Great Falls Operating Guide
|2014 Observed Midnight Elevations|
|2013 Observed Midnight Elevations|
Observed midnight elevation
Observed midnight elevations are shown for two years: last year and the current year to date. These are the actual elevations of the reservoir immediately upstream of the dam, measured at midnight of each day. The previous night’s elevation is added to the graph by 6 a.m. the next morning.
The line depicts the elevation immediately upstream of the dam which TVA targets throughout the year.
If you compare the operating guides for different reservoirs, please note that the scale for the vertical “Elevation” axis varies. To keep the size of the charts consistent, a larger scale is used for reservoirs that fluctuate significantly; a smaller scale is used for reservoirs that typically fluctuate only a few feet.