Utilities were confronted by a major cooling water treatment challenge in the 1970' s. Central station power generation units were built with man made lakes for condenser cooling in the previous decades. These lakes concentrated with time creating a calcium carbonate scale problem in the once through cooled surface condensers and auxiliary cooling systems. In some cases, the problem was further aggravated and accelerated by the addition of multiple power generation units to the lakes, well beyond the original design specifications. Condenser scale caused increased back pressure in the turbines, increased heat rate, and in many cases, deration. Traditional once through cooling water scale treatment approaches could not economically control the scale. Cost for treatment using the one(l) to nine(9) mg/L dosage rates for polyphosphate based scale control agents common at the time for once through scale control, were higher than the cost of increased fuel consumption and lost production capability. This paper describes the evolution and history of an economical treatment approach for high volume utility once through cooling systems based upon polymers and phosphonates. The theoretical and practical application of dosage optimization models used to modulate the inhibitor dosages is discussed in detail. The system described, or derivatives of it, are commonly used today for high volume utility once through scale control.