Inputs and Selected Outputs Used to Investigate Drivers of Harmful Algal Blooms in Lake Anna, Virginia, 2023 - 2024

Data provided in this release support the Scientific Investigation Report titled "Investigation of Drivers and Sources of Potential Harmful Algal Blooms in Lake Anna, Virginia, 2023-24". This report identified factors and sources leading to Harmful Algal Bloom (HAB) initiation, persistence, and decline in Lake Anna, Virginia. Discrete measurements of Suspended Sediment (SS), Total Nitrogen (TN), and Total Phosphorus (TP) concentration were used in conjunction with continuous water-quality and quantity monitoring stations on two primary feeder tributaries of Lake Anna, Pamunkey Creek at RT 651 Near Lahore, VA (USGS-01670200) and N Anna River at RT 669 NR Monrovia, VA (USGS-016701405), to estimate loads of SS, TN, and TP from June 2023 through December 2024. 15-minute unit-value estimates were calculated using a regression model approach with basic water-quality parameters such as water temperature, turbidity and specific conductance as surrogate variables. Surrogate inputs, model calibration, coefficients, and summary statistics are provided for each model. This data release also contains cyanotoxin concentrations and algal community composition collected between May 2023 and December 2024 at three continuous water-quality monitoring stations on the lake (USGS-01670209, USGS-01670144 and USGS-016702576) and three near-shore transects. Each transect location represents one dominant land-use type for the scope of the project: agricultural, residential, and forested. Time series of continuous wave action were collected at the three lake monitoring stations to assess resuspension of sediment and nutrients. A map of the study area and monitoring locations are also provided.