Anthropogenic activity is responsible for changing environmental conditions in many environments, including nutrient over-enrichment in lakes and coastal waters, and elevated temperatures and carbon dioxide concentrations in the atmosphere and water. Due to these changes, many lakes have become increasingly stratified and eutrophic. These factors create a perfect environment for the proliferation of cyanobacterial harmful algal blooms (cyanoHABs) in freshwater systems. Lake Anna, a reservoir that was originally created to provide cooling water to a local nuclear power plant, also serves as a recreational site for the surrounding area. The lake has experienced potentially toxigenic cyanoHABs almost annually since 2018, typically during the summer and early fall months. Potentially toxigenic cyanoHABs are species that have the ability to produce toxins that can have adverse effects on humans, terrestrial and aquatic animals. This project aims to explore the factors essential to initiation and proliferation of these blooms, as well as the controls on toxin production. This project is being conducted in partnership with USGS and entails an extensive monitoring effort of water quality parameters (pH, temperature, dissolved oxygen, and chlorophyll a), particulate nitrogen and carbon concentrations, nutrient concentrations (dissolved organic and inorganic carbon and nitrogen), and the microbial uptake of nitrogen, including dinitrogen gas, a source of nitrogen available to many cyanobacteria. In conjunction with the sampling efforts a full characterization of algal communities is being conducted to understand the succession of the dominant species throughout the year and any related toxins. Understanding how cyanoHABs are using different inorganic compounds throughout the year can give insights into sources of nutrients and insights regarding mitigation to prevent the growth and proliferation of these blooms.