The Oroville Spillway emergency in California may have one silver — or gold — lining: The debris kicked up by weeks of heavy rain and runoff is now flecked with gold, and amateur gold panners are enjoying quite the bonanza.

The "gold rush" is occurring along the Feather and Yuba rivers, which are fed by the Oroville Dam. Of course, would-be panners should take note: It's unlikely that panners will hit the jackpot and retire with steamer trunks full of gold bars; the average haul from panning the river lately is worth just $40 to $300, CBS5 reported.

The emergency spillway for the Oroville Dam in northern California was damaged by weeks of heavy rain in late February, after high water levels forced officials to use the relief spillway to divert some of the flow from the main dam. When the spillway was damaged and shut down, waters threatened to overtop the dam, the officials declared a state of emergency and evacuated 188,000 people. Ultimately, the damaged spillway was used to prevent a more catastrophic overtopping of the main dam; the spillway held up through the rest of the rainy season but sustained severe damage. [Photos: Dramatic Images of the Catastrophic Damage at Oroville Spillway]

Gold-rush history

The foothills of the Sierra Nevada mountains are famous for their gold. James W. Marshall first found gold at Sutter's Mill along the South Fork American River in 1848, according to Marshall Gold Discovery State Historic Park. Within a few years, hundreds of thousands of people had flocked to the Golden State in hopes of striking it rich. While some did, about half found too little gold to make up for the costs of mining it, Live Science previously reported.

Early miners could simply scoop gold out of the water, because the precious metal is much heavier than water and quickly settles to the bottoms of creeks or rivers. But as these easy pickings were exhausted, miners turned to more damaging and expensive methods of extracting gold for the region, such as blasting rock and pulling gold ore from the rock veins using cyanide and mercury, Live Science previously reported.

Though the first gold strike was at Sutter's Mill, over time, gold panners fanned out from this original spot to areas such as the Yuba and Feather rivers, which are farther north in the Sierra Nevada. Millions of tons of gold are likely still lurking in the rock in the Sierra Nevada, but much of it is either difficult to access or released in tiny flecks that are not economical to gather, according to a 1982 U.S. Geological Survey report.

The new gold rush likely is occurring because runoff carved huge chunks off the mountain below the spillway during the heavy rains. The state is rushing to repair the Oroville Spillway before the rainy season starts in November, The Sacramento Bee reported. Initially, officials from the state's Department of Water Resources planned to repair and replace the lower two-thirds of the spillway this year and fix the upper portion next year. But now, they're asking permission to make both repairs simultaneously. They hope the repairs will prevent problems that could occur if drought or other weather issues come up, The Sacramento Bee reported.

Originally published on Live Science.