Action Stage: The stage at which some sort of action is taken for a point along the river. Action Stage is different for all points depending on the community's needs - it may be flooding of secondary roads or just a "heads up" that the river is rising. Action Stage is determined by the National Weather Service. Sometimes used interchangeably with Bank Full Stage.
Bank Full Stage: The stage at which a river will not overflow its river banks or cause any significant damage within the river reach. Bank Full Stage is determined by the National Weather Service. Sometimes used interchangeably with action stage.
Cubic Feet per Second (cfs): A measure of streamflow. One CFS is equal to about 450 gallons per minute.
Elevation: The height of water in a lake or reservoir above mean sea level.
Flash Flood: A flood which follows within a few hours of heavy or excessive rainfall.
Flash Flood Warning: Flash flooding has been reported or is imminent – take necessary precautions.
Flash Flood Watch: Flash flooding is possible within the designated watch area – be alert.
Floodgates: Solid gates that are opened as needed to release floodwaters.
Flood Stage: The stage at which roads or buildings begin to get affected. Flood Stage is determined by the National Weather Service.
Hydrogeneration: Using water that is passed through a dam to generate electrical power with a turbine.
Mean Sea Level (msl): The elevation of the ocean halfway between high and low tide. Elevations are measured in feet above mean sea level as a point of reference.
Operating Range: The elevations between which the lakes are operated during normal conditions. Lake levels can fluctuate outside of these ranges at times.
Pass-Through Lakes: Lakes designed to allow water to pass through as opposed to being stored. Pass-through lakes do not have a constant level. Lakes Inks, LBJ, Marble Falls and Austin are "pass-through" lakes.
Spillway: The area of a dam that is designed to allow water to flow freely over it.
Stage: The height of water flowing in a river above a nearby reference point, for example, the height of the water above the river bed.