By: Shannon Brattebo and Dr. Kateri Salk, Tetra Tech, Inc.
For more than 40 years, Tetra Tech has been a trusted partner for agencies, municipalities, utilities, and associations across the United States, specializing in lake and reservoir management. Our team of limnologists, scientists, and engineers is at the forefront of water quality, criteria development, and lake restoration, earning national recognition for innovative approaches to cyanobacteria control. Our extensive experience spans both large and small waterbodies, planning and implementing in-lake restoration and management strategies.
Tetra Tech provides comprehensive solutions to detect, monitor, and mitigate the impacts of harmful algal blooms (HABs). Our approach integrates advanced water sampling techniques, remote sensing technologies, and data-driven models to predict bloom occurrences and understand the conditions that foster these harmful algal outbreaks.
Tetra Tech’s specialized teams work closely with state agencies, municipalities, and federal clients to develop effective strategies for controlling and reducing the occurrence of HABs.
We also support clients with the implementation of treatment and mitigation measures to protect water resources. Our experience in nutrient management, watershed restoration, and water treatment systems enables us to address the root causes of HABs, such as nutrient pollution from agricultural runoff and wastewater discharges. By combining scientific expertise with innovative technology, Tetra Tech helps safeguard drinking water supplies, improve recreational water quality, and protect aquatic life from the damaging effects of toxic algae.
Tetra Tech offers targeted restoration solutions for HABs. We develop effective restoration plans to reduce HAB recurrence and support the long-term environmental health of each waterbody. Our approach improves water quality and ecosystem resilience by integrating field data and predictive modeling. We use sophisticated field sampling and cutting-edge lab analysis to detect and quantify HAB-related toxins, algae species, and water quality parameters. Tetra Tech’s robust monitoring capabilities include remote sensing, real-time sensors, and in-situ data collection. Our team includes experts in the development of quality assurance project plans (QAPPs) and water quality sampling protocols. We track water quality indicators like nutrient concentrations, chlorophyll, and cyanotoxins to identify early HAB signs. This approach allows for timely, informed action to mitigate impacts, safeguarding water resources and public health. Tetra Tech uses satellite imagery, drones, and aerial sensors to help detect early signs of blooms, monitor their spread, and assess water quality over vast areas. Our remote sensing solutions support quick decision-making, enabling rapid responses to minimize the impacts of HABs.
Tetra Tech’s modeling capabilities are broad and include three- and two-dimensional water quality and advanced hydrodynamic modeling, as well as complex ecological modeling. We simulate conditions that trigger HABs in waterbodies, including nutrient loading, temperature changes, hydrodynamics, and water flow patterns to forecast bloom development, duration, and movement, allowing for timely interventions.
With all the work that we do, Tetra Tech strives to provide our clients with data-driven, clear and effective solutions for water resource management. We recommend solutions that restore water bodies, improve water quality, and enhance ecosystem resilience. Our goal is to provide our clients with concise information and data so they can make informed management decisions and action to mitigate the impacts of HABs, safeguarding both water resources and public health.
Below is a brief summary of projects Tetra Tech is actively working on to help protect and restore our water resources:
Utah Lake Water Quality Modeling, Utah Department of Environmental Quality
Tetra Tech is supporting the development of numeric nutrient criteria for Utah Lake (near Salt Lake City) using a variety of statistical and mechanistic modeling. The modeling efforts include stressor-response analyses to identify relationships among nutrients, HABs, and cyanotoxins, analysis of high-frequency buoy data for real-time HAB responses, and application of the EFDC-WASP (Environmental Fluid Dynamics Code – Water Quality Analysis Simulation Program) lake model to analyze nutrient reduction scenarios. HAB-specific analyses have included statistical modeling of the relationship between cyanobacteria abundance and toxin production, spatial analysis of cell count and toxin impacts in open water vs. beach and marina sites, and species composition of seasonal blooms. The completed nutrient criteria process will include targets for nitrogen and phosphorus that are protective of HAB impacts to recreation on the lake, which could lead to major decreases in the number and length of HAB advisories on Utah Lake. This project also includes stakeholder engagement, development of regulatory language, and updating an interactive online dashboard where users can explore Utah Lake data.
Lake Ketchum Restoration, Snohomish County
BEFORE
Photo provided by Snohomish County
AFTER
Photo provided by Snohomish County
Lake Ketchum faced severe harmful cyanobacteria blooms for over a decade due to high phosphorus levels and legacy phosphorus loading prior to restoration. Since 2010, Tetra Tech has collaborated with Snohomish County and the community to restore the lake’s health. Tetra Tech analyzed nutrient dynamics within and coming into the lake and evaluated multiple nutrient management strategies to reduce phosphorus. An innovative alum treatment program was designed to inactivate sediment phosphorus in the lake and reduce external loading. This management strategy was ultimately chosen by the County and the lake community for implementation. Implementation began in 2014 and has resulted in dramatically decreased algal blooms, eliminating HABs, improving water quality, and restoring recreational use, allowing residents to safely enjoy activities like swimming, fishing, and boating throughout the summer.
Sandusky Bay Water Quality Study, EPA Region 5 and Ohio EPA
Tetra Tech developed an advanced Environmental Fluid Dynamics Code model to create a Watershed Implementation Plan, enhancing understanding of nutrient and sediment transport in Sandusky Bay (OH) and its contribution to HABs. This model was used to support the design and permitting of living shoreline, wetland, and island restoration projects. The model also simulated interactions among nutrients, temperature, light, and aquatic vegetation growth. Tetra Tech also supported design efforts by performing a statistical analysis of factors affecting emergent and submerged vegetation growth in Sandusky Bay.
Nationwide HAB Prediction, EPA
Detecting and managing HABs is critical for both short-term recreational advisories and long-term protection of water uses. Remote sensing technology, such as the EPA’s CyAN Network, has improved HAB monitoring, but monitoring smaller lakes remains challenging due to their size and infrequent sampling. This project’s goal was to forecast HABs by using lake catchment characteristics, morphometry, climate, and nutrient sources. In phase one, a database of relevant data was compiled, and lakes were classified into similar groups. Further modeling by EPA staff will develop a forecasting model based on watershed and lake variables to predict HAB abundance.
Tetra Tech has been making strides in combining satellite data from CyAN with on-the-ground monitoring data for enhanced insights. We are currently developing a HAB vulnerability index for public drinking water systems in Alaska, combining information from the Safe Drinking Water Information System and CyAN for locations that are seldom visited for in-person monitoring. We have also applied CyAN insights to lakes in Arkansas, combined with machine learning analyses that have identified groups of lakes that differ in their bloom patterns as well as nutrient enrichment status and lake characteristics (e.g., lake area, ecoregion, elevation).
