So many cattle were drowned and washed out to sea that it changed California from a Cattle State to a Farming state then in 1862

If you read the accounts of the northern California cattle ranches being completely wiped out you understand just how devastating it was. 

Here is an eyewitness account by John Carr from 1861: 

begin quote from:

https://en.wikipedia.org/wiki/Great_Flood_of_1862#Northern_California

At Weaverville, John Carr was a witness to the sudden melt of snow by the heavy rain and onset of the flood in December 1861 on the Trinity River:

From November until the latter part of March there was a succession of storms and floods... The ground was covered with snow 1 foot (0.30 m) deep, and on the mountains much deeper... The water in the river ... seemed like some mighty uncontrollable monster of destruction broken away from its bonds, rushing uncontrollably on, and everywhere carrying ruin and destruction in its course. When rising, the river seemed highest in the middle... From the head settlement to the mouth of the Trinity River, for a distance of one hundred and fifty miles, everything was swept to destruction. Not a bridge was left, or a mining-wheel or a sluce-box. Parts of ranches and miners cabins met the same fate. The labor of hundreds of men, and their savings of years, invested in bridges, mines and ranches, were all swept away. In forty-eight hours the valley of the Trinity was left desolate. The county never recovered from that disastrous flood. Many of the mining-wheels and bridges were never rebuilt.^[16] 

end quote.

He also notes that the Sacramento River was 20 miles wide from Stockton to Redding. If you drive up Interstate 5 from Stockton think about this for a moment because it means that Interstate 5 would literally be underwater with 10 miles each direction east and west underwater in addition to it being underwater from about Stockton to Redding. IF you aren't used to seeing 20 miles of water think about Los Angeles or Long beach to Catalina island in the Pacific Ocean which is about 26 miles from land at the closest point out into the ocean which is an amazing thought to contemplate too.

He traveled north from I believe STockton? to maybe Red Bluff or Redding on the Steamer Gem which I believe was a flat bottomed boat useful in water not too deep like you also saw during the 1800s in the Mississippi River and other larger rivers still like the Columbia Rive in Washington State. They pulled men out of trees and off barns on the way north who had been trapped by the flooding by the way as John Carr rode north to either Red Bluff or Redding up the Sacramento River. This was mostly how people traveled north during this time because roads hadn't been built at that time much so it was easier to travel by steam boat north rather than ride in a stage coach. I'm not even sure that stage coach rides existed this early in the states history because California had ONLY been a U.S. state for 12 years then. Before that California was owned by either Mexico or Spain.

The flood was so bad that even Sacramento was under 6 to 12 feet of water and they had to move the Capitol to San Francisco then in 1862 by boat because all roads to San Francisco were under water then for 6 months to a year.

But, imagine a flood being so bad that cattle ranching for all intents and purposes mostly ended in California so California went from a ranching state to a farming state after this flood.