A science-based solution for tackling lake health

Experts urge moving away from short-term ‘fixes’ that only worsen a lake’s condition over time, and instead advocate for a holistic, science-based strategy that tackles the underlying causes of lake health to revitalise the entire ecosystem.

Lakes are more than just bodies of water; they are vital ecosystems that support diverse life forms, provide recreational enjoyment and sustain local economies. Yet, across the US, these precious resources are under threat.

The water quality in lakes is declining at an alarming rate, leading to severe repercussions. Observable indicators of this deterioration include the emergence of symptoms such as invasive weeds, algae blooms, the emission of unpleasant odours and ‘fish kills’.

When a crisis occurs, specialists are called in to evaluate and oversee the situation. Diagnostic tests are performed to confirm the presence of a harmful algae bloom (HAB) — a fact that usually is already evident. Frequently, the application of chemicals like biocides is advised.

While the notion of eradicating algae to improve the lake’s appearance before an upcoming holiday is enticing, this can lead to a detrimental cycle that accelerates the deterioration of the lake’s ecosystem.

The elimination of algae results in the release of toxins, leading to the destruction of more beneficial organisms and favouring the proliferation and dominance of the harmful organisms in the lake. Over time, the continued application of algaecides causes lake algae blooms to worsen. In other words, the symptoms are treated temporarily, but the patient never gets better.

The US Government Accountability Office (GAO) has confirmed the severity of this issue. The findings are clear: we are losing the battle to protect our lakes, and unless we change our approach, the situation will continue to deteriorate. As a result, many experts are urging a different approach and a more permanent solution.

“The goal should be to reverse the damage and restore these vital ecosystems, but to do so, we must revise and sometimes abandon practices of the past that have been widely recognised to be ineffective and embrace a new way of managing our lakes — one that is proactive, science-based and focused on addressing the root causes of degradation,” said Dr Wayne Carmichael, a prominent expert in aquatic toxicology, known for his work on toxic cyanobacteria.

Carmichael has over 500 peer-reviewed papers, publications and presentations, and has consulted on cyanobacteria issues in over 25 countries. He advises federal, state and local agencies, participates in national and international committees, and has contributed to reports for the World Health Organization.

Fortunately, there are effective, comprehensive solutions that can help in the fight to save our lakes. The solution is a multifaceted approach that addresses the root causes of water quality degradation. Ultimately, this approach can improve water quality, enhance recreational opportunities and preserve aquatic ecosystems for future generations.

The root causes of lake deterioration

The decline in lake health is driven by several interconnected factors, described in general as eutrophication. Eutrophication is the technical term for the process that occurs when water bodies become overly enriched with nutrients, resulting in sediment nutrient accumulation.

These nutrients are recycled back into the water, fuelling further algae growth and creating a feedback loop that perpetuates the cycle of degradation. A tipping point is eventually reached when sediment nutrient recycling is sufficient to sustain eutrophic conditions and facilitate a switch to cyanobacteria dominance. In short, HABs become more prevalent, persistent and intense.

According to Carmichael, the cause of eutrophication is well established. While some levels of nutrients are natural, human activities such as agriculture and urban runoff have accelerated eutrophication to dangerous levels, overwhelming nature’s capacity to clear out these nutrients and maintain balance. Whether caused by climate change or not, the water temperature of lakes is increasing, further fuelling eutrophication.

Unfortunately, many lake management strategies often prove inadequate because they target the symptoms rather than the root cause factors that drive eutrophication in lakes.

In search of more permanent solutions

According to Carmichael, effective restoration of lake and water reservoir health begins with monitoring key metrics that go beyond confirming the poor condition of the lake. These metrics should assess the entire ecosystem and provide indicators that can be used to evaluate sustained improvement.

“[As an agency and industry] we have done a good job of monitoring, but now we need to get more serious about remediation and prevention,” Carmichael said.

This does not include simply applying air, flocculating/binding agents or algaecides as a quick fix. Treating the symptoms in this way often causes a rebound effect, where the underlying issues become more severe over time.

“Chemical and physical methods either dampen the effects of a bloom or shorten the bloom, but do not prevent the bloom,” said Carmichael, who notes that the net effect is often only to temporarily improve lake conditions for a few weeks or months.

The truth is that in most cases biocides, whether herbicides or algaecides, only make the problem worse. Algaecides are more effective against beneficial algae than cyanobacteria, and cyanobacteria are better able to recover after each application.

By killing algae and cyanobacteria cells, toxins are also released, and the dead cells sink to the bottom and compound nutrient recycling when they decompose. As algae die and decompose, oxygen is consumed in the water, leading to hypoxic conditions — ‘dead zones’ where aquatic life cannot survive. Hypoxia is a major driver of fish kills and the loss of biodiversity in lakes.

Addressing the root cause, therefore, means properly managing sediment accumulation.

“In most cases, the nutrients become part of the sediment, which becomes part of the permanent morphology of the lake,” Carmichael said.

An important first step is to identify methods that recycle properly in a natural way those nutrient-rich sediments without “just physically removing and dumping them somewhere [through dredging techniques] but allowing them to be used in the lake ecosystem because nutrients are needed for organisms to grow”, Carmichael said.

“Most of the nutrients are organic and can be recycled back through the food web to benefit the natural cycle of the lake — not the HAB cycle of the lake,” he added.

Addressing hypoxia by ensuring adequate oxygen levels in the water is also crucial for maintaining a healthy lake ecosystem. Although there are many different solutions that can be used to help revive a lake ecosystem, one promising category involves utilising Rapid Acting Dissolved Oxygen Restoration (RADOR) technology. Numerous studies have demonstrated that high, stable oxygen levels reduce nutrients and minerals in the water column and can keep phosphorus locked into the organic sediments.

“RADOR helps ensure that the necessary increase in oxygen levels is properly maintained throughout the entire water column within a lake,” said Dave Shackleton, President of Clean-Flo International — a US-based leader in biological water management solutions for managing water quality in biological environments such as wastewater treatment, rivers, lakes and reservoirs.

“By increasing dissolved oxygen levels throughout the water column, the RADOR system initiates a sequence of events that bio-dredge mucky sediment, control aquatic weeds, improve water quality, [and] reduce organic muck, nutrients, odour, harmful gases and coliform bacteria. This helps to restore the nutrient clearing capacity of the food web by improving fish growth and health,” Shackleton explained.

Clean-Flo designs its RADOR systems using compressors of various sizes based on the lake and application, along with self-sinking airline and diffusers that maintain full oxygenation from the bottom to the surface of the water.

“Another important step in restoring balance to a lake is bioaugmentation, which involves the use of enzymes to break down organic muck, like a compost pile. Boosted by natural enzymes, aerobic bacteria and microorganisms consume the organic muck and nutrients, while aquatic insects feed on the bacteria, increasing the natural food source for fish,” Shackleton said.

Critical micronutrients can also be introduced to stimulate the growth of organisms that form the foundation of a productive food web. This enables balance to be restored at the level of phytoplankton, so that beneficial algae can outcompete the toxic cyanobacteria, preventing HABs and providing better nutrition for the food web. The food web becomes more productive so that nutrient clearance is restored and sediment nutrient stockpiles are depleted as they are bio-dredged away.

Consistent use of these products over time reduces nutrient availability and helps maintain clean, healthy water. As water quality improves, swimming conditions get safer. The reduction of organic sediments helps control aquatic weeds by minimising the nutrient-rich rooting bed that mucky sediment provides for their growth.

According to Shackleton, these are only a few of the available solutions, and customised programs based on the specific conditions of each lake are typically required to ensure restoration and long-term lake health.

“To preserve our nation’s lakes, the industry must adopt a new approach to lake management — one that supports nature and addresses the root causes of degradation,” Shackleton said. “Working with nature, rather than against it, is key to restoring lake health.”

Image credit: iStock.com/Willard