Upper Bear Creek Operating Guide

WARNING! Water release schedules can change without notice due to unanticipated weather changes or power system requirements. Large amounts of water could be discharged at any time. Use caution! Obey all posted safety regulations and precautions!  Vital safety information.


What Is an Operating Guide?

Operating guides were designed and developed for every reservoir and are used in making critical decisions regarding the storing and/or releasing of water from dams throughout the entire Tennessee reservoir system. These operating guides are centered on decades of operating experience, including more than 100 years of rain data and seasonal variation.

Factors in determining the storing and/or releasing of water include the following:

  • A reservoir’s size, shape, surface area and storage capability
  • The landscape of the surrounding watershed (Is it widespread and flat as in the western Tennessee Valley or is it mountainous and unyielding as in the eastern Valley?)
  • The average rain and runoff
  • Industrial, agricultural and municipal needs for water

Midnight Elevations

Recorded midnight headwater elevations above the dam are shown on the graph for two years—last year (black line) and this year (red line). Gauges located at the dam record the elevations in feet above mean sea level.

Low Notch

A low notch is a rectangular opening along the top of a spillway that allows a controlled flow of water to pass from the reservoir pool to the downstream riverbed.

Spillway Crest

The spillway crest is a point in elevation where water passes from a reservoir through an overflow section of a dam to the downstream riverbed. Upper Bear Creek spillway crest is at elevation 799.

Comparing Other Reservoir Operating Guides

When comparing reservoir operating guides of other reservoir operating guides, know that tributary reservoir elevations fluctuate significantly throughout the year and those graphs reflect an expansive vertical axis. On the other hand, main-stem reservoir elevations fluctuate very little since those reservoirs have far less storage capacity, so those graphs reveal a much tighter vertical axis.