Discover the 5 Most Flood-Prone Towns in California

Even though California has a reputation for being sunny, it is also prone to devastating floods. In 1862, a flood so bad turned the Central Valley into a lake. Most of the state isn’t immune to water deluges, but where is the risk the worst? We’ll discover the 5 most flood-prone towns in California now.

5. City of Newport Beach

Newport Beach is a coastal city in the greater Los Angeles area. It has a population of just under 85 thousand people.

In exceptionally rainy years, Newport Beach floods. King tides also affect Newport Beach and can inundate low-lying areas with water.

The area that usually takes the biggest hit when flooding occurs is the Balboa Peninsula and Balboa Island. As a whole, almost 20 percent of all properties in the city are at risk of severe flooding.

In the middle of the City of Newport flows the San Diego Creek. San Diego Creek is the primary water source for Newport Bay. This means that the city not only experiences threats from the Pacific Ocean, but it also is vulnerable to rains upstream in the mountains.

The headwaters of the San Diego Creek are in the Santa Ana Mountains. This means that rains far to the east at high elevations can flood Newport Beach.

4. Crescent City

A bit more than 6600 people live in Crescent City which is an area that holds the distinction for having the largest tsunami threat in California. 32 recorded tsunamis have occurred since 1933 with the Japanese tsunami in 2011 killing a person. In 1964, the Good Friday Earthquake in Alaska caused a tsunami that killed 11 people in Crescent City.

The Mendocino Ridge in the ocean off of the coast of Crescent City is a westward ridge that causes tsunamis to intensify. This is amplified by the position and shape of the shoreline at Crescent City, which is an inland curve.

3. City of Watsonville

The City of Watsonville has over 52 thousand people. Along with Watsonville, other communities in the Pajaro Valley Watershed are at imminent risk of devastating floods. In fact, in March 2023, a levee failure in the town of Pajaro displaced over 3 thousand people.

Some of the levees protecting this area in Santa Cruz County on the Central Coast are over 100 years old, and funding requests to repair them have been ignored since the 1960s. As a result, a 7-year storm destroyed a levee and flooded a town. Mass devastation is possible if a larger storm rolls through the area before the levees are reinforced.

Within Watsonville, over 35 percent of all properties are at risk of bad flooding. Over 45 percent of roadways will be severely affected by a large flood which may block people from evacuating.

2. City of Sacramento

Sacramento, the capital of California, lives under the constant threat of severe flooding as levees are the only reason that huge population centers within the city are dry. The downtown area, after a devastating flood in the mid-1800s, was raised 14 feet to avoid such a catastrophe happening again. More than 500 thousand people live in Sacramento proper with almost 2.5 million people occupying the greater Sacramento area.

Despite massive flood protections in the city, infrastructure is crumbling. As it stands today, over 40 percent of all properties within Sacramento County are at risk of severe damage should a large enough flood occur. Since infrastructure in some places in the city is crumbling, this risk rises every year.

Sacramento is built at the confluence of the American and Sacramento Rivers. As a result, lots of water pumps through the area when excessive rainfall occurs in Northern California.

While the Yolo Bypass to the west of Sacramento alleviates yearly flood waters by providing an emergency storage ground, if the right storm hits, it still won’t be enough. The Sacramento Weir will soon be doubled in size so that more floodwaters can be released into the Yolo Bypass should the need arise. This project is projected to be completed by the end of 2026.

The Natomas Basin in Sacramento

In the greater Sacramento area is a geographic feature known as the Natomas Basin which is home to over 100 thousand people. Around this basin, which is a natural floodplain, a large proportion of the levees are in a state of neglect. If the levees fail or crest, a catastrophe rivaling or surpassing that of Hurricane Katrina in New Orleans will occur.

In many areas in Sacramento, and to a lesser extent in other parts of the state, homeowners are barred from buying flood insurance. This is because loans with any kind of federal backing do not require insurance in areas with functioning levees at the time of a home’s sale. Because of this, many residents in the Sacramento area are not protected should an inevitable flood destroy their homes.

1. Stockton Metropolitan Area

The Stockton Metropolitan Area is located in California’s Central Valley south of Sacramento. It is home to over 800 thousand people, and it is growing quickly due to its proximity to the San Francisco Bay Area.

This metro area is situated on the San Joaquin River which drains into the San Joaquin Delta. The Delta dumps into a series of bays ending in the San Francisco Bay.

Due to a decrease in funding for flood control measures like levee maintenance, the levees keeping the San Joaquin River contained around Stockton are neglected. Over 235 thousand people live in areas that are only dry because of these levees, and if one breaks, over 10 feet of water will sweep over the landscape destroying property and lives in the process. If a big flood happens, over 90 percent of Stockton will be decimated.

While it will probably take a massive 200-year storm or stronger to cause this kind of destruction, some of the oldest levees may give way well before this. That’s because seepage on some of the oldest levees is an ongoing problem. Water gets under a levee and weakens it, which can unexpectedly bring the whole levee down.