ContentsPutah and Cache: Entering

Previous piece More like this

Next piece

Next chapter


Human Population within the Bioregion:
A Demographic Portrait

James C. Cramer

It is worth noting that the bioregion belongs, at least in part, to the humans who live in it. This section is about the human population that resides in the bioregion. It has a specific purpose: to present a demographic portrait of the local population, to describe the number of residents and some of their general characteristics. Such topics as the history, community organization, and hopes and aspirations of the residents are not discussed here.

Most of the population data presented here come from the decennial U.S. census. Because census units rarely coincide with ecological areas, it is difficult to identify accurately the population of a bioregion. For example, rivers often are used as boundaries dividing different census units, whereas they are in the center of ecological units such as bioregions. Thus many census units include some people who live within a bioregion and some people who live outside it. The solution adopted here is to utilize the smallest available census units (called census tracts), and to aggregate these units to approximate the bioregion as closely as possible. Inevitably the figures presented here include some people who do not live in the Putah Cache Bioregion and omit others who do.

In order to describe variation within the bioregion, I present data for four subregions: Upper Putah watershed, Lower Putah watershed, Upper Cache watershed, and Lower Cache watershed. Upper Putah includes the area from Winters northwestward to Lake Berryessa and Pope Valley. A majority of its population lives in Winters. Lower Putah watershed includes the area east of Winters; most of the Lower Putah population lives in Davis. Upper Cache includes all of Lake County. Its population is dispersed in rural areas and small towns, with no dominant city. Lower Cache includes the Capay Valley in Yolo County and the area downstream and east of Capay Valley, and most of its population lives in Woodland. To highlight the distinctive characteristics of the bioregion, I also present population data for the nearby 4-county Sacramento Metropolitan Statistical Area.

It is worthwhile to describe the population of the entire bioregion. Historically, the Putah-Cache bioregion has been sparsely populated, and the people have been predominantly rural and agrarian. Mining has been important in the upper watersheds. Only since 1950 have a few small towns grown into cities, with urban amenities and industries. The populations of the lower watersheds, especially in the emerging cities, have been modestly prosperous, while in the upper watersheds people have struggled economically but have not been poor. The bioregion is overwhelmingly of European origin, although there are large Hispanic minorities in some agricultural centers and several pockets of Asians and Native Americans. I suspect that differences between the four subregions were small earlier in this century and have grown larger since 1950, due to uneven urbanization.

History of population size

Because of changes in census boundaries, I have not attempted to estimate the population of the bioregion over time. Historical data are available for towns and counties, and I use these data to illustrate approximate trends. Table 1 shows historical population data for four towns: Davis in Lower Putah, Winters in Upper Putah, Woodland in Lower Cache, and Lakeport in Upper Cache. Davis, Winters, and Woodland dominate their subregions and fairly represent trends in the subregions. This is not true of non-dominant Lakeport, so in Table 1 I also show historical data for Lake County, which does represent fairly the trends in upper Cache watershed.

The period from 1880 to 1940 could be called the frontier agrarian epoch. Most urban places had populations less than 1000 through 1920. Only Woodland could truly be called a town, not a place; its population already exceeded 2000 in 1880, and exceeded 6000 in 1940. In all jurisdictions, population growth was very gradual, and setbacks were not uncommon (e.g., Winters 1910-1930, and Lake County 1890-1920), though changes in census boundaries or procedures may account for some of the change.

After 1940 the lower watersheds experienced rapid population growth, while the upper watersheds experienced slower but steady growth without setbacks. Growth was particularly startling in Davis, where the population more than doubled each decade from 1940 to 1970. During this period the small agricultural experiment station at Davis was transformed into a full campus of the University of California. Since 1970 growth of Davis has decelerated, so that by the most recent decade the population increased by "only" about 20 percent. Woodland also experienced remarkable growth, with increases over 40 percent each decade from 1940 to 1980; here too, growth has decelerated in recent decades. Part of the growth of Woodland is "spillover" from Davis, as UC employees tolerate a modest commute for the sake of cheaper housing.

Patterns of growth are quite different in the upper watersheds. In Upper Putah, Winters continued its historic gradual growth (with "spillover" from Davis accelerating growth since 1980) while further west the creation of Lake Berryessa depopulated the Berryessa Valley. In Upper Cache, population trends in Lakeport, which is somewhat remote, parallel those in Winters. However, Lake County as a whole had rapid population growth between 1960 to 1990, stimulated by tourism around Clear Lake; tourism increased due to transportation improvements and population and economic growth in nearby metropolitan areas (mainly Sacramento but also San Francisco Bay Area). Growth has slowed considerably since 1990. By 1999 Davis and Woodland have truly become small cities, with populations approaching or exceeding 50,000, while Winters and Lakeport remain small towns.

Social characteristics of the population

The most recent data on population characteristics in the bioregion are from the 1990 census and are nearly a decade old; the current situation may differ slightly from the following description. Several differences between subregions are apparent from Table 2. The Upper Putah population was about 7700 in 1990 whereas the other subregions each have populations of at least 40,000. Both upper watershed populations are largely rural, while both lower watershed populations are almost entirely urban. The proportion of people age 65 or older is unusually large in Upper Cache (23%) and unusually small in Lower Putah (under 6%). Both Upper and Lower Putah have large proportions of foreign-born residents relative to the Cache watersheds (and the Sacramento metropolitan region). These differences reflect unique features of the subregions. The qualities that attract tourists to Upper Cache also attract retirees, contributing to an older population. The major "industry" in the lower Putah watershed is the University of California at Davis, which attracts a large population of young students and foreign-born scholars. Winters, surrounded by labor-intensive orchards, is the site of a large agricultural labor camp, which accounts for the large foreign-born population.

These factors largely account for the subregional variations in race and ethnicity. The Upper Cache population is mostly of European descent, although a significant pocket of Native Americans is present. A large minority of people of Hispanic origin live in Upper Putah (Winters), many of whom presumably are or were agricultural workers. A relatively large Asian population live in Lower Putah (Davis), presumably drawn there by the University. Finally, we find in Lower Cache a large minority of native-born people of Hispanic origin; Woodland, in the center of an important agricultural area, has developed a substantial small-scale manufacturing sector that attracts the children and grandchildren of agricultural workers.

Family structure and household composition are similar across the four subregions, and similar to the broader Sacramento metropolitan area. Most individuals live in families, and most families comprise nuclear (i.e. single-family) households. Most families include both a husband and a wife. The most common non-traditional family structure is female-headed families; these are created both by divorce and by out-of-wedlock childbearing. The proportion of families headed by a female is lowest in the upper watersheds, higher in the more urban lower watersheds, and highest in Sacramento. The range of variation, however, is small-from 11 percent in upper Putah watershed to 17 percent in Sacramento

Perhaps the most revolutionary change in family structure and functions in this century is the increase in female employment outside the home. In most of the subregions, as in the Sacramento metropolitan area, about 60 percent of females age 16 and above were in the paid labor force in 1990. The glaring exception is Upper Cache, where "only" 40 percent of females were in the labor force. This subregion has an unusually high proportion of women age 65 or above, who are unlikely to be employed.

Relative to the other subregions and Sacramento, Upper Cache has a very high proportion of vacant housing units; only 72 percent were occupied on the census date, April 1. Many of those vacant housing units are for seasonal use only, i.e., by tourists (nearly 20%). Because of the seasonal population and the high proportion of elderly, this subregion also has an exceptionally high proportion of mobile homes (over 33%). Upper Putah also has a large proportion of mobile homes (over 13%), although far fewer than Upper Cache. The upper watersheds also have relatively high proportions of owner-occupied housing; this proportion is lower in urban areas, especially in Lower Putah, reflecting the large student population.

Economic characteristics of the population

In the United States, the most important determinants of social class standing, prosperity, and life chances are educational attainment, occupation, and income: see Table 3 for data on the bioregion.

The educational attainment of people in the Lower Putah is unusual due to the university; only 5 percent have not completed high school, and over 63 percent have completed college (many of whom have an advanced degree). In the other subregions, about 25 percent have not completed high school and fewer than 17 percent have completed college. This is low relative to the Sacramento metropolitan area, where more people have completed college than have not graduated from high school.

The unusual educational composition of Lower Putah population is reflected in its occupational distribution. Nearly a third of the employed persons in Lower Putah are in professional specialty occupations (e.g., teaching, research), whereas the "normal" proportion is less than one-sixth. There is a corresponding (relative) absence of precision production, service, and transportation workers and unskilled laborers.

The occupational structures of the remaining three subregions are reasonably similar, and none is dramatically different from the Sacramento metropolitan area. Upper Putah has large proportions of farmers while Upper Cache has large proportions of service workers, indicating the importance of agriculture in the former and tourism in the latter. A substantial light manufacturing industry in Lower Cache leads to a concentration of precision production workers, as does the large construction industry in Upper Cache.

Median household income is a crude measure of average prosperity in a region. By this measure, Upper Cache is poorer than the other subregions, with a median income (in 1989) of $21,800 compared to about $30,000 in the other subregions and nearly $33,000 in Sacramento. The crudeness of this measure, however, is demonstrated by Lower Putah, which has a low proportion of families below the poverty level (7.7%) but a high proportion of individuals living in poverty (25%). In Lower Putah most families are relatively prosperous, but many students live in non-family households and have very low income levels.

In Upper Cache, slightly more families are below poverty level than in other subregions, and slightly more individuals are in poverty (except relative to Lower Putah), but these poverty figures cannot account for the very low median household income. Upper Cache has a large proportion of persons living just above the poverty level (below 200 percent of poverty income). Undoubtedly this is due in part to the relatively large number of retired residents on fixed incomes, and also to the seasonality of the tourist industry. Lower Cache and Upper Putah have slightly higher median incomes and slightly lower poverty levels than the other subregions; they closely resemble Sacramento.


While similar in many respects, the populations of the four subregions are different. Because of the university, the population of Lower Putah is highly educated, predominantly young, and concentrated in professional specialty occupations; it has relatively prosperous families but many poor individuals. The population of Upper Cache is largely rural and has many elderly retired persons and many tourists (with a large seasonally-vacant housing stock); it is overwhelmingly of European origin, with relatively low levels of education and income (but not exceptional poverty). The population of Upper Putah also is largely rural, but it is heavily engaged in agriculture and has large minorities of foreign-born persons and persons of Hispanic origin; despite low levels of education, the population has only modest levels of poverty. The population of Lower Cache is predominantly urban and has an important concentration in light manufacturing; there is a large minority of persons of Hispanic origin (but native-born), and, as in Upper Putah, despite low levels of education there is only a modest level of poverty.

A technical note on the data

Upper Putah is defined as Napa County census tract 2018 (Berryessa) and Yolo County census tract 113 (Winters), which fall entirely within the bioregion. Areas of the bioregion left out of Upper Putah are the western side of Pope Valley in Napa County census tract 2017 (Angwin), and the area near Winters and south of Putah Creekin a Solano County census tract. These omitted areas are relatively small, and their population characteristics should be similar those of Upper Putah.

Lower Putah is defined as Yolo County census tracts 105.01 (all) and 105.05 (the non-urban part) and the city of Davis. These areas fall entirely within the bioregion. The area south of Putah Creek that is in Solano County is omitted; this area is relatively small, and its population should resemble the rural population of Lower Putah.

Upper Cache includes all of Lake County. This should be a very good approximation to the actual bioregion, although it does include a small population from the upper reaches of Putah watershed around Middletown.

Lower Cache watershed is defined as Yolo County census tracts 112.02 and 115 and the city of Woodland. The rural area around Woodland north of Cache Creek is omitted from the subregion; this area is in Yolo County census tract 114, which extends north to Knights Landing and Zamora. The omitted area is relatively small, and its population should resemble the rural population of Lower Cache.

Previous piece
Geology of Putah-Cache
More like this
Next piece
Next chapter