This publication, produced by the Pennsylvania Cooperative Extension Service, is a non-technical guide to chemical control of aquatic vegetation. The purpose of this circular is to aid the land owner or manager in managing ponds, streams, and other water bodies for desired uses by managing the vegetation in, on, and around the water. Among the topics discussed are the growth and various types of algae; growth and types of flowering aquatic plants; the effects of the environment on growth; the contributions of aquatic plants to the environment; pollution associated with aquatic plant growth; and management and control of aquatic plants, including mechanical, environmental, and chemical controls. The chemical controls section briefly discusses treatments for various plant types and the possible effects of those treatments as well as dosage calculations, equipment, and application techniques. A short summary and a card showing various aquatic plants with recommended herbicide names are also included. The last half of the publication is a catalog of common aquatic plants. (MR)