I was recently working on a study in the Saw Mill Creek marshes. This site is characterized by large patches of Phragmites adjacent to extensive Spartina alterniflora, the grass that is typically found in east coast salt marshes. I was surprised to find large Spartina plants growing amidst the Phragmites. Salt marsh vegetation is controlled by water flow, and Spartina is usually found at lower elevation, higher salinity locations. Phragmites prefers drier, less salty conditions. Finding the Spartina in a Phragmites stand, I began to consider the effects of sea level rise in the Hackensack Meadowlands.

The response of coastal wetlands to rising sea level is an urgent problem facing residents living along the eastern coast of the U.S. We are aware of the effort and money involved in maintaining the sand beaches in New Jersey's shore communities, but little is being said or done to plan for the potential effects of rising sea level in the Meadowlands.

Under natural conditions salt marshes are able to respond to sea level rise. Vegetation colonizes new sediment deposits that are carried into the marsh on the tide or down from higher land by rivers. As the new vegetation decays, a higher marsh surface is formed from the mixture of vegetation remnants and sediment particles. This process allows the salt marsh to accrete vertically, thus keeping up with sea level rise, and the marsh can continue to serve as a buffer between tidal and upland ecosystems. Under natural conditions, if sea level is rising faster than a marsh can accrete vertically, the marsh moves inland and high marsh converts to low marsh as in the figure below.

Today the Hackensack Meadowlands are not able to respond to sea level rise like a natural system. Before the dam in Oradell was built in 1922, sediment was carried downriver where it was deposited in the wetlands, helping the marsh keep pace with rising sea level. However, because the hydrology and sediment flows have been changed by the dam, much of the historical sediment load is now deposited further upriver rather than in the Meadowlands. Additionally, development along the river edge blocks movement of the marsh inland and there is little high marsh left to convert to new low marsh.

In spite of projections by various government agencies that rising sea levels will be a major threat to our coastal communities, development projects continue to be approved, making a bad situation worse. An example of this lack of foresight is the proposed fate of the Empire Tract. The hydrology within this part of the Meadowlands has been altered, so the largest contiguous marsh surface remaining in the Meadowlands is currently covered with Phragmites. However, this marsh would serve as an upland buffer as sea level rises, potentially becoming a Spartina low marsh.

Although the Army Corps of Engineers is battling the problems of sea level rise in the Southern U.S., this problem did not appear to be a consideration in their recently released EIS in support of the Meadowland Mills project. When government policies fail to take into account scientifically relevant information, the local community is forced to live with the consequences of poor planning. This is currently happening in situations as diverse as raging western wildfires and devastating floods that are destroying millions of dollars of private property.

The Hackensack Meadowland marshes can help protect Hackensack River communities from the future effects of a rising sea level. Our local government representatives and agencies must find a way to preserve these last remaining wetlands.