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When Sea Level Rises, How Long Can Mission Rock Survive?

San Francisco Public Press
 — Dec 2 2015 - 2:51pm

Voters approved Giants’ $1.6 billion waterfront development, but environmental questions linger

Mission Rock is a now lonely parking lot adjacent to San Francisco Bay, a tempting canvas for development in a city desperately in need of homes. But it is also a risky place to build because of a slow-moving but massive problem few politicians and business leaders are currently talking about: sea level rise.

The expansive slab of landfill is one of the lowest-lying areas of Mission Bay, the 303-acre neighborhood that has been under construction for more than a decade in an area that experts say could be occasionally or permanently submerged as bay waters rise by many feet before the end of the 21st century.

The project’s sponsor, the San Francisco Giants, won permission from the voters on Nov. 3 to move forward with a development plan, estimated to cost $1.6 billion, to build between 1,000 and 1,950 residential units, a new location for Anchor Brewing Co. and 8 acres of open space. It was the size of the buildings the Giants needed approval for. The plan is to blow past the otherwise maximum zoned height of 40 feet, soaring instead to 240. The developers say this helps the city by increasing housing density.

But neither the language of Proposition D itself, nor the fusillade of campaign literature dropped on doorsteps around the city in support of the measure, talked about protection from rising sea levels.

Most of the debate centered around housing, bay views and transportation. But water levels will certainly be an issue in a brand-new neighborhood that would require the city to install new plumbing, electricity and other infrastructure.

The Giants said they had engineering and financial solutions to address future flooding risk. The plan is to raise the grade of the land by several feet to postpone flooding due to sea level rise by several decades. Another part of the so-called adaptive management strategy would be to raise money through yearly neighborhood taxes to pay for costly protective fixes in the future.

Would elevating the buildings be enough? In September 2014, city officials received a draft report they commissioned from outside environmental consultants that said the neighborhood would need to be protected from sea level rise either by a massive sea wall or re-engineered buildings. One suggestion was to turn Third Street into a levee to protect most of Mission Bay. In this scenario the portion of the neighborhood between Third Street and the water, including Mission Rock, would utilize a series of floodable streets or canals to minimize water damage to structures.

This is the second time in as many years that a proposition went to the ballot to approve a high-density megadevelopment at the water’s edge. In 2014, San Francisco voters overwhelmingly approved a similar measure for a mixed-use development for the derelict industrial zone at Pier 70. Proposition F increased the height limit from 40 to 90 feet.

Around the bay, developers are planning or currently building at least 27 major commercial and residential complexes on land that might be threatened by sea level rise by the end of this century. That land — roughly the area below 8 feet in elevation, which represents the high end of current predictions for permanent rise plus extreme storm surge, is estimated to be worth at least $21 billion.

Cities around the Bay Area, including San Francisco, continue to issue dozens of permits for plans like these, even when they address future flood risks vaguely — if they do at all. Experts in environmental planning say more regional coordination and legal changes would allow local governments to modify or even prevent new development that might necessitate expensive future solutions, such as creating even more extensive seawalls than are currently needed to protect existing bayside neighborhoods.

A 2012 study of the effects of climate change on the West Coast, published by the National Research Council, found that average high tides will most likely be 3 feet higher permanently.

While this amount of sea rise would put nearly all of the current shoreline at Mission Rock underwater, most computer models also have a statistically less probable but still possible upper range. Under several predictions, seas would rise about 4.6 feet by 2100. With 3.4 feet of additional surge in a “100-year storm,” the total rise would total 8 feet on a really bad day.

It is hard to plan for sea level rise because the uncertainty in future global fossil fuel emissions makes global warming impossible to forecast perfectly. Climate researchers predict that sea level rise will only accelerate by the end of this century as ocean waters expand and glaciers melt.

According to records from the San Francisco Planning Department, in the last five years the city has approved more that 50 projects that are below the 8-foot elevation zone, with estimated development costs of nearly $5 billion.

Under the direction of Mayor Ed Lee, a new committee is coordinating a “high-level assessment” of risks and vulnerabilities, and could recommend stricter rules for future private development. City officials have said that any new regulation should be written with a nuanced view of risk, determining more than simply whether a new building would flood, but also by the extent of the potential damage.

In response to criticism in a report from a civil grand jury impaneled to review sea level rise policies, Lee has said it “may be unwise — and expensive — to require immediate measures to adapt to wide-ranging, highly uncertain sea-level rise projections further out in time.”

But so far, sea level rise seems to register next to no mention in the public agenda or on the ballot itself as voters consider big changes to the waterfront.

In the debate over Mission Rock, more immediate concerns carried the day, including how to alleviate the housing shortage.

With some political arm-twisting, Supervisor Jane Kim was able to secure 40 percent of the new housing as “permanently affordable” — homes with rents set artificially lower than what the market will bear. After boosting that portion from an earlier pledge of 33 percent affordable, the baseball team won the support of all 11 members of the Board of Supervisors.

Larry Baer, president of the Giants, told the San Francisco Chronicle that the team was responsive to the needs of the community. “We think we have a proposal that really speaks to the issues of the city today, in real time.”

This story appears in the Winter 2016 print edition. For interactive maps, a review of the science and the story of how Bay Area planners and developers are grappling with a changing coastline, see the summer 2015 cover story, “Sea Level Rise Threatens Waterfront Development.”