THE IMPACTS OF HIGHWAY CONSTRUCTION IN THE OCMULGEE OLD FIELDS RESERVE

The construction of Interstate-16 near Macon, Georgia was completed during the mid-1970s. Much of this construction involved placement of the highway corridor on a raised roadbed passing through the historically significant riparian wetlands of the Ocmulgee River. This construction has significantly altered the hydrology of the area because minimal bridging was included in the design plan for the highway. The ‘Ocmulgee Old Fields’ is a fifteen square mile tract of upland terrestrial and bottomland hardwood forest that has been recognized as the cradle of the Muscogee Creek Nation. With a documented history of human habitation dating back at least 12,000 years, this land is partially protected by the National Park Service as the Ocmulgee National Monument (ONM) while other areas have been recently identified as Traditional Cultural Properties (TCP) of the Muscogee Creek Nation.A current plan to construct another transportation corridor, the Fall Line Freeway, that would provide for direct transportation between the cities of Columbus, Macon, and Augusta, Georgia, may pass through the riparian wetlands along a tract of privately owned land within the confines of the Ocmulgee Old Fields. The Fall Line Freeway would also encroach on the second deepest peat soil deposit in the state of Georgia (depth=19 ft).To predict the impact of new highway construction on this region, we studied the effect that Interstate-16 has had on the hydrology and habitat structure of the bottomland hardwood forest. A general survey indicates that the minimal bridging on I-16 prevents surface waters from their natural flow toward the river. The crossing of the I-16 roadbed with a pre-existing railroad bed has impounded waters on the southeastern border of the Ocmulgee National Monument. Impoundment has transformed this zone from a forested wetland plant community with rich organic soils to an open aquatic wetland with emergent and floating vegetation. Also, waters naturally flowing toward the river in a southwesterly direction are channelized and unable to flow across a tract of land between the Interstate and the parallel Ocmulgee River. Wetland site assessments were performed along three transects each beginning at the base of Interstate-16 and running perpendicular from the highway toward the Ocmulgee River. At 100 foot intervals, a site assessment was performed including a full characterization of plant community structure (trees, shrubs, vines, and ground cover) and the hydrology and soil type were identified.The findings indicated that between the highway and the river that any random or non-random event that removed forest canopy had a more significant impact on wetland community structure and function than did proximity to the highway. Finally, two peat cores were collected in the northeast corner of the study site (north of I-16, east of ONM). The cores were extruded and subsamples were dated using 14C-dating techniques. With soils dating back to nearly 9,000 yrs BP, assays for corn pollen, charcoal fragments, and silt content demonstrate that these peat deposits are significant to revealing the natural and cultural history of the Ocmulgee Old Fields Reserve. These studies provide a foundation of scientific evidence that will establish the natural and cultural “value” of this land and will aid in the assessment of the impacts of Fall Line Freeway construction through the Ocmulgee Old Fields Reserve.