In most situations a dam can be properly configured by defining outlet structures such as spillways, uncontrolled outlets, etc. The total outflow from the reservoir can be calculated automatically using the physical properties entered for each of the included structures. However, some reservoirs may have an additional release beyond what is represented by the various physical structures. In many cases this additional release is a schedule of managed releases achieved by operating spillway gates.
Currently the only method for making an additional release is the Gage Release method. The modeler can specify the additional releases based on a gage reading (time series of discharge). This release is subtracted from the reservoir pool during the iterative calculation, in order to include the controlled releases the releases from the other outlet structures are determined.