Carbon Footprint of Water in California

Sokolow et al.¹ present a thought-provoking approach for considering the health impacts of water conservation in Southern California. They also, though, present errors about the energy use and carbon footprint of California’s State Water Project (SWP), which is owned and operated by the California Department of Water Resources (DWR).

For example, Sokolow et al. state that transport of water via the SWP “alone is 2% to 3% of the state’s total energy.”^1(p942) This statement is false. In fact, after accounting for its self-generation of clean hydroelectricity, the SWP’s energy demand is well below 1% of the total energy usage in the state. Furthermore, the authors state that the SWP’s energy usage results in “roughly 4 million tons of GHG [greenhouse gas] emissions per year.”^1(p942) This statement, too, is false. In fact, in 2014—the most recent year for which an independently verified inventory is available—the SWP’s carbon footprint was less than 500 000 metric tons. For context, California’s carbon footprint in the same year was 442 million metric tons, so the SWP’s emissions represented only 0.1% of the state’s total GHG emissions that year.

DWR was honored in 2015 and 2016 with the highest national honor for climate leadership, specifically for Excellence in GHG Management and Organizational Leadership, respectively. As of 2014, the Department has reduced its GHG emissions 30% below their 1990 levels, well ahead of the mandate established by Assembly Bill 32, California’s Global Warming Solutions Act. At the same time, DWR is well on its way to meeting the state’s new standard set by Senate Bill 32—signed by Governor Brown in September 2016—that requires a statewide reduction in GHG emissions of 40% below 1990 levels by 2030.

While the energy and carbon impacts of water management are important, it is more important to get basic facts and figures correct, so as to not exaggerate those impacts, and to ensure that related analyses are also correct.