SPRING is about to break forth, if it hasn't already. But the recent dry, sunny weather obscures the New Year rainstorms that flooded many parts of Northern California, especially the fertile Central Valley.

Most city dwellers are oblivious to the aftereffects of those January floods on many rural communities.

As I got to thinking about flood control and agricultural abundance and the confluence of natural and human-made wonders, I grew curious about origins of the dozens of earthen levees in the Sacramento-San Joaquin Delta. The Delta's waterways have become a huge fresh-water reservoir, an integral part of state and federal systems for agricultural irrigation, flood control and shipment of drinking water to Southern California. And the islands have become extraordinarily fertile farmlands.

According to historians and water experts, the area that makes up the Delta, an easy one-hour drive from the urban East Bay, was tidal marshland 150 years ago.

After California became a state, the great floods of 1860 prompted the state to attempt flood control through the giveaway sales of 2 million acres of "swamp and overflowed lands" to individuals who promised to

"reclaim" the land. In the Delta, that meant dredging channels and building levees in an area that already had many islands. The idea was to make the land suitable for agriculture and the channels helpful in absorbing flood waters.

Landowners who launched reclamation projects turned to Chinese laborers to do work that was, in the words of one historian, "extremely unpleasant."

Thousands of Chinese immigrants had come to California first to mine gold during the Gold Rush, then to build the western half of the transcontinental railroad system. Discrimination discouraged the Chinese miners, and completion of the railroad made Chinese laborers readily available to build up the Delta levee system from the 1860s onward.

George Basye, past president of the California Historical Society and an attorney for the California Central Valley Flood Control Association, said Chinese laborers were hired to build the levees because "they were available and cheap."

Maurice Roos, chief hydrologist of the state Department of Water Resources, said, "The Chinese were a good labor force. The pay and conditions (of building the levees) weren't things others wanted to take."

In her study, "This Bittersweet Soil: The Chinese in California Agriculture, 1860-1910," historian Sucheng Chan wrote, "Chinese tenant farmers and farm laborers were intimately involved in every phase of the Delta's land reclamation and farm-making. In fact, it can be argued that without them the Delta would have taken decades longer to develop into one of the richest agricultural areas in the world."

Chan said landowners like Reuben Kercheval, P.J. van Loben Sels and George D. Roberts hired Chinese laborers to build up the Delta levee system, work that ultimately brought the landowners huge returns on their investment.

Roberts, who was president of the Tide Land Reclamation Co., bought swampland for $1 to $4 per acre and spent $6 to $12 per acre reclaiming it, according to Chan. He sold the partially or wholly reclaimed land for $20 to $100 per acre.

"None of the work would have been done, however, had Chinese laborers not been available," Chan wrote.

"When asked whether he (Roberts) could have obtained white men to do the work, he said, "I do not think we could get the white men to do the work. It is a class of work that white men do not like . . . Very few of them come here to do cheap labor . . . We could not afford to pay three or four dollars a day to white men to do our work.' "

William Wong is an independent journalist and Examiner columnist.<