Del Mar expects state to accept its rejection of managed retreat

Del Mar is optimistic that its rejection of “managed retreat” for adapting to sea-level rise will be accepted by the state Coastal Commission, City Councilman Dwight Worden said last week.

“Rejecting managed retreat is central to our plan, and having the coastal staff agree with our position is very significant and encouraging,” Worden said by email.

Managed retreat can take several forms. In some cases, a public agency will buy coastal structures and move or demolish them to leave open space for the advancing ocean. The strategy could be limited to banning new construction on vulnerable property, or simply a requirement that buyers be notified of the hazard.

Other coastal communities in San Diego County are built predominantly behind bluffs at least 60 or 70 feet above sea level. Those areas see sea-level rise as less of an immediate threat and generally have agreed to consider managed retreat.

Del Mar has about 600 homes in a low-lying area on the north end of town, nearly one-quarter of the small city. It has one of the highest median home values in the state — $2.5 million according to Zillow. The high cost of real estate alone makes managed retreat impractical there.

With that many valuable homes and no other build-able land, retreat is not an option, the City Council and residents have said. They plan to rely on sand replenishment and seawalls to protect low-lying homes for the foreseeable future.

A Coastal Commission staffer said last week that, though the decision is not final, the city’s approach is under consideration. Even if the staff recommends approval, the 12 voting members of the commission could disagree.

The commission staff’s written recommendations on Del Mar’s managed retreat policy, along with other proposed modifications, will be released for public review a few weeks before the commission’s mid-October meeting, said Madeline Cavalieri, a district manager in the agency’s San Diego office.

“We recommend local jurisdictions look at a range of options,” Cavalieri said. “The commission is not dictating what the outcome will be.”

The commission asks cities to evaluate all the strategies, but not necessarily to implement them, she said.

Armoring the coast by building seawalls, pilings and rock revetments is another strategy for adapting to sea-level rise. Yet studies show those methods accelerate beach erosion and compound the problem. The Coastal Commission usually approves such measures only to protect existing structures that are in immediate danger.

“It’s important to keep in mind that all these adaptation strategies need to be phased in over time,” Cavalieri said, and that what works now might not work years down the road.

Del Mar’s sea-level-rise adaptation plan is part of its proposed Local Coastal Program amendment. An approved Local Coastal Program gives the city the authority to decide local development issues that otherwise would go to the Coastal Commission.

San Diego County coastal communities have been spending federal, state and local money to pump sand onto eroding beaches for decades. Wider beaches attract more tourists and protect coastal bluffs, homes and infrastructure such as roads.

However, the replenishment strategy is likely to become more difficult and costly as sea level continues to rise and sand becomes more scarce.

Conservative estimates predict the mean high tide on the California coast will increase by 1 to 2 feet by the end of the century, and some recent estimates say it could go up as much as 6 feet or more.

— Phil Diehl is a reporter for The San Diego Union-Tribune