The upper reaches of the public side of Lake Anna have experienced harmful algae blooms (HABs) and associated recreational advisories since 2018 and there are no environmental indicators that the problem will correct itself naturally.
HABs degrade water quality, produce toxins that are a risk to humans, pets, and wildlife, and have negative impacts on recreation, property values, and the local economy. Legacy nutrients in the lake sediment and concentrated inflows of phosphorus are a key driver of HABs in Lake Anna. Phosphorus is well understood through decades of research as the primary source of HABs in most freshwater lakes.
The Lake Anna Advisory Committee (LAAC) has spearheaded a $903,500 phosphorus mitigation project to start addressing phosphorus issues in the upper part of the reservoir.
EutroPHIX, a division of SePRO Corporation, and Clean Streams Rivers and Lakes (CSRL) were selected through a competitive process to undertake this project. The EutroPHIX project scope includes the application of phosphorus inactivating products both directly to the North Anna tributary of Lake Anna, as well as to the North Anna River upstream of the lake to mitigate ongoing phosphorus inputs from the watershed.
The CSRL project scope includes the application of phosphorus inactivating products to the Terry’s Run tributary of Lake Anna and the use of innovative, beneficial bacteria “bioreactors” to grow and sustain bacteria that compete with the cyanobacteria for nutrients and other sources of energy.
The long-term goal of the LAAC project is to improve water quality in Lake Anna and to mitigate excess phosphorus in the upper lake. The project’s funding was secured through a Virginia General Assembly FY24 appropriation that went to the Department of Conservation and Recreation (DCR) and was then transferred to Louisa County for execution by LAAC. We are currently completing Phase 1 of the multi-year restoration plan for the northern end of Lake Anna.
The active ingredients of EutroPHIX’s products are lanthanum and rare earth minerals that rapidly and permanently bind phosphorus from water and sediment.
The active ingredient used by CSRL is a Calcium Silicate-based granular product and the application of beneficial bacteria directly to the water. The products have a wide margin of safety for aquatic organisms, fish, birds, mammals, and humans, and the treatments have been reviewed and approved by Dominion Energy.
The active ingredients used by both contractors have excellent phosphorus binding capabilities but the process of binding dissolved phosphorus can take 90-120 days to be fully achieved after application.
The data clearly show that the applications in both the North Anna River and Terry’s Run are working and they are having positive impacts on Lake Anna water quality but patience is required as it will take several years to achieve the excess phosphorus reductions needed to put the lake back in balance.
The LAAC monitored the upper lake throughout the year to determine the amount of improvement in water quality and effectiveness of the treatments. In addition, the upper lake continued to be monitored by the Virginia Department of Environmental Quality (DEQ) and the Lake Anna Civic Association (LACA) and both contractors were required to conduct water quality monitoring as part of their technical approach.
The contract included a Phase 1 outcome-based measure of performance (MOP). The MOP is based on a five-year average of Total Phosphorus data from 2019 through 2023. The Phase 1 MOP was a 10% reduction in excess phosphorus for both contractors as measured at the final sampling of the period of performance. We are awaiting results from November and December sampling by DEQ and LACA to make final decisions but the current data indicates both contractors will meet the 10% reduction outcome-based MOP.
LAAC is working on plans for what we want to do in 2025 with the funding we have available. That plan will be presented to the members of the LAAC at the January 2025 meeting. The date for the LAAC meeting is January 23rd at the Louisa County Executive Office building. The public is welcome to attend all LAAC meetings – please attend in January if you are interested in hearing the final results.
The LAAC is seeking funding for implementation of our phosphorus remediation efforts in future years. This project can provide a tremendous benefit to the local community by improving recreation, supporting growth of the local economy, and protecting this valuable resource and downstream uses of water. The lake is an extremely important resource to the region and a focal point for recreation, and it is critical to restore the compromised water quality for the citizens that enjoy the lake.
