Benefits attributable to low-flow regulation from the Allegheny Reservoir are estimated and discussed. Tangible benefits are those which are capable of economic evaluation. Intangible benefits are those not capable of economic evaluation, such as recreation, public health, and aesthetic improvements. The Allegheny and Ohio Rivers are used to supply water both for municipal and industrial consumption. Low flow augmentation will reduce the hardness and acidity and water temperatures resulting in more efficient water use by industry. The decrease in hardness and acidity will reduce the corrosion damage to navigation interests and will reduce the costs of sewage treatment for Pittsburgh and Cincinnati. Intangible benefits to public water supplies result primarily from the maintenance of more uniform water. Augmentation will also help to mitigate taste and odor problems and enhance the Allegheny River for recreational uses.