To make signicant progress in minimizing the occurrence of harmful algal blooms (HABs) and the impacts of HABs on drinking water, regulatory approaches are needed. Currently, there are no federal regulations or US guidelines for cyanobacteria or their toxins in both recreational and drinking water. However, a number of existing water quality regulations, at both the state and federal level, do provide means to manage and/ or control HABs and their related toxins. In this chapter, regulations for HABs and HAB toxins in drinking water at the state, federal, and international levels are discussed. Other relevant regulations, such as the Harmful Algal Bloom and Hypoxia Research and Control Act, regulations managing HABs in recreational waters, as well as current attempts at both the state and federal levels to establish nutrient criteria, are examined.