BRAWLEY, Calif. — Three generations of Al Kalin’s family have worked their 2,000 acres of carrots and sugar beets, wheat and alfalfa for almost a century in the Imperial Valley, a scorching swath of Southern California desert that was unfit for farming until water from the Colorado River was diverted here in 1901.

But now Mr. Kalin and his brother enjoy a choice that their parents and grandparents never had. They can continue to farm all their land, or they can stop farming some of it and earn more than $500 an acre — more than the market value of a crop like alfalfa in a given year — simply by not using the water required to nourish those crops. Water saved is sent on to thirsty cities and suburbs to the west: San Diego, Los Angeles and Palm Springs.

With water increasingly scarce in the West, some other communities are allowing farmers to sell their allotment of it for whatever price they can find, in some cases thousands of dollars for the amount it takes to grow an acre of a crop. But this comes with a hitch. Working farms provide jobs and income to their many suppliers. There are 450 farmers in the Imperial Valley, but half the jobs held by the 174,000 residents are tied to agriculture.

When land is idled, the communities around the farms can wither. Residents here point to the neighboring Palo Verde Valley, where farmers can sell more than a quarter of their water supply at much higher prices in a process they control. As a result, nearly a third of the agricultural land was not farmed this year; over time, businesses and workers have suffered.