John Bidwell learned of Marshall’s gold discovery at Coloma shortly after Marshall showed his gold samples to John Sutter. Sutter asked Bidwell to take a sample to San Francisco, which he did, probably in early February 1848, being the first to take the news to San Francisco. He must of kept pretty quiet about it though, because gold fever did not sweep through the city until March, when Sam Brannan ran through the streets shouting, “Gold! Gold in the American River!”
Brannan had good reason to ballyhoo the news—having learned about the discovery from Mormon workers at Sutter’s Mill, he promptly bought up every pick and shovel he could lay his hands on for his store at Sutter’s Fort.
Meanwhile, Bidwell was back at his farm on Butte Creek. He had stopped off at Coloma and staked a claim there, but he never mentions going back to the American River to mine. Instead, he searched for gold on the Feather River.
“On my return to Chico I stopped one night at Hamilton, on the west branch of the Feather River. On trying some of the sand in the river, I found light particles of gold, and reckoned that if light gold could be found that far down the river, the heavier particles would remain near the hills.” In another account he wrote:
“While my horse was off feeding, I took a tin up and went down to the river, washed the sands as well as I could, and every cupful took out small particles of gold.” He had found a river every bit as rich as the American.
He doesn’t give a date for this, but it was probably sometime in March of 1848. He went back to his cabin on Butte Creek and began organizing an expedition to properly mine for gold on the Feather River. By May he was well-established at a place soon to be known as Bidwell’s Bar.