Dairy Herd Size Concentrations in the Central Valley, California

California is the nation's leading dairy state. Over the past 30 years the number of milk cows in the state has doubled (to more than 1.8 million), the number of dairies has dropped by half (to approximately 2,000), and the number of cows per dairy has tripled (to over 900). This increase in the amount and concentration of animals and their waste contributes to air and water pollution, especially in the San Joaquin Valley, which experiences some of the most polluted air in the nation and fails to meet the federal Clean Air Act’s National Ambient Air Quality Standards for ozone and particulate matter. The San Joaquin Valley Dairy Manure Collaborative was formed to initiate a coordinated strategy to address dairy waste issues and to fully use dairy manure as a resource. To support the collaborative, the Central Valley Dairy GIS Project identifies areas with the highest densities of dairy cows in hopes that more efficient management and treatment of dairy manure will improve the quality of soil, air and water; create jobs; stabilize rural economies; and provide a source of fertilizer and renewable energy.

Courtesy of the U.S. Environmental Protection Agency Region 9.