Spreck Rosekrans is an Economic Analyst at EDF.

We often hear that the Delta provides drinking water to 23 million Californians. The statement is true. And since our population is about 38 million people, it sounds like most of our water.

But the statement is misleading. First of all, about one third of all the drinking water in urban southern California and the Bay Area moves through the Delta – certainly not all of it. So, at a minimum one should probably say “the Delta provides some of the drinking water to 23 million Californians.

We should also note that the State Water Project, which moves most of these urban supplies, was developed primarily for our growing cities long after most water rights in California were reserved for agriculture. Even at their maximum level of about 6 million acre-feet, Delta exports account for only about 15% of the 40 million acre-feet we use statewide in our cities and on our farms.

Don’t get me wrong. Delta exports are a very important part the overall water supply in California. But they are at most only 15% of the statewide total and, were the remainder more uniformly distributed, the urgency of maintaining those exports would be greatly diminished.