Sources of Reservoir and Pond Data

New aerial imagery as seen above allows detailed identification of water bodies like the ponds seen above. We have added USGS mapped streams and DOT mapped ponds as they outlined them. Note that even the more extensively mapped DOT data has not mapped every pond like the one among the pivots. Some new ponds are built every year, and old ones are reconfigured or rebuilt to improve them. Keeping up with ongoing changes is possible now with aerial imagery released every year by federal government.

Pond imagery and data noted on these pages was derrived from the two sources described below.
Some water body data has come from USGS efforts to map streams and other flowing water along with associated wetlands and reservoirs that can affect that flow. USGS uses a combination of techniques including analysis of scanned topographic maps first prepared from surveys many years ago, new airplane-based aerial imagery, and topographic mapping of those images. With these data they are able to note stream channels and direction of flow. Periodic dry-season, field verification is used to note perennial vs ephemeral streams, although even perennial stream channels may dry up in drought years. Aerial imagery provides location of ponds and reservoirs built in or near these stream channels.

USGS released a version of the stream flow and water body data as a GIS layer in 2006. This National Hydrographic Data (NHD+) set is the most comprehensive data on streams in the Southeast. The image below shows the mapped streams and associated riparian wetlands and reservoirs. The view is a portion of Tift County in the Coastal Plain of Georgia. Note that many of the ponds appear at the terminus to small stream channels. However seasonal stream and runoff channels exist beyond and between the mapped stream channels.





The Georgia Department of Transportation has also mapped streams and ponds as they designed roads and highways. Roadways must be built high enough to resist most flooding, and culverts must be sized to handle stream flow. Dam failures can affect downstream road structures as well. Following passage of the Safe Dams Act, the DOT began systematic mapping of all ponds. Built on their county road maps, the water bodies they mapped do not always align perfectly with USGS shapes for the ponds. However, the DOT maps noted many more ponds, as they mapped even the modest landscape ponds (see additional ponds on the same map, below). They did not map marshes and wetlands as extensively. Our maps use wetlands and marshes from the USGS and ponds from the DOT.