• River: Keowee River
• Surface Area: 18,500 Acres
• Shoreline: 300 Miles
• Length: 26 Miles
• Average Depth: 54 Feet
• Maximum Depth: 297 feet
Lake Keowee is a man–made reservoir in the United States in the state of South Carolina shaped somewhat like a Christmas tree. It is notable for having been created to serve the needs of a power utility (Duke Energy) as well as public recreational purposes. It is approximately 26 miles long, 3 miles wide, with an average depth of 54 feet, and a shoreline measured at 300 miles in total, and is approximately 800 feet above sea level. It began in 1971 as a massive demolition and building project, including the construction of two large dams––Keowee Dam and Little River Dam––and covered 18,372 acres of the state. The lake collects or impounds waters from the Keowee River and the Little River and others, and the outflows below the respective dams join to form the Seneca River which flows into the larger Savannah River. Lake water helps to cool Duke Energy's three nuclear reactors located at the Oconee Nuclear Generating Station. In addition, the force of falling water through gravity helps generate hydroelectric power. The Keowee Hydro Station generates 158 megawatts from the lake's outflows. In addition, Lake Keowee has been touted as a recreational destination for fishing, boating, swimming, sailing, kayaking and other watersports, and the lake has been described as having pure and clean water. The name Keowee is a Cherokee name roughly translated as "place of the mullberries." The former Keowee River, which was inundated by Lake Keowee, had been part of the Cherokee Lower Towns region, and Keowee Town had been located on the bank of the Keowee River.
The Keowee dam has two hydroelectric generating units, capable of generating 40 megawatts which is sufficient energy to power approximately 7,000 homes. In addition, a tunnel was built for the purpose of transporting water. The Keowee water transportation tunnel is 800 feet long and 33.5 feet feet wide and contains a maximum of 5,300,000 US gallons with an average flow rate of 1,000 cubic feet per second.
To cool the nuclear reactors, a structure called the Oconee skimmer wall was built which separates the plant's inlet canal from the lake itself. The effect of the skimmer is to fetch cool lake water from a depth of 150 feet which serves as a middle point in the lake's depth—it is sufficiently deep to be able to extract water during a drought or prolonged dry spell in which lake levels drop, and it is not too deep where inlet valves may become blocked with mud or other particulate matter. Duke Energy closed the gates of the Keowee dam on April 2, 1970, to being the final phase of building up the water or what engineers refer to as impounding the lake, to reach an ultimate lake depth of 150 feet. The Keowee hydro station began commercial operation on April 17, 1971.
Duke Energy's Oconee Nuclear Station is about 8 miles each way from the towns of Salem to the north and Seneca to the south. According to one estimate, it has a generating capacity of 2.6 million kilowatts of power, which is enough to power 1.9 million homes. In 2011, the United States Nuclear Regulatory Commission renewed the site's license for an additional 20 years of service.
Since Duke Energy built the lake and uses it regularly for power generation and cooling, it exerts considerable authority towards its operation. It has management responsibility for not just the lake, but for the shoreline around the lake including docks and walls, and is responsible for the land around the lake up to a specific elevation. While it has significant authority over the lake area, the Federal Energy Regulatory Commission "looks over its shoulder" in such aspects as whether the lake is accessible by the public. Duke Energy is also Oconee county's largest taxpayer. Builders and developers and others often must have written permission from the energy utility before embarking on any significant changes around the lake. At the same time, Duke Energy cooperates with state and federal authorities to manage the area; for example, in the summer of 2011, energy officials conferred with the United States Army Corps of Engineers regarding matters such as lake levels and making changes to nuclear station pumps for added flexibility. In addition, the utility has sponsored clean-up drives to keep the lake free of litter and pollution, and has commissioned studies to monitor "recreation pressures on the lake".
Residents who have bought homes along the lake or nearby formed an advocacy group named the Friends Of Lake Keowee Society or abbreviated as FOLKS. It was established in 1993 to represent the interests of lake residents in terms of environmental and recreational issues, and have taken such initiatives as monitoring the lake's water quality and watershed. An "Island Keeper Program" is an effort to reduce litter. The advocacy group has brought pressure to block proposed developments; for example, developers seeking to build a multi-use facility in 2011 including a restaurant, store, lodge and fueling station, had to face FOLKS members in a public hearing to get community input. The group is concerned with the lake area becoming over–developed, with too many houses or developments, which may interfere with the overall beauty of the lake. There have been concerns about overcrowding, light pollution, noise pollution, and stormwater runoff. Large-scale developments tend to cause greater concern. One estimate by the advocacy group was that there were at least 80 land parcels on or around the lake which had at least 10 acres each.
County authorities have exerted influence on what happens in and around the lake. In one instance, authorities raised concerns about a planned 12–story highrise condominiums around the lake on the basis that it might change the lake's "skyline".