When it Comes to Rising Sea Levels, Coronado Is Treading Water - Voice of San Diego

Science/Environment UNVEILING THE UNSEEN

When it Comes to Rising Sea Levels, Coronado Is Treading Water

Coronado’s city leadership acknowledges it could be facing dire circumstances. It also acknowledges that thus far, it has taken no steps to plan for such outcomes.

Some coastal cities are rushing to prepare for rising sea levels, but Coronado – surrounded almost entirely by the ocean and a bay – is not one of them.

Sea-level rise could affect what’s on Coronado already, as well as future development in the city and Navy property. Everything from a new city beach bathroom to a new $700 million Navy facility could be impacted. As oceans rise, beaches may erode, tides will creep in and storms will cause worse floods.

While the Navy has made some preparations of its own for climate change on Coronado, the city itself has not.

Though the major effects are still decades away, Imperial Beach, just south of Coronado, is talking now in clear terms about the costs and consequences of rising oceans.

David Revell, a climate scientist working to prepare Imperial Beach for sea-level rise, said that Coronado has been absent from regional discussions.

“So they need to be in the room discussing this,” Revell said during a recent Imperial Beach City Council meeting.

Coronado’s city leadership acknowledges it could be facing dire circumstances. It also acknowledges that thus far, it has taken no steps to plan for such outcomes.

“If there is significant rise in sea level, it could have potential effects on many parts of the city,” Coronado Mayor Casey Tanaka said in an email.

Yet the mayor said the Coronado City Council has “not actively discussed plans or policies for sea level rise.”

Plenty of studies have spelled out the risk facing Coronado, including a 2012 study by the San Diego Foundation, a 2013 study by Climate Central and a 2015 study by the Navy.

And the Navy – perhaps Coronado’s most significant resident – has stark concerns for the island over the next century.

Up to $3.7 billion in Naval assets and certain civil infrastructure are vulnerable to damage from sea-level rise and associated flooding, according to a worst-case scenario considered by the Navy. That scenario forecasts an ocean that rises 6.5 feet.

The Navy report also estimates that 95 percent of its beach training areas – the narrow bands along the beach between the water and the dunes – could become unusable at times, again in a worst-case scenario.

On its face, the Navy seems to grasp the seriousness of the threat better than Coronado. But it’s not yet fully incorporating the worst-case scenario into its actual plans. As it begins work on a major $700 expansion on Coronado’s Silver Strand, the Navy is preparing for that facility to handle up to three feet of rising seas, even though its own models consider up to 6.5 feet of sea-level rise.

The California Coastal Commission in 2014 questioned why the Navy wasn’t preparing for the worst-case scenario.

Mark Delaplaine, the manager of the commission’s ocean resources and federal consistency division, said he knows the Navy agrees sea-level rise is an issue, but said it has options in the future that other developers and landowners do not. For instance, if the worst-case scenario comes to pass, the Navy could abandon Coronado and move troops elsewhere.

“They have the institutional ability to do that – a homeowner with a small bluff-top lot doesn’t have that,” Delaplaine said.

The Navy has not yet responded to a request for comment on why its new facility does not prepare it for the magnitude of sea-level rise it considers possible.

Officials in coastal communities across the country are facing a difficult choice: Do everything they can to protect their community now at great cost, based on modeling that is uncertain; or do little and gamble the future.

Coronado has opted so far for a path closer to the latter.

On the south side of the Hotel Del Coronado, along the Pacific coast, the city of Coronado is planning to build a new public bathroom building. City officials are resigned to the fact that those bathrooms will be regularly flooded.

The city planned for the bathrooms to flood two to three times a year for the next 10 years. They’ll be closed, cleaned and reopened.

If flooding from storms and high tides become more frequent and severe – an expected consequence of sea-level rise – the restrooms could handle a couple of feet of water reaching the tops of toilets, though the city would have to repair some damage, said Cliff Maurer, director of Coronado’s Public Services department.

But if sea-level rise occurs at a higher rate, then the restrooms – and other parts of the island— might have a problem. The city isn’t planning for the worst-case scenario.

“Our general position on sea-level rise is it’s not an imminent issue,” Maurer said.

Sea-level rise predictions vary greatly. If the worst-case scenarios come to fruition by the end of the century, homes, infrastructure, roads and beaches in Coronado might not withstand the flooding and erosion.

The Intergovernmental Panel on Climate Change projects sea levels could rise by more than three feet by the end of this century. The U.S. Army Corps of Engineers has models showing more than five feet. The National Oceanic and Atmospheric Administration predicts up to six and a half feet by 2100.

The city also isn’t planning on preparing any of its existing infrastructure, like low-lying roads or storm drains, for higher water.

“Some of the storm drains are below levels of high tides,” Maurer said. “That’s an issue, but that’s not a pressing issue. If storm frequency and storm energy increases, then it’s a pressing issue. Certainly the intensity of the storms and the frequency of the storms is more troubling than sea-level rise itself.”

Coronado City Councilman Bill Sandke has taken a personal interest in sea-level rise since he was appointed to the San Diego Association of Governments’ shoreline preservation committee.

“I was envious reading the Del Mar sea-level rise study,” Sandke said, referring to an eye-opening report on threats posed by sea-level rise to that coastal community. “Their bluffs certainly present a more immediate issue than with our beach, but I would welcome us paying more attention to sea level rise and the environment around us.”

Coronado hasn’t done any studies on how sea-level rise might impact it, like Imperial Beach and Del Mar have, Sandke said, “but we have certainly seen the inundation maps prepared by other researchers.”

The San Diego Foundation study expressed concern over the next century for flooding of the Coronado Cays residential development and all the houses east of First Street.

Part of the reason folks in Coronado may feel less of an urgency from sea-level rise is that some of their beaches – the north and central ones – have actually been getting wider.

But this year’s winter gave a taste of what increased flooding and erosion could bring to the south beach. The city needed to move sand from the other beaches to protect the paseo, a path between the Hotel Del and water, during three different high tide cycles.

Trisha Trowbridge lives in a condo on the south side of the beach. She sends the Coronado City Council pictures of high tides from her apartment regularly.

There are rocks and stone steps between her building and the ocean. Over the years, Trowbridge has noticed the water slowly encroaching further inland.

Photo courtesy of Trisha Trowbridge
Photo courtesy of Trisha Trowbridge

“I can’t speak for everyone in my town, but last winter was a wake-up call for me,” Sandke said.

Last year, coastal communities got a taste of what rising seas can do when high ocean tide surged into the storm drain system, part of record-setting “king tides.” Local scientists say these tides are getting more severe, are causing flooding more often and are a harbinger of things to come.

Maurer said Coronado has wide beaches and existing rocks and seawalls armoring the coasts.

Maurer says another reason Coronado isn’t acting more aggressively is that it isn’t as vulnerable as other places. And if things change, he said, there’s time to react.

Del Mar and Solana Beach have bluffs that are eroding and threatening structures, Maurer said, and Imperial Beach’s layout leaves a lot of infrastructure at risk. He said none of that is true of Coronado.

“We’re exercising prudence,” Maurer said. “If we make changes, it won’t be overnight, but we’ll make the proper adjustments.”

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