Land subsidence is not a new topic of discussion in California. It has been a part of California’s agricultural history ever since farmers introduced large-scale wells to pump groundwater from the Central Valley’s aquifers. In a very interesting photo, USGS Scientist Dr. Joseph F. Poland stood next to a telephone pole near Mendota, CA in 1977 to show the effects of land subsidence on the valley floor. As you can see in the linked picture, he put signs on the telephone pole noting where the land would have been in 1925, 1955, and 1977. Dr. Poland’s analysis determined that the valley floor in that area fell approximately 8.93 meters (over 29 feet!) between 1925 and 1977 when he took that picture. Unfortunately, after a century of pumping in the Central Valley, little has yet changed to make the process more sustainable. Continue reading →