Tidal Marshes Save Hundreds of Millions of Dollars
Levee Cost/Mile (In Millions) Over 50 Years $14M
Sea level rise caused by global warming is already inflicting damage to developed areas along the San Francisco Bay shoreline. That damage and its associated costs will increase as sea level rise accelerates. The current flood management system is inadequate to maintain sufficient levels of protection. Important public infrastructure, including highways, bridges, roads, rail lines, utilities and airports, will experience increased damage from flooding in the coming decades. In the near term, between now and the second half of the 21st century, the bulk of that damage will be inflicted by storms arriving on higher tides.
Earthen Levee
$12.5M
Tidal Marsh
$12M
Brackish Marsh
Cost per Mile
$10M
$8M $6.29M
$6.69M
$6M
$4M
The conventional and, until now, presumed least costly approach to addressing flood risk has been to increase the height and bulk of $2M levees. (Other more costly alternatives include construction of sea walls and tidal barriers.) Although it has been recognized for many 0 Traditional Levee Tidal Marsh Brackish Marsh years that tidal marshes and associated wetlands provide tangible Earthen Levee Tidal Marsh flood protection benefits, those benefits generally have been Earthen Levee Shoreline Type dismissed during planning and construction of flood protection networks. restoration can be used as an effective flood protection method that An effort is currently underway across the entire San Francisco is far more cost effective than traditional approaches. Second, a new Bay to restore vast tracts of tidal marshes and associated wetlands. marsh restoration paradigm can facilitate marsh survival during However, design of these restoration projects has generally not the current era of sea level rise, thereby protecting important marsh incorporated provisions for long-term sea level rise. In order to functions. fully realize the benefits of the marsh restoration program, new The study clearly finds that nature’s capital is quite tangible and designs must be developed and implemented that can accommodate can be put to much greater benefit than is currently the case. It increasing sea levels. further demonstrates that to continue to rely on old solutions is far This study identifies two strategies that can be employed to more costly to society. It points the way to a powerful tool in the sea accomplish two critical public policy objectives. First, tidal marsh level rise adaptation toolbox. 8