mountains because the Mayacamas draw the rain out of the winter storms before they make it to the eastern side of the valley. As a result, the vegetation in the two mountain ranges is different. Conifers with ferns at the higher, wetter elevations charactorize the Mayacamas Range whereas in the drier Vaca Mountains, Oak trees and grasses predominate.

The southern end of the valley is cooler during the summer growing season due to its proximity to San Pablo Bay . The northern end, farther from the ocean and encircled on three sides by mountains, is often warmer by an average of 10 degrees. The valley floor also rises slightly from sea level at the southern end, to 362 feet in Calistoga, at its northern end. The soil in the southern part of the valley is mainly sedimentary clay and sand laid down by expansions and contractions of San Pablo Bay over the eons, while the soils at the northern end of the valley are largely ash and lava left by ancient volcanic eruptions.

The valley narrows as one travels south to north; from five miles at its widest point near Napa to only a mile wide at Calistoga. The height of the surrounding mountains also increases, rising from flat estuaries and gently rolling hills in the south to the 2,677 foot Mt. Veeder northwest of Yountville in the Mayacamas range and the 2,663 foot Atlas Peak due east of Yountville in the Vaca Range.

There are several hills prominent in the middle of the valley just north of Yountville. These are the remnants of volcanic eruptions that occurred about two million years ago (more or less). These eruptions left a series of ash and lava deposits called the Sonoma Volcanics over much of Sonoma and Napa Counties, especially in the Mayacamas Range .

North of St. Helena the valley narrows rapidly, the sides grow steeper and the valley floor becomes more rugged. The soils are coarser in this part of the valley and rocky in so many places that grape growers refer to their vineyards as "horizontal hillsides."

At the northern end of Napa Valley is Mount St. Helena (which is technically in Sonoma County), the Bay Area's highest peak at 4,343 feet. Known to Native Americans as kana'mota or "human mountain," it is one of the premier hiking destinations in the San Francisco Bay area. On a clear day from the summit one can see the skyscrapers in San Francisco and the snow-covered Sierra Nevada Mountains 150 miles to the east. It is said that on the best of days you can see Mt. Lassen and Mt. Shasta, the latter 192 miles to the north. The highest point in Napa County itself is Sugarloaf Mountain, northeast of Calistoga, at 2,988 feet. All these mountains are tall enough to be covered with snow in winter.

Calistoga, at the foot of Mount St. Helena, has numerous geothermal vents and hot springs. To the northwest of the town, is an area of geyser activity known, not surprisingly, as "The Geysers." They are currently used as a source of thermal energy. The hot springs and geothermal vents located throughout the valley is evidence, not only of the valley's volcanic past but indicates there is residual volcanic activity.

Another important feature of the valley that emerges from the foot of Mt. St. Helena is the Napa River, a 40-mile long river that bisects (and drains) the entire valley. The Napa River, is one of only four navigable rivers in California and one of the last three surviving free-flowing rivers. It is also one of the largest Central Coast Range Rivers with 47 tributaries that total 250 miles of streams.

The Napa River forms just south of Mt. St. Helena and flows south, entering the Napa Valley north of Calistoga, flowing through the town and passing to the east of St. Helena and Yountville bisecting Napa on its way to San Pablo Bay. The head of navigation is Napa, seventeen miles from the bay. Beyond this point navigation by commercial shipping is not possible as the river dwindles slowly until it is little more than a creek at Calistoga.

From Trancas St. in Napa to Vallejo, the river is a tidal estuary. The flow of the river changes depending on the tides. In summer when the flow of fresh water from the mountains is at its lowest, the salinity in Napa may be 10%, while during the winter rains the river is entirely freshwater.

The Napa River is not only a major source of freshwater for San Francisco Bay, it also provides habitat for a wide variety of wildlife. Although the Coho and Silver salmon are extinct and the Steelhead population has been reduced from more than 6000 to several hundred, Chinook salmon still spawn in the river. One of the major reasons for the decline in the salmon population is that 6,500 acres of wetlands in the valley have been drained and filled in since settlement. In 1987, the Napa River was listed as "impaired" by the California State Water Quality Control Board. Nevertheless, the river still has active recreational fishing. Species include bluegill and black bass in the upper part of the river and striped bass, sturgeon and many non-game species in the lower river.

There are also many bird species dependent on the river. They include mallard ducks, wood ducks, green-winged teals, herons, egrets, kingfishers, as well as the endangered Clapper Rail. Many mammals also rely on the river for their habitat. These include the mink muskrat, raccoons, deer, gray foxes, and bobcats. A local group, "Friends of the Napa River," (www.friendsofthenapariver.org) was formed to preserve the health of the river and is working to restore it.

The river, unfortunately, is prone to flooding from November through April from St. Helena to Napa. The Napa River has flooded significantly at least 22 times since 1865. The most serious recent floods occurred in 2005, 1997, 1995, and 1986. In 1986, 250 homes were destroyed, 5,000 people were evacuated, and three people died.

Voters recently approved a bond issue to restore the river to a more natural state which would hopefully minimize flooding of populated areas. Called the "living river" design, the plan includes reconnecting the river to its original flood plain, keeping the natural width of the river, allowing it to meander as much as possible, preserving natural channel features like mud flats, shallows and sandbars, and supporting the native flora and fauna along the river. Construction of the plan is now underway but will take years to complete.

The Napa Valley's climate and soil not only make it a place where a wide variety of crops such as apples, prunes, and olives thrive, but is also optimal for the growing of wine grapes. With a coastal climate that results in warm days and cool nights and a soil that is deep but not too rich, the Napa Valley yields grapes that are especially well-suited for wine production.

The varied soils, along with a complex topography, create what are called micro-climates; small, specific climates that vary from each other, perhaps from one vineyard to another. The differing micro-climates mean that different vineyards produce grapes that are unique from the others, which gives the wine produced from each vineyard its own taste and character.

Of course, Napa Valley 's claim to fame is not the natural beauty of the area or its combination of rural living near one of the great American cities, it is its wine industry and the associated tourism. The Napa Valley is home to nearly 400 wineries, ranging in size from small family-owned operations to large publicly held companies. Because of its rich volcanic soil and ideal climate for viticulture, the Napa Valley produces some of the world's finest wine. It is this industry, along with scenic vineyards, elegant accommodations, and gourmet dining that has made Napa County's wine country, second only to Disneyland in popularity as a vacation destination in California.

What visitors soon realize when they arrive in the Napa Valley, whether for a wedding, a romantic getaway, or to have the "winery" experience, is that there is more to see and do than they imagined. The Napa Valley boasts world-class restaurants and cuisine, great wine, swank boutiques, relaxing spas, and a wealth of outdoor activities including hiking, horseback riding, kayaking, bike tours, and hot air ballooning.

Photos courtesy of Nick Elias. Nick Elias lives in Lake County, California and is the founder of Water Pear Press. To view more of his imagery and to order decorative enlargements, visit www.waterpear.com.