The city of Half Moon Bay is examining the impact of sea level rise and erosion on its southern coastline, which could harm the most significant contributor to the city’s economy.
According to ongoing studies from San Mateo County and its environmental consulting firm Integral Consulting, parts of the Ritz-Carlton, Half Moon Bay, the Golf Links and Ocean Colony neighborhood are at risk of erosion and flooding as a result of sea level rise.
On Dec. 21, the City Council voted to pay $25,000 to move into the second phase of the city’s Sea Level Rise Vulnerability Assessment and Fiscal Impact Assessment, which will determine how to deal with coastal hazards, identify strategies like seawalls, sand retention, and sand dunes, and provide public outreach. The agreement will be finalized at the council’s Jan. 19 meeting.
The decision is meant to offer a more targeted approach compared to San Mateo County’s efforts to map and forecast sea level rise in coastal areas. In 2018, San Mateo County conducted its Sea Level Rise Vulnerability Assessment and Adaptation Plan for the bayside and much of the Coastside, but there was a gap in available U.S. Geological Survey data from the southern end of Half Moon Bay near Ocean Colony to the San Mateo-Santa Cruz county border.
In 2019, the county surveyed that area through its South Coast Sea Level Rise Risk and Solutions Study and released draft maps in fall 2021. The maps show stages of dune and cliff erosion from the current sea level rising up to 0.8 feet, 1.4 feet and 4.9 feet. The maps present so-called “combined hazards” zones that forecast the impact of a 100-year storm event. At each calculation, more of the coast is lost, with the farthest extent of the erosion, at 4.9 feet, hitting the Ritz-Carlton.
Hilary Papendick, a program manager with the San Mateo County Office of Sustainability, said the county spent around $200,000 on its assessments and would not be involved with the city’s new study. Papendick said the county plans to release the final report sometime in early 2022.
In November, after the county released its South Coast study, the city staff contacted Integral Consulting to discuss expanding the study to include Ocean Colony and the Ritz-Carlton. The city signed a contract with the firm to complete a $30,000 vulnerability and economic impact assessment that was funded by the city’s Public Works Department because there was no specific capital project for the work.
As one might assume, the study found that nearly 5 feet of sea level rise will have more drastic impacts for the Ritz-Carlton, the Coastal Trail and much of the South Coast, including 123 structures and 15 miles of trails and coastal access points. It highlights that residents near Pescadero, Martin’s Beach and Tunitas Creek are particularly vulnerable from creek and stormwater overflow, and notes that Pigeon Point Lighthouse, Cal Fire Pescadero Station 59 and the Gazos Creek Gas Station are at-risk locales.
In addition, the county identified 4.5 miles of Highway 1, from Bean Hollow State Beach to Pescadero, as susceptible to erosion, along with 551 acres of potentially vulnerable agriculture land and 121 acres of planted fields, mostly low-lying areas east of the Pescadero Marsh Natural Preserve, Papendick said.
Given that the Ritz-Carlton is the biggest contributor to Half Moon Bay’s transient occupancy and property taxes, the council and staff felt it was a priority to mitigate the effects of coastal erosion. Public Works Director John Doughty said this was an important step to make these projects available for any grants.
Doughty said neither Ritz-Carlton nor the Golf Links has committed funding to the city’s expanded study yet, but that staff was aware of the efforts, understood the issue and were willing to share information with the city.
“Their investments and commitments are going to be significant over time,” Doughty said. “From staff’s perspective, this is a small amount of money to at least get the ball rolling and start the conversation.”