Course: Science Subtest I
Lesson: Earth's Resources
Topic: California's Fresh Water      Page 26 of 39  

Data for the Santa Clara Valley (a part of the Central Valley just south of the San Francisco Bay area) provides an example of the rapid increase in groundwater use: The first well was dug in the early 1850s; by 1865, there were about 500 artesian wells. In 1920, two-thirds of the valley was irrigated, and farmers were drilling 1,700 new wells each year. By 1930, water no longer rose to the surface on its own, as the water table was 80 feet below the ground surface. Industrial users of fresh water moved in, and by 1960 were using twice as much water as farmers. In 1964, the water table was 235 feet below ground level.

Subsidence in the Santa Clara Valley as of 1962. Source: Poland, J. F. and Ireland, R. L, USGS