By Harry Looney - May 2024
Harmful algal blooms (HABs) are a significant concern due to their detrimental effects on aquatic ecosystems, human health, and local economies. These blooms, characterized by the rapid growth of cyanobacteria, can have devastating consequences if not properly managed. Lake Anna residents have first-hand knowledge of the issues caused by HABs. We have endured six straight years of recreational, “no swim” advisories issued by the Virginia Department of Health (VDH) for large areas of the lake north of the route 208 bridge based on cyanobacteria cell counts that exceeded established health and safety thresholds.
Research indicates that cyanobacteria thrive on excess nutrient loads (phosphorus and nitrogen) found in the water and sediments of lakes. Historical data collected by LACA and the Virginia Department of Environmental Quality (DEQ) indicate that large areas of the upper Lake Anna reservoir ecosystem are “out of balance” due to nutrient pollution. These data indicate that areas of the upper reservoir have been eutrophic, meaning there is too much phosphorus, nitrogen, and chlorophyll, since at least 2005 and these areas remain above eutrophic thresholds year-round.
Based on insights gained from LACA’s cyanobacteria monitoring efforts and our demonstration of established, well-researched cyanobacteria mitigation technologies in 2022 and 2023, LACA’s leadership worked to obtain state funding in Virginia’s fiscal year (FY) 2024 budget to initiate actions to mitigate and remediate cyanobacteria levels in the upper Lake Anna reservoir. Many of you wrote letters of support for the legislation and we thank you for doing that. The result of LACA’s action, your letters of support, and the fact that HAB control is a legislative priority of both Louisa and Spotsylvania counties was a $1 million appropriation from the Virginia General Assembly for cyanobacteria mitigation and remediation. 
The state funding is being executed by the Lake Anna Advisory Committee (LAAC) with Louisa County providing financial oversight and contracting support. A Request for Proposals was released in December 2023 that resulted in the submission of two competitive offers. After careful evaluation of the offers, LAAC and Louisa County awarded contracts in March to Clean Streams, Rivers, and Lakes (CSRL)located in Fairfax, Virginia and EutroPHIX – A Division of SePRO Corporation located in Carmel, Indiana. The contract includes a base year that is funded by the $1 million state appropriation and four, unfunded, 1-year options that can be adjusted and awarded as follow-on funding is received from state and federal appropriations.
The name of the LAAC program is the Lake Anna Cyanobacteria Mitigation and Remediation Program. The goal of the program is to achieve a safe and naturally balanced phytoplankton biomass in the ecosystem of the upper Lake Anna reservoir. The program has two objectives that must be met to achieve the program goal. The first objective focuses on the root cause of the problem, nutrient pollution with a target to reduce and sustain phosphorus levels at all monitoring stations in the upper reservoir below eutrophic levels. The second objective is to achieve ecosystem balance with respect to the phytoplankton biomass across the entire upper Lake Anna reservoir.
The technical approach being implemented by both contractors focuses on the use of approved, safe, and environmentally friendly chemicals that “mineralize” the phosphorus and make it unusable by the cyanobacteria biomass. The CSRL technical approach also includes the introduction of beneficial bacteria that consume nutrients flowing into the lake from the watershed. Dominion Energy conducted an in-depth technical review of the EutroSORB and CSRL products and has approved their use in the upper Lake Anna reservoir.
The $1 million state appropriation being used to fund the first year of the contract is sufficient to start phosphorus remediation activities in two of the three upper Lake Anna tributaries. EutroPHIX will be working in the upper North Anna River and CSRL will focus on Terry’s Run. Phosphorus remediation actions will begin in Pamunkey Creek and continue in the upper North Anna River and Terry’s Run in follow-on contract years. Pamunkey Creek was not included in year 1 of the contract due to the funding being insufficient to begin remediation activities in all three tributaries. The decision was also impacted by the ongoing work by DEQ to collect data as part of the state funded study. Neither DEQ nor LAAC wanted to negatively impact the data being collected to identify sources of nutrient pollution in Pamunkey Creek. For those of you living along Pamunkey Creek, the plan is to begin work in your area in 2025.
The EutroPHIX technical approach involves the inactivation of sediment phosphorus with EutroSORB® G in areas of the upper North Anna River, coupled with an automated injection treatment of EutroSORB® WC into the North Anna River approximately 1.25 miles north of the lake. EutroSORB contains the naturally occurring element lanthanum that has a very strong affinity to bind and “mineralize” phosphorus. Lanthanum-based products have been used in ponds and lakes of similar size to the upper Lake Anna reservoir for more than 20 years so there is plenty of past evidence that these formulations work well to reduce phosphorus levels. The lower phosphorus levels have the beneficial side-effect of reducing the cyanobacteria biomass due to the reduction of available food/energy sources.
The CSRL technical approach utilizes a calcium silicate formulation called Wollastonite to inactivate phosphorus in Terry’s Run and an innovative approach using bioreactors containing beneficial bacteria near the inflows of the creeks and streams that feed Terry’s Run. The beneficial bacteria are voracious consumers of phosphorus and nitrogen. These bioreactors are used to address the phosphorus and nitrogen flowing into the lake from the watershed.
The efforts completed in year 1 of the contract set the stage for continued treatments across the entire upper Lake Anna reservoir. The approach is designed to be spread out over a 4-5 year period of time to ensure the ecosystem is not “shocked” by a major treatment that lowers phosphorus too quickly for the phytoplankton, zooplankton, and fish species to adjust to.
Embarking on a program, especially a complex or large-scale one as is the case for a nutrient remediation effort, involves several stages and a considerable amount of time and effort. It is great to see a full-scale effort being implemented to manage the cyanobacteria issues we experience at Lake Anna. LACA will continue to implement watershed best management practices that complement what is being accomplished in the Lake Anna Cyanobacteria Mitigation and Remediation Program and we will work collaboratively with LAAC and the counties to obtain funding to continue and complete the effort that is just beginning in 2024.
Please contact the LACA Program Manager if you want to get involved in our volunteer efforts or if you want to get more information on cyanobacteria / HAB issues at Lake Anna.
harry.looney@lakeannavirginia.org
