Sea Level Rise and Its Impact on Huntington Beach
By Shirley Dettloff
that are most vulnerable to sea level rise.
More information can be found on the
City of Huntington Beach website
We now see the State Legislature taking action, as well as the Coastal Commission and local jurisdictions including the City of Huntington Beach. The Coastal Commission requested that all coastal communities review and mitigate the impacts of Sea Level Rise. The city applied for funding to do such a study and received a $200,000 grant from the Coastal Commission. This is the second study the city has done and it is available to the public at the city’s website and is entitled Final Sea Level Rise Vulnerability Assessment.
The city, with the assistance of consultant Moffatt & Nichol, looked at several factors which would play a huge role in determining which areas of our City would be subject to sea level rise. They studied areas that naturally tended to be flooded, areas where there are infrastructure projects such as the Sanitation District, roadways that could be impacted, transportation corridors, recreation areas and of course housing. The areas that were studied in depth were Huntington Harbour, including Sunset Beach, the Bolsa Chica, the downtown city area, and south Huntington Beach, including the Huntington Beach Wetlands.
Starting in the northern part of the City, Huntington Harbour was studied and found to be the most vulnerable. It is tidally influenced and also receives storm water runoff from major regional flood control channels. Subsidence has been reported in the Huntington Harbour areas due to historic oil production activities. Seawalls and bulkheads around the Harbour are the primary defense to rising sea levels and subsidence can directly impact the ability of these structures to accommodate sea level rise. Also, a number of storm water outfalls, storm water pump stations and sewer lift stations lie within the study area resulting in high over hazard exposure.
Going south to the Bolsa Chica area. This area contains wide, sandy beaches backed by the Bolsa Chica Wetlands. It also has a major transportation corridor, Pacific Coast Highway, which in the past has received major flooding. If the oil field continues to function, this is another consideration as to how to address this issue. The wetlands has been restored and is functioning as a major wetland. What a major storm would do to this resource is still a question. One very important factor is that this wetlands absorbing so much of sea level rise, may protect those homes that are surrounding the wetland. This area is considered to be an area receiving minimal impacts.
How will the downtown area which extends from Goldenwest St. to Beach Blvd. be impacted? It includes wide sandy beaches and concentrated areas of residential and commercial development. There are two important structures in the area which include a condo project and the pier. Because most of this area is at a higher elevation than other areas of the city, it appears that sea level rise would have minor impacts.
Lastly the area from Beach Boulevard to the Santa Ana River which has two major facilities, the AES Plant and the Orange County Wastewater Treatment Plant. These facilities are now looking at adaptive measures that could give them protection, but will require hydraulic studies and significant changes. This area is protected by a system of levees along regional flood control channels thus giving them some protection.
But this is just the beginning. Future studies will be needed to know how we should address these impacts. Numerous recommendations have come forward such as moving homes or facilities in danger back from the coast, known as managed retreat, moving highways away from the coast, and relocating railroad corridors. These are merely ideas, but this issue must be addressed.
In conclusion let me quote Donne Brownsey, Vice Chair of the California Coastal Commission who says, “Sea level rise doesn’t always raise widespread concern among the public because it doesn’t display its threat as dramatically as other disasters. It’s a slower moving crisis than a wildfire or hurricanes, but this is an urgent impactful issue.”
Coming in the Winter 2022 Tern Tide: Update and a status of the City’s efforts and legislative action with SB 1 and SB 83.