If there is a State Agency regulating withdrawals, they probably receive reported withdrawals from the power plants. DMRs contain volume discharged from all pipes in the facility, and when compared to the permit or permit application will correlate to the source of the water and how it was used. Since thermoelectric plants tend to be major water users, data generally are metered and are available from at least two federal agencies, one or more State agencies, from the power utility, and from individual power plants. It generally is considered unnecessary to measure water withdrawals because of the availability of metered data. Gross power generation figures should be obtained, not net generation figures.
Gross power is the total amount of power generated by the plant.
Some of the power generated by the power plant is used to run the plant so that the power available to the grid is net power generated. The net power generated is equal to gross power generated by plant minus the amount of power needed to run the plant. The information from the above sources should be integrated. Unless there are major changes in the plant operations, estimates of water use and return flow can be made from power generation data for future years. This generalized relation should primarily be used to ensure that the data set received from the above agencies are reasonable, and not to estimate the rate of water use, discharge, and evaporation.