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Dam & Lake Level Basics

Our lakes provide benefits that are balanced among the individual needs of several communities, including:

  • Municipal water supplies
  • Industrial and power plant water uses
  • Daily release requirements and drought mitigation
  • Wildlife habitat and aquatic environments
  • Recreation (fishing, boating, skiing, docks, etc.)

Each lake directly affects other lakes on the Catawba River system. To manage the level of one lake, Duke Energy must examine the levels and requirements at each of the other lakes in the system and respond accordingly.

Reservoir Level Variability: Lake levels can vary depending on the location on the reservoir. The lake levels reported on this website are measured at our hydro station dams. During high inflow events, water levels (elevations) could be substantially above (e.g., 5 feet or more) the levels recorded at the dam.

reservoir level variability

We move water downstream using the following methods:

Hydro generation (through the turbines)
Hydro generating units serve as Duke Energy's primary means of moving water. Depending on the design, our generating units can usually pass two to four times the average inflow to a lake or reservoir. When heavy rain inflows exceed the normal hydro unit discharge capabilities, alternate methods must be available to pass the excess.

hydro generating unit

A hydro generating unit releases water through a penstock.

Over the top of an open or ungated spillway
The simple, effective design of an open spillway allows large volumes of excess water to move downstream. This method also provides automatic function, requiring no human intervention.

open spillway

When water level is below full pond, it is held behind an open spillway.

water over an open spillway

When water level exceeds full pond, it pours over the spillway.

Through gated spillways (sometimes referred to as "floodgates")
A gated spillway consists of manually operated floodgates. The operation of the floodgates is tested on a routine basis.

water held behind a gated spillway

Water held behind a gated spillway.

water released from a gated spillway

Water can be released from the spillway by lifting the gate.