Natural and Man-made Water Bodies

Water bodies consist of both man-made and natural areas that retain surface water at least part of the year.

Around most streams and rivers, especially in the Flatwoods region in Southwest Georgia, thare are areas where excess rainfall collects. These widened floodplains include ponds formed as meandering rivers changed courses, sometimes leaving ponds and lakes that retain water year round. But much of the flood plain is made of wetland areas that have water only during high rainfall periods and when streams overflow their banks. Natural wetlands and waterbodies are essential to the health of ther associated surface streams improving water quality and accepting flood flows. During dry periods these areas supply water back to the streams. Natural ponds and wetlands may also have connections with underlying shallow aquifers, resupplying them or acting as drains for those aquifers.
Man-made ponds, lagoons, and reservoirs serve many purposes. Most are formed by holding back water behind earthen or reinforced dams. The smallest ponds may be dug out depressions that are refilled by seepage from surrounding soil or shallow groundwater. More commonly ponds are created by creating dams as barriers across natural drainage ways. Rainfall runoff from a "catchment" area flows to and down these natural drainage ways filling the area behind the dam. To protect these dams from being topped over and weakened by the flowing runoff, most dams have pipe spillways to handle normal flow and controlled over-flow or emergency spillways for storm flow.

When larger and more dependable supplies of water are needed, dams may be built across flowing streams or even large rivers. These tend to change the natural flow of the streams, and land that lies under the newly flooded areas may change the natural and human uses of the that land. Changes can be minimized through careful planning and management, but all man-made changes involve tradeoffs. Large dams require careful design, construction and management. Federal agencies regulate the largest of these structures, particularly when the dam would affect downstream navigation.

An alternative for dependable water supply reservoirs is off-stream reservoirs. These may be built in the flood plains, but the stream or river flow is less affected, particularly during flood periods. Off-stream reservoirs are refilled by controlled upstream inlets or by pumping from the stream. These supplies as less affected by the changes in seasonal flow and water quality. Inlets may be closed during flooding, preventing sediment-laden runoff from entering the reservoir.

Ponds and reservoir uses vary widely. Most add value to the property that is adjacent to the water body. Most Georgians appreciate the aesthetic value they add to the landscape. Even small ponds can supply recreation including fishing, swimming, and boating. Fire protection is improved, especially in rural and suburban areas that lack large pressurized water systems.

In addition to these values placed on water in filled ponds and reservoirs, water is removed from some reservoirs for in-stream use. The large reservoirs can be used to sustain flow during droughts when flow in rivers may be lower than needed for navigation. Releases can refill downstream reservoirs, or even improving flows for fish and other wildlife. Most of these releases capture part of the energy from the stored water as electricity generated during releases.

Water can also be removed from the reservoirs for the wide variety of off stream uses. Municipal drinking and commercial water supplies, industrial withdrawals, athletic turf areas and landscape watering are a few of these uses. In farming areas, landowners build small to moderate reservoirs on their property to supply water for their livestock or to irrigate their crops. All of these off-stream uses remove at least a part of the water from the region's stream system, potentially affecting annual flow. In balance, much of the water that is withdrawn would have travelled downstream to the Gulf of Mexico or the Atlantic Ocean by the time that the withdrawal is made from the reservoir.

Hook, J.E. and S. Conger. Roles of Farm Ponds and Potential Impacts on Streams in the Coastal Plain of GA . Southeast Environmental Flows Conference. October 28, 2008, Athens, Ga (10mb download)

Hook, J.E. et al. Revisiting farm ponds for irrigation water supply in the Southeast US . Irrigation Association Proceedings Nov, 2, 2008, Anaheim, CA;  Presentation (10mb download)