BALBOA ISLAND – The Newport Beach Tidelands Management Committee met Oct. 29 to discuss the future of aging seawalls on Balboa Island. City officials and island residents have been trying to come to a consensus of how best to be prepared for rising sea levels predicted by scientists.
Two options were presented during an extensive discussion involving civic leaders, community members and about a dozen residents who live along Balboa Island’s Grand Canal. City staff agreed to flesh out a third alternative to use dredging as a means to extend the life span of some sections of the seawall.
Balboa Island has been no stranger to its streets being flooded by high tides and waves. Portions of the island experienced flooding in December 2010, when the combination of a moderate storm and high tide overflowed onto the boardwalk.
On Dec. 12, 2013, a king tide caused water levels to reach the brim of the seawall on the west side of Balboa Island. The lack of winds or waves that day kept water from flowing over the seawall.
According to the California Coastal Commission’s Sea-Level Rise Policy Guidelines, the combination of eroded seawalls and rising sea levels could result in even the slightest of rain storms having an adverse impact on Balboa Island.
“Sea level will rise enough that even small storms will cause significant damage, and large events will have unprecedented consequences,” as stated in the Sea-Level Rise Policy Guidelines.
Newport Beach recently began assessing the potential for flood damages in light of predictions of a rising sea level.
If not addressed, city officials said Balboa Island could be flooded, citing information from the California Coastal Commission and other scientific sources that contend the sea level could rise between 3 and 6 feet before the turn of the century.
Jamshed Dastur, who sits on the Citizen Advisory Panel of the Tidelands Management Committee, said the wide range of how high the water will reach depends on how aggressively state and federal leaders devise policies limiting carbon output.
The sooner carbon-restrictive laws are enacted and enforced, the greater likelihood sea level rise could be limited to just 3 feet in the next 85 plus years, he explained. However, inaction or delayed legislation means sea level rise could reach 6 feet by 2100.
According to the California Coastal Commission’s Sea-Level Rise Policy Guidelines, scientists project the state’s sea levels will experience a 2 feet rise between 2000 and 2050.
“Scientists now widely agree that the climate is changing and that it has led to global increases in temperature and sea level. Until mid-century, the most damaging events for the California coast will likely be dominated by large El Niño-driven storm events in combination with high tides and large waves,” as stated in the California Coastal Commission Sea-Level Rise Policy Guidelines.
Two options were presented at the Oct. 29 meeting of the Tideland Management Committee, including one plan calling for a new seawall and another looking at repairing existing infrastructure.
A new seawall could cost Newport Beach $32 million but would be functional for 100 years. Making repairs to existing infrastructure would extend the seawall life span by another 25 years. The bill for the repair option would be at about $18 million.
Signs have been placed around Balboa Island to inform locals of the two elevations being considered for the top of a new seawall cap to be constructed to provide flood protection from projected sea level rise.
The upper limit is 10 feet; its bottom edge is 9.5 feet.
Many residents at the meeting asked about the possibility of dredging along the middle of the Grand Canal as an alternative plan to extend the life of the seawalls in that area. City officials said they would study this alternative and present all the options in January 2015.
Dredging would not be able to happen until Newport Beach’s Eelgrass Protection and Mitigation Plan is in place, staff explained.
“We’re trying to determine what’s acceptable for us,” said Dastur, an engineer who spent much of his professional career specializing in marine construction.
A resident of Balboa Island and chair of Balboa Island Improvement Association’s Sea Wall Committee, Dastur said the best way to prevent flooding in one of Newport Beach’s most affluent communities would be to repair unsound sections of seawall and ensure the height of the barricade is 9 feet all around.
This would mean increasing the seawall height as little as 6 inches in some portions of the island or as much as 16 inches in others.
Some residents are skeptical of building a 9-foot-high seawall.
John Doughty, who owns JD’s Big Game Tackle on Balboa Island, wrote in an email to Newport Beach staff that people regularly walk atop the seawalls. Adding 6 inches to 1 foot to the seawall would increase the risk of injury. He also questioned the economic impact of a taller seawall since many people sit on the seawalls during the annual Christmas Boat Parade. He questioned if guests who visit the island to watch the holiday may stop doing so if heights were increased, which would translate in fewer people patronizing Balboa Island businesses.
The current seawall is about 85 years old, about one decade beyond its life expectancy. City officials believe the existing walls are subject to seismic risk. Newer seawalls could have a life expectancy of 85 to 100 years.
Naples Island in Long Beach built its current seawall after a major earthquake in 1933. Now at the end of its life expectancy, the city of Long Beach adopted a plan to replace the seawall.