“The Great Central Valley of the state is under water — the Sacramento and San Joaquin valleys — a region 250 to 300 miles long and an average of at least 20 miles, or probably three to three and a half million acres!” — William Brewer in his book, “Up and Down California in 1860 — 1864”
It is 103 degrees today. The last thing you are probably thinking about is flooding.
But since you live in in the Central Valley, it is something you should give serious thought even as you curse opening your July electrical bill.
Senate Bill 5 — the knee jerk reaction to Hurricane Katrina and New Orleans — gave us the 200-year floodplain protection mandate. The solution is partial at best and therefore ineffective as it doesn’t take into account the entirety of catastrophic flooding events in California.
First, let’s clear up a misconception. A 200-year flood doesn’t mean it will happen once every 200 years. It essentially is seen as an event that has a 1 in 200 chance of happening in any given year. How we rate the chance of flooding is way off base for two reasons. Have you noticed that we’ve experienced more than a few 100-year floods in the last 60 years? They’re happening with more frequency as more and more surface area becomes impervious with the building of rooftops, parking lots, and roads. Also, the measurement itself is myopic. It is based on observed weather patterns of the last 150 years instead of reoccurring climate shifts over centuries.
The current climate change debate really muddies up the water when it comes to the historic framing of prolonged droughts and mega floods involving the piece of geography we call California and the rest of The West. That’s because it is keeping climate cycles that naturally occur in California out of the debate. There’s plenty of evidence in research for one to safely conclude it is not greenhouse gas responsible for California’s recent droughts and serious floods as it is the natural climate cycles. Climatologists long before “global warming” became part of the political vernacular, have argued our current stretch of weather in California going back 150 plus years is not the norm as are periods of prolonged droughts spanning decades punctured by massive floods.
Let’s go back to 1861-1862, some 155 years ago. What people at the time referred to as “unprecedented” snowfall in November and December of 1861 covered the Sierra. It was a weather year where San Francisco and Sacramento received four times the normal rainfall in a three-month period ending in February 1862. Nevada City in the Sierra foothills during the same weather year received over 108 inches rather than the normal 55 inches. All that rain from warm storms melted the unusually heavy early Sierra snowpack.
Reports by government agencies and newspapers of the day told of how the Great Central Valley was turned into a giant lake. More than 800,000 cattle drowned — 25 percent of the entire state’s head count. Seven out of every eight homes were destroyed. Roughly 30 percent of the state’s improved property was destroyed.
It is the event that put Sacramento under 10 feet of water promoting the eventual conversion of first floors into basements when the city rebuilt. Leland Stanford — on his inauguration day as governor— had to travel by rowboat from the governor’s mansion to the State Capitol to be sworn in.
It also flooded Stockton for months.
While all of this seems like ancient history, it isn’t in the realm of weather cycles.
Levees have been raised and dams built since then. But what we have in place is not enough. There were 379,994 residents in California in 1860 as opposed to 39.25 million today. And if climatologists are right about the climate cycles and the last 150 years being an anomaly when it comes to weather, California’s future will include mega-droughts that will make those we’ve experienced in recent decades seem like wet years as well as massive floods on the scale of 1861-1862 and larger.
It has everything to do with ocean temperatures, the trade winds, and the geology of California with its Coastal Ranges that trigger the first precipitation and its much loftier Sierra that wrings out the bulk of the moisture. 
Requiring 200-year flood protection where there is urbanization is prudent. What isn’t prudent is not expanding the state’s ability to store water not just for summer use and dry years but also to manage its journey to the ocean.
Besides bigger and stronger levees and more storage, we also need to dredge critical channels such as the Lower San Joaquin River where sediment buildup — whether it is runoff from Westside farm irrigation practices that have since been changed or from massive flood events — have severely reduced the water volume that can be moved between levees.
We are fools to think we can control nature. That said, we are even bigger fools if we don’t learn how to live with how the Earth works.
Entire civilizations have been wiped off the face of the planet because they couldn’t adjust to mega droughts or were overwhelmed by a winter of nature’s unleashed fury.
We have not — and never well — conquer nature when it comes to rain and snow. But what we can do is manage how we deal with it. Given the drought — which may be over unless we slip back into a dry cycle — and this year’s “record” snowfall based on 150 years of recorded data against 4.56 billion years of the Earth’s existence, it is clear we are skating on thin ice.