New study indicates significant likely impact of further development and coastal protection on wetlands

[Thomas Ruppert]

Here is a summary of a new paper recently published by James Titus and coauthors on the impact continuing and increased coastal development and protection will have wetland migration in the face of sea level rise. Makes for interesting reading as they argue that the federal government is violating the Clean Water Act by allowing extensive armoring to take place.

State and local governments are planning the development of most land vulnerable to rising sea level along the Atlantic coast, according to a new article in Environmental Research Letters. The authors collaborated with 131 local governments to create sea level rise planning maps that divide coastal lowlands into four categories based on the likelihood of shore protection as sea level rises: developed, intermediate (future development), undeveloped, and conservation. Approximately 60% of the dry land within one meter above high water is either developed or expected to become developed. Shore protection is likely for these lands, which will block the inland migration of coastal wetlands and expose people to coastal hazards. Only 10% of these lowlands are in conservation lands where natural shore processes will be allowed to operate. Development is not immediately expected for the remaining lands, but even here the landward migration of wetlands is not guaranteed, because there generally are no rules preventing the land from eventually being developed, and dikes are often built to protection valuable farmland.

The authors draw two conclusions from their mapping. First, there is likely to be significant cumulative impact from shore protection, given that 60% of the wetland shores will have structures that block their landward migration. Because most permits for shore protection structures are issued under a nationwide permit, and nationwide permits are allowed by the Clean Water Act only if they do not have a significant cumulative impact, it follows that the existing policy violates the Clean Water Act, and a new regulatory regime will be needed. Second, policies are needed to slow or halt development in the areas where wetland migration is still a reasonable possibility. Much of this undeveloped land is the Carolinas and Georgia.

The paper was written by James G. Titus of the US Environmental Protection Agency, based on a set of state-specific studies previously funded by EPA. The key investigators of the various studies joined the new paper as coauthors. Regional planning councils provided the analysis for Florida, Georgia, and Pennsylvania. The Seagrant programs of Massachusetts, New York, and North Carolina provided the analysis for those states, Texas Seagrant has prepared a similar study (which was omitted from the new article which focuses on the Atlantic Coast), and the New Jersey program contributed to a companion assessment. Each of these Seagrant programs should explain the state-specific findings on their own web sites. State-specific findings and GIS data are available on the project web site.