Potential ground-water level changes in the Mississippi River alluvial aquifer in response to proposed navigation improvements on the Yazoo River in Mississippi

A proposed navigation project on the Yazoo River between Vicksburg and Greenwood, Mississippi, will increase minimum river stages by more than 19 feet at the site of the proposed lock and dam near Vicksburg, and will decrease minimum river stages by 2 to 7 feet in much of the upper reach of the river. Water-level data for 65 observation wells in the alluvial aquifer in the vicinity of the proposed project indicate that post-project minimum ground-water levels in wells very near the river will range from more than 19 feet higher than pre-project minimum levels near Vicksburg to about 7 feet lower than pre-project levels at Greenwood. Post-project ground-water levels will generally be between 15 and 25 feet below land surface during the dry season but will be at or near land surface during the wet season. The change in ground-water levels will decrease with distance from the river but may extend as far as the Bluff Hills to the east and the auxiliary channel or other major drainage features to the west. In the upper reach of the river the decrease in ground-water levels may extend beyond the auxiliary channel to the areas of large ground-water withdrawals several miles to the west of the river. (USGS)