Many eutrophic lakes respond slowly following nutrient diversion because of long water retention times, and the recycling of phosphorus from sediments and other internal sources. Treatment of lakes with aluminum sulfate and/or sodium aluminate is a successful method for removing phosphorus from the water column. Twenty-eight lake projects treated with aluminum salts are reviewed and summarized. The technique is successful when sufficient doses of aluminum are applied, however, a few undesirable side effects such as reduced planktonic micro-crustacea species diversity an increases in rooted plant biomass may occur. Two methods for determining aluminum sulfate doses are compared. Maximum dose, is defined as that dose which reduces pH to 6, a pH favorable for forming insoluble aluminum hydroxide and for assuring that dissolved aluminum remains below potentially toxic concentrations. Lake dosage can be easily determined prior to application by titrating several lake water samples of varying alkalinity with aluminum sulfate, determining maximum dose for each sample, and establishing a relationship between alkalinity and dose.

"February 1981." Includes bibliographical references (pages 37-41).