West Coast Flooding Expected To Steadily Increase, New Report Warns

The high tide flooding that inundated the streets of Newport Beach's Balboa Peninsula over the Fourth of July weekend will grow more common throughout the state - and nation - thanks to rising seas, according to a recently released National Oceanic and Atmospheric Administration report.

The report noted that there were three high tide flooding days at NOAA's Los Angeles monitoring station in 2019. But underscoring growing state and local concerns with damage that rising seas pose to the coast, the agency predicts annual high tide flooding in the area to spike to six-10 days by 2030, and 15-40 days by 2050.

"Evidence of a rapid increase in sea level rise related flooding started to emerge about two decades ago, and now is very clear," the report said. "NOAA's National Weather Service is issuing record numbers of watches [and] warnings for coastal flooding. This will become the new normal unless coastal flood mitigation strategies are implemented or enhanced."

Noticeably absent from the report is mention of the key contribution of climate change and global warming to rising seas, although the agency's website describes sea level rise as "mostly due to" melting glaciers and the expansion of warming waters.

Asked during a news teleconference about climate change not being addressed in the report, NOAA's Nicole LeBoeuf said it played a factor in the trend of increased flooding, but the report wasn't intended to explain the causes of rising waters.

"It's a little different topic, but they are related," she said.

The administration of President Donald Trump, a climate change skeptic, oversees the agency, but LeBoeuf said there was no political vetting of the report before it was released.

Drastic trends

Southern California has seen an unruly foreshadowing of what scientists say the future holds.

Recent events have included the Balboa Peninsula flooding, the collapse of beachfront walkways in Capistrano Beach, and the temporary closure of San Onofre State Beach because the parking lot got washed out. King tides typically flood parts of Long Beach and bubble up through Pacific Coast Highway storm drains in Huntington Beach. In 2017, Newport Beach raised the seawall on Balboa Island by 9 inches as fortification against rising seas.

As ominous as the new report is for California, agency data from 98 coastal locations nationwide documents even more serious high tide flooding in the Gulf of Mexico and East coasts, with far worse projections for the future.

Eagle Point in Texas' Galveston Bay had 64 days of high tide flooding last year, for example, worst in the nation. Boston is predicted to have 20-35 flood days by 2030. Virginia's Sewell Point is expected to have 65-170 days by 2050.

Along the East and Gulf coasts, 19 locations broke or tied their all-time high tide flooding records in the past year.

But coastal waters pose significant threats nationwide, and California's risks are increased by bigger waves than found on the East and Gulf coasts.

"High tide flooding is more than twice as likely now as it was in 2000," the report says of national trends. "Flooding that decades ago happened only during a severe storm now occur during a full-moon tide or with a change in prevailing winds or current."

High tide flooding for California is defined by NOAA as being 1.9 feet above the average daily high tide, which was calculated using data from 1983-2001. Because of natural and man-made protections, including wetlands and seawalls, not all high tide flooding days as defined by the agency result in flooding. But because of coastal contours, currents, high surf and storms, flooding also can occur on days not defined as high tide flooding.

California has less high tide flooding than the East and Gulf coasts largely because it has a smaller continental shelf, said NOAA oceanographer William Sweet. But that bathymetric feature also contributes to bigger waves, which were not factored into the report's high tide flooding calculations, he said. Twelve California locations were monitored for the report.

In the case of the Fourth of July weekend on the Balboa Peninsula, high tides and big surf combined to cause the inundation, catching officials off guard and forcing workers to scurry to build up a beach berm to minimize additional flooding.

California's crisis

With rising seas and crumbling bluffs increasingly jeopardizing coastal buildings, roads and train tracks - and with ocean-height projections increasing - there's growing testimony that the state has been woefully inadequate in addressing the issue.

In Orange County alone, a 6-foot rise would inundate 11 square miles of land and 20 miles of road, affecting 50,000 residents, Coastal Commission scientist Mary Matella told commissioners last year. A study by the U.S. Geological Survey found that if no action is taken, two-thirds of beaches in Southern California could be swallowed by the ocean by 2100.

Statewide, $8 billion-$10 billion of property will be underwater by 2050, according to a December report from the state Legislative Analyst's Office. Storm surges and big surf could push the waters - and damage costs - even higher, it said.

Shoreline armoring, such as seawalls and boulders, is a popular strategy among beachfront homeowners but is generally discouraged by the Coastal Commission because it leads to the disappearance of beaches.

Instead, the commission and environmentalists favor enhancing dunes and wetlands to bolster natural buffers. Another preferred strategy, dubbed "managed retreat," involves moving or demolishing waterfront infrastructure and buildings to allow the ocean and beaches to advance landward.

The commission is distributing grants to cities and counties to update their state-required Local Coastal Plans with sea level vulnerability assessments and adaptation plans. More than half of the state's 61 coastal cities and 15 counties have completed or are working on adaptation plans.

But the Legislative Analyst's Office said efforts need to be accelerated, and many environmentalists agree.

The crystal ball

Nationwide, sea levels have risen 1.1 feet since 1920, a trend that's been accelerating over the past decade, according to the report.

"This level of safety was deemed necessary because new models regularly predict more sea level rise, not less, and the analysis did not account for king tides or storm events," said Justine Kimball, senior program manager for the state Ocean Protection Council's Climate Change Program.

The council's projections, based on NOAA tidal data, are important because they set the standard used by the Coastal Commission and local governments to develop adaptation strategies.