Potential Consequences of Saltwater Intrusion Associated with Hurricanes Katrina and Rita By Gregory D. Steyer, Brian C. Perez, Sarai Piazza, and Glenn Suir Hurricanes Katrina and Rita pushed salt water from the Gulf of Mexico well inland into freshwater marsh communities in coastal Louisiana. This paper describes the spatial extent of saltwater intrusion and provides an initial assessment of impacts (salt stress) to coastal marsh vegetation communities. Introduction Katrina and Rita, two storms of exceptionally large size and strength, struck the northern Gulf of Mexico coast within a 1-month period in late summer of 2005 near the State borders of Louisiana- Mississippi and Louisiana-Texas, respectively. Catastrophic winds and waves had a direct and devastating effect on human lives, properties, and various infrastructures. Furthermore, the impacts of these two storms are expected to have major effects on coastal natural resources. Many conditions, such as salinity and storm surge, are transient in that their presence may be lost rather quickly unless rapid-response sampling takes place. While direct evidence of transient conditions may be temporary, they can be a catalyst for factors which may have long-term effects on the ecosystem. Salinity is one of the transitory elements that are critical in understanding the long-term consequences of these storms on habitat change and coastal restoration. Coastal saltwater and freshwater marshes were flooded with storm surge for weeks in some places, which increased the time for salt to diffuse into the pore water (i.e., interstitial water in the soil). Over time, porewater salinity should decline as it diffuses into overlying flood waters, provided that fresh water is available for flushing, either by precipitation or by mechanical introduction (e.g., freshwater diversions). If fresh water is not introduced, porewater salinity levels may