he Government Accountability Office (GAO) report GAO-22-104449, titled “Water Quality: Agencies Should Take More Actions to Manage Risks from Harmful Algal Blooms and Hypoxia,” provides a detailed analysis of the current state of harmful algal bloom (HAB) and hypoxia management in the United States.
The report highlights the need for a more comprehensive, proactive, and systems based approach to address these critical water quality issues.
The GAO report emphasizes the significance of hypoxia as a major contributor to the degradation of aquatic ecosystems. Hypoxia, (defined as dissolved oxygen levels below 2.5mg/l) in water bodies, creates “dead zones” that are inhospitable to most aquatic life.
The report identifies the decomposition of organic sediments as a primary driver of hypoxia in many water bodies. As excessive algal blooms die off and sink to the bottom, they form a layer of organic matter that consumes oxygen during decomposition.
This process depletes dissolved oxygen levels in the water column, particularly in the deeper, stratified layers, leading to hypoxic conditions.
The GAO report explains that self-reinforcing feedback loops perpetuate the cycle of eutrophication, hypoxia and algal blooms.
Excessive nutrient inputs, often from human activities such as agriculture and wastewater discharge, fuel the growth of algal blooms. As these blooms die and sink, they contribute to the accumulation of organic sediments, which, as they decompose consume oxygen, causing hypoxia and further algal growth as nutrients are released back into the water column.
Hypoxic conditions have severe consequences for the health and functionality of aquatic food webs.
The report emphasizes that low oxygen levels can lead to the loss of essential habitat for fish, invertebrates, and other organisms that play crucial roles in maintaining ecosystem balance. As these populations decline, their capacity to consume algae and clear excess nutrients from the water is diminished, further exacerbating the problem.
Within the report, the GAO warns against using algaecides as a primary means of controlling HABs.
While algaecides may provide temporary relief by killing off visible algal blooms, they can cause toxin release from dead cyanobacteria cells and they ultimately contribute to the underlying problem.
The sudden death and decomposition of algal biomass caused by algaecides can intensify oxygen depletion and nutrient release from sediments, fueling future blooms and hypoxia.
This same principle applies to ultrasonic algaecides and chemical herbicides.
The report emphasizes that the cumulative effects of eutrophication; algal blooms, hypoxia, and degraded food webs create positive feedback loops that create conditions that are increasingly favorable for the development of HABs.
As ecosystems become more imbalanced and less resilient, the likelihood of toxic cyanobacterial blooms increases, posing significant risks to human health, wildlife, and local economies.
The GAO report stresses the importance of shifting from reactive, symptom-focused management strategies to proactive, prevention-oriented approaches.
Relying solely on monitoring for HABs and implementing control measures like warning signs and algaecide treatments after they have occurred fails to address the root causes of the problem. The report calls for the development and adoption of more robust, intelligent protocols and practices that prioritize the prevention of eutrophication and hypoxia.
To support a proactive management approach, the GAO report calls for enhanced monitoring and forecasting capabilities. Effective monitoring should go beyond simply detecting the presence of HABs.
A comprehensive methodology for the assessment of the status and rate of progression of key driving factors such as hypoxia, sediment accumulation, phytoplankton composition and negative impact on the food web and aquatic biodiversity is required.
The report also emphasizes the importance of using such methodologies to develop predictive risk-based models and early warning systems that can forecast the likelihood of HAB and hypoxia events, enabling resource managers to take preventive actions.
The report recognizes the need for a more strategic and data-driven approach to assessing the eutrophic status of water bodies.Given the vast number and diversity of water bodies affected by HABs and hypoxia, it is essential to develop objective criteria and methodologies for comparing and ranking them based on common factors related to the status and rate of progression of key driving factors such as hypoxia, sediment accumulation, phytoplankton composition and negative impact on the food web as well as factors such as ecological significance, economic value, and public health risks.
These objective comparators should help prioritize water bodies objectively across parameters such as size, depth, geographic location. This objective scoring and prioritization will help ensure that limited resources are allocated effectively and that management actions are targeted to the most critical areas.
The GAO report underscores the need for innovative solutions that can effectively reverse eutrophication and hypoxia, thereby preventing the occurrence of HABs.
While the report does not provide specific recommendations on the types of solutions needed, it emphasizes the importance of exploring new technologies, management strategies, and policy approaches that can address the root causes of these problems.
This may include advanced wastewater treatment technologies, nature-based solutions for nutrient reduction, and more stringent regulations on nutrient inputs from agricultural and urban sources.
The interagency working group, led by EPA and NOAA, has not fully implemented a national HAB and hypoxia program as directed by the Harmful Algal Bloom and Hypoxia Research and Control Act.
Recommendation: The GAO recommends that the agencies define what such a program would entail and identify the resources needed to implement it, yet nothing appears to have been done.
Federal agencies have taken limited actions to monitor and forecast HAB and hypoxia events in freshwater bodies, despite the significant risks they pose.
Recommendation: The GAO recommends that EPA, working with other agencies, develop interagency frameworks to expand monitoring and forecasting of freshwater HABs and hypoxia, including prioritizing water bodies and identifying resource needs.
Using algaecides and other symptomatic treatments is counterproductive and can actually accelerate eutrophication and the onset of HABs.
Recommendation: The GAO identifies the need for a more comprehensive, ecosystem-based approach to reverse eutrophication to enable proactive, preventive risk management based approaches.
The report highlights the lack of a national goal focused on proactively preventing HABs and hypoxia, not just reactively responding to them. This requires a shift in focus from addressing the root causes of eutrophication rather than merely treating the symptoms.
Recommendation: The GAO recommends that such a goal be established and innovative technology and management approaches be adopted.
The GAO concludes that prevention is always more effective as policy and more affordable.
Recommendation: The GAO recommends that the interagency working group, led by EPA and NOAA, coordinate the development of more comprehensive information on the costs and benefits of mitigation, control, and prevention actions for HABs and hypoxia to help make more informed decision making and policy.
