“Spring usually means several things—the leaves get green, birds begin to sing and so on,” says Tom Barnett, senior manager, TVA River Forecast Center. “It’s also the time reservoirs begin to fill to summer levels.”
At the time of its inception in 1933, TVA (Tennessee Valley Authority) had a significant task at hand – controlling the fluctuating rainfall patterns that frequently result in cycles of drought and flooding and plagued the Tennessee Valley. The uncontrolled rivers were responsible for washing away the fertile topsoil, causing extensive erosion and hindering farmers’ crop yields. The risk of flood damage also escalated as towns and cities were established along the riverbanks. To mitigate the risk of flooding, TVA developed a sophisticated system of dams and reservoirs. As time passed, additional benefits of the river system became evident, including creating a navigable waterway, generating hydroelectric power, a reliable and clean water supply, and plentiful water-based recreational activities.
Initially, TVA’s primary goal was to control flooding and produce electricity by developing a network of dams and reservoirs to subdue the unruly Tennessee River. Today, the agency’s responsibilities extend beyond these initial tasks, including maintaining water quality, supporting navigation, and supplying water for power generation, and recreational, agricultural, and industrial use. During the summer months, TVA prioritizes filling reservoirs for recreational purposes which majorly benefits East Tennessee lake homes and controls water levels as needed.
Flood Control
TVA has achieved a remarkable feat by skillfully designing and administering the Tennessee River watershed and its network of dams, resulting in the virtual elimination of flooding in the Valley. This is no small accomplishment considering that before the establishment of TVA, flooding was a constant menace that caused significant damage to property and people’s livelihoods. TVA recognized the severity of the situation and made it a priority to control floods. To achieve this objective, TVA developed an innovative system of dams and reservoirs that regulate water levels by varying them at different times of the year.
Ready for Rain
The mechanism works as follows: In anticipation of the rainy season, TVA lowers the flood-storage reservoirs’ water levels in “drawdowns”. to make room for the runoff that results from winter storms. During a storm, TVA controls the water flow by decreasing the amount released from the dams in areas where it is raining. When the rain stops and the risk of flooding has subsided, TVA gradually releases the water to prepare for the next storm.
Whereas TVA plays an active role in the winter drawdown, it relies on nature for the rainfall and runoff necessary to complete the spring fill. What it can do is wait, watch, and adjust operations to reflect meteorological circumstances. During the summer, when the risk of flooding is low, TVA maintains higher lake levels to support recreational activities.
Navigation
Unlike the tributaries, main-river reservoirs are designed to meet navigation requirements and, therefore, do not fluctuate as much. Their drawdowns are staggered from July to the end of the year to ensure optimal use of the released water.
The Tennessee River is the main-river reservoir home to thirteen locks that span its 652-mile length, allowing for the passage of thousands of barges each year. These barges transport approximately 40-50 million tons of goods and help save consumers an estimated $400-$500 million in transportation costs.
For this reason, the lakes that create and support the Tennessee River including Watts Bar Lake, Tellico Lake, and Ft. Loudoun Lake lose minimal water of only 4-6 feet in the winter months to support year-round navigation. The seasonal lakes that lose 20-60 feet of water in winter months are Norris Lake, Douglas Lake, and Cherokee Lake. The specific lake and water level in winter can certainly affect the value of lake homes and a big factor in the best lake communities being located on year-round waterways like Tellico Lake.
Excerpts from TVA
Posted by Oceana Richards, Lakefront Living Realty, TN