Bogus Water Use Claims

"Fossil power plants in eight western states consume 650 million gallons of water daily, the same volume needed to serve the requirements of six cities the size of Denver", according to a report cited by a newspaper.
This is grossly misleading. These power plants may withdraw 650 million gallons but return around 98% of the water to the rivers, lakes etc. from which the water was drawn. Only some 12 million gallons (not 650) are actually consumed and this is mostly due to evaporation.
A modern 1000-MW fossil-fuel plant uses about 570,000 gal/min. of circulating water and needs makeup for evaporation of about 7,500 gal/min. Blowdown is normally 20 percent and drift is 2 to 2.5 % of the evaporation loss. (Data taken from Powerplant Technology by M. M. El-Wakil, McGraw-Hill)
Obviously actual usage will vary between power plants but the amount of water actually consumed is very small.
A power plant uses water primarily to cool the left over steam after the steam has passed through the turbines so that the resulting condensate can be returned to the system as boiler feedwater. (See note)
The water used to cool the left over steam is drawn from the river, lake etc. and pumped through a condenser to remove the heat from the left over steam. This cooling water is then returned to the river or lake after it is itself cooled in cooling towers by evaporation. The major loss of water is through evaporation in the cooling towers. Virtually all of the water would be returned from whence it was drawn if it wasn’t necessary to cool the water before returning it to the river, lake etc. so that the water temperature at the point of discharge is approximately the same as at the intake.
The eight state region covered by the news report stretches from Montana to Arizona and New Mexico. Water rights in the West differ from those in the East so that water becomes a more valuable commodity where individuals, municipalities and corporations have specific rights as to the amount of water they can draw from rivers etc. and the conditions that must exist (e.g., stream flow) for them to exercise those rights.
In normal years the only states that consume more water than is replaced through rain are Arizona and New Mexico. The other states in this region normally use only 30% of their renewable water supply. The recent drought has produced water shortages in these states making water a political issue.
Providing misleading information to the public and legislators about the amount of water used by power plants distorts the argument concerning the most efficient way to generate electricity. In this instance, the information provided to the news papers came from a group touting wind power.
Water consumption by power plants East of the Mississippi and in the Northwest is inconsequential as these areas use less than 10% of their renewable water supply.
Note: The water in the boiler is converted to superheated steam that is used to drive the turbines. Left over steam is then cooled in a condenser to form condensate that is returned to the boiler to repeat the cycle. This is a closed loop system where the water is specially treated and kept pure to prevent damage to the boiler tubes and turbine blades. The left over steam passes over the tubes of the condenser while the cooling water passes through the tubes.