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Managed Retreat Sinks
Don Mosier | Rimini Road

The Planning Commission voted 4-1 (Commissioner Posner opposed) at its February 13th meeting to approve the Sea Level Rise Adaptation Plan created by the Sea Level Rise Technical Advisory Committee (STAC) and its consultant, Environmental Sciences Associates (ESA). After 2 hours of spirited discussion about the merits (or lack thereof) of including “managed retreat” as an adaptation strategy for private property owners, the vote supported the compromise reached in December by the STAC. Managed retreat, moving buildings out of harm’s way, was supported for municipal buildings like the firehouse and public works building, but was deleted as a strategy for private property owners. Coastal Commission staff strongly recommended retaining managed retreat as a last resort strategy, but several speakers objected to this as ill-defined and unlikely to preserve public access to the beach, a key goal of the Coastal Act. The consensus of the Planning Commission was that it was too soon to consider managed retreat until we see how other adaptation strategies work and whether or not new technologies will be developed to combat sea level rise.

Long term planning must make assumptions based on past events and project them into the future. Table 1 from the Adaptation Plan is reproduced below, which shows the range of estimates for sea level rise in Del Mar. Major adaptation strategies would be triggered by 18 in. of sea level rise, which could occur in the 2040-2050 time frame.

TABLE 1. Sea Level Rise (SLR) Scenarios Used in Adaptation Plan

  2030 2050 2070 2100
Low SLR 2 in. 5 in.   17 in.
Mid SLR 5 in. 12 in. 20 in. 37 in.
High SLR 12 in. 24 in. 38 in. 66 in.

Eighteen inches of sea level rise may not seem like a lot, but that translates into 150 ft. of beach run-up, and overtopping of sea walls during high tides and storms. Planning for moving major public infrastructure will take time and money, lots of it. Planning Commission Chair Bakker emphasized that this is a global problem and the federal and state governments need to step up with clearer programs and significant financial help to really implement adaptation strategies. The Del Mar Adaptation Program now heads to City Council for approval, and then to Coastal Commission as a revision to our Local Coastal Plan.

 

 

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