About 15 miles north of Fresno sits Millerton Lake, a reservoir created in the 1930s when the U.S. Bureau of Reclamation built Friant Dam on the San Joaquin River. The dam provides irrigation water for fields and groves in much of the San Joaquin Valley, but it wiped out the Chinook salmon migration that had existed on the river for tens of thousands of years.

It also threatened the rights of landowners to divert naturally flowing San Joaquin River water for their fields. Instead of losing their rights, though, farmers who had land near the river agreed to trade their water to the federal dam project in exchange for “substitute water,” delivered to them from the Sacramento River.