Jacksonville Harbor Crosscurrents: Planning Options to Provide a Beneficial Use of Dredged Material Opportunity

One of the most difficult areas of Jacksonville Harbor, Florida, for navigation occurs at the intersection of the St. Johns River (flowing east and west) with the Intracoastal Waterway (flowing north and south), also known as Mile Point. In the vicinity of this intersection, unpredictable crosscurrents occur at various stages of tide which have forced restrictions on inbound merchant vessels. Another significant problem occurring in the Mile Point area involves severe shoreline erosion along the northern banks of the St. Johns River and at Marsh Island along the southern banks of the St. Johns River, in the vicinity of the intersection with the Intracoastal Waterway. Erosion has caused loss of land to private homeowners on the north bank of the St. Johns River and a large breach in Great Marsh Island, on the south bank of the St. Johns, which has caused loss of marsh habitat at Great Marsh Island and shoaling in Chicopit Bay. To address these problems the Jacksonville Port Authority (JAXPORT) obtained a Congressional study authorization to request the U.S. Army Corps of Engineers to evaluate the feasibility of improving navigation and reducing erosion in the Mile Point area of Jacksonville Harbor. The authorization allowed the Jacksonville District of the U.S. Army Corps of Engineers to evaluate measures to reduce or redirect the difficult crosscurrents and to enable the St. Johns Bar Pilots to consider removing restrictions on deep draft navigation traffic. This paper will discuss the history of the problem and the potential navigation solutions proposed, including the tentatively selected plan which beneficially uses dredged material to exceed the required amount of environmental mitigation by restoring historically lost marsh habit. The beneficial use of dredged material for marsh restoration also results in the least cost option for disposal.