Algae & Harmful Algal Blooms – Aquarius-Systems

Misconceptions About Lake Health and the Risks of Chemical Treatments

Wed, 01 Oct 2025 15:32:25 +0000

Lakes across the country are struggling with harmful algal blooms, low oxygen, and declining fish populations. While these problems are often obvious at the surface, many management practices are based on misconceptions that don’t address the real causes. Instead of solving the issue, they often make lakes even sicker.

Chemical Treatments: A Short-Term Fix That Makes Things Worse
Many lake managers turn to algaecides and herbicides to control harmful algae. On the surface, these treatments may look effective, but the reality is very different.

When algae are killed by chemicals, the cells release toxins directly into the water. The dead material then sinks, decomposes, and consumes oxygen—creating hypoxic conditions that stress or kill fish. Low oxygen also triggers internal nutrient release from sediments, fueling the very blooms that the chemicals were meant to stop.

Instead of restoring balance, chemical treatments can lock lakes into a cycle of recurring blooms and declining water quality.

Looking at the Surface Isn’t Enough
It’s common to judge a lake’s health by what can be seen at the surface—clear water, healthy oxygen levels near the top, or visible fish. But many lakes stratify, with deeper waters cut off from oxygen. While the surface looks fine, the bottom layers can be oxygen-depleted and nutrient-rich.

Fish crowded near the surface aren’t thriving—they’re escaping conditions that are deadly below.

Runoff Isn’t the Only Problem
Nutrient runoff from land is an important driver of algae, but it’s not the only one. Sediments at the bottom of lakes often act as storage banks for phosphorus and nitrogen. When oxygen levels drop, these nutrients are released back into the water, feeding new blooms year after year.

Focusing only on reducing runoff misses the internal nutrient cycle already at work inside the lake.

The Limits of Simple Metrics
Common tools like the Trophic State Index (TSI) are often used to measure lake health. But they mostly track surface-level data like clarity and nutrient concentrations. These numbers don’t reveal what’s happening in deeper waters, or how sediments and oxygen loss are driving long-term decline.

A Call for Smarter Lake Management
The misconceptions around lake health—and the overreliance on chemicals—are keeping many lakes stuck in poor condition. Chemical treatments may offer short-term relief, but they create long-term problems.

To break the cycle, management strategies need to focus on oxygen restoration, sediment nutrient control, and ecosystem balance. Prevention and smarter monitoring are also key to creating lakes that are resilient, healthy, and able to support aquatic life for generations.

Glyphosate Ban Necessary Call for Lake Okeechobee

Tue, 05 Dec 2023 20:47:03 +0000

While officials admit that glyphosate is only a small part of the problem with algae blooms on Lake Okeechobee in Florida, they do believe that their decision to temporarily suspend the use of aquatic plant killers was a “necessary call.”

Glyphosate is widely used in Lake Okeechobee to kill invasive species and leaves deposits of phosphorus in the waters. The plants that have been killed by the herbicide treatment sink to the bottom where it turns into sediment and release additional phosphorus. This phosphorus feeds the blue-green algae blooms that have choked the waters in recent years.

Research suggests that the phosphorus deposited as a result of Roundup sprayed by the Florida Fish and Wildlife Conservation Commission is 2,943 pounds plus the phosphorus contributed by the decaying aquatic vegetation; a drop in the bucket compared with the 2.3 million pounds finding its way into the lake. However, without the ability to find a “big” solution to the phosphorus problem, small remedies such as the herbicide suspension, are the only available remedies.

Algae Treatment Leads to Massive Fish Kill in Lake Isabella

Fri, 01 Dec 2023 18:16:49 +0000

Lake Isabella has experienced a significant “fish kill” due to low oxygen levels following treatment of an extremely high blue-green algae presence.

When the heavy bloom was noted a recommendation was made to close the lake to swimming and boaters and a company was hired to treat the lake with a chemical called SeClear. The following day, hundreds of dead fish were observed lying dead on the bottom and floating on the surface.

Workers went around netting the dead fish. The numbers showed 1,105 small largemouth bass killed, 181,888 bluegill fingerlings, 7,635 larger bluegill, 26 white crappie, 3 grass carp and 10 channel catfish killed. All of the fish were buried in the Village gravel pit.

Chemical Turns Polluted Green Lakes Clear

Fri, 18 Aug 2023 17:42:11 +0000

A history of pollution is sparking a colorfully devastating scourge in lakes across the country: algae blooms. These events can turn pristine waterways to pea soup, choking out wildlife and toxifying water. Increasingly, scientists are fighting back with chemical warfare, injecting aluminum sulfate into lakes to neutralize the pollutants that fuel the blooms.

Aluminum sulfate, or alum, has an affinity for phosphorus. In water, alum assumes a cotton-candy-like form, “a nice fluffy floc.” This floc (short for flocculation) grabs phosphorus and other particles as it settles to the bottom of the lake, flipping the water from cloudy to clear.
Like any method of ecosystem restoration, dumping thousands of gallons of alum into a lake is not risk-free. If pH plummets during an alum treatment, the usually benign chemical—often used to purify drinking water—can turn toxic for wildlife.

Toxic Blue-Green Algae Kills More Than a Hundred Elk

Wed, 07 Dec 2022 17:01:04 +0000

A hunter stumbled upon a bizarre sight on a 75,000-acre ranch north of Las Vegas, N.M., on Aug. 27: the remains of more than 100 dead elk. Livestock deaths are not unusual, but so many animals dying off, and doing so in what seems to be under 24 hours, was puzzling to scientists

Officials with the New Mexico Department of Game and Fish investigated the mysterious elk deaths and ruled out several possible causes for the elk deaths, including poachers, anthrax, lightning strikes, epizootic hemorrhagic disease (an often-fatal virus known to affect deer and other ruminants), botulism, poisonous plants, malicious poisoning and even some sort of industrial or agricultural accident.

Through science and further testing of elk tissue samples and water samples, it was determined that pond scum was the culprit. Or, more specifically, a neurotoxin produced by one type of blue-green algae that can develop in warm, standing water.

Restoration Of Wetlands Can Be The Best Purification Strategy For Nitrate-Laden Water

Fri, 04 Feb 2022 21:31:40 +0000

A new study maps the potential of wetlands – an ecosystem flooded with water and supporting a vegetation of aquatic plants – to improve water quality. Through the study, the researchers claim that regrowing wetlands can act as a key strategy for improving water that is laden with contaminants like nitrate.

Nitrates reach groundwater, rivers, and coastal areas through runoff from fertilizer and manure application in agricultural regions. High nitrate levels can ultimately threaten the supply of drinking water and also lead to “problems with algal blooms and degradation of aquatic ecosystems.

The scientists now imagine wetlands as a solution. This is because when nitrate-laden water enters the boundaries of wetlands, a chemical reaction takes place that has a purifying effect on the water. The reaction releases harmless nitrogen gas into the atmosphere and thus results in cleaner water to flow downstream.

Invasion of the Algae Blooms!

Fri, 04 Feb 2022 21:08:16 +0000

As many Americans plan trips to lakes and river this Labor Day Weekend, experts are sending out a warning to watch out for toxic algae blooms.

Researchers identified 318 bodies away in the US that have been infected by the microscopic organism called cyanobacteria.

Approximately 86 percent of the outbreaks were in recreational areas, but other reports note a number of dogs and cows were killed.

10,000 Dead Fish at Lake Mission Viejo after Toxic Algae Outbreak

Wed, 05 Jan 2022 21:34:54 +0000

An outbreak of toxic algae has killed almost all fish at Lake Mission Viejo, a world-class bass fishery in California.

An estimated 10,000-plus bass, catfish, sunfish and blue gill have died in the past few months at the man-made recreational lake, said Kevin Frabotta, general manager of the Lake Mission Viejo Association, the homeowners association that owns the lake.

Lake staff discovered dead fish in early November and lab tests showed they were dying as a result of a toxin produced by prymnesium parvum, also known as the golden algae, the HOA website stated. HOA employees have been treating the lake with algae suppressor and testing water samples twice a week since then, Frabotta said.

Staff stock Lake Mission Viejo with trout every winter, but the association has been delaying restocking until the lake condition recovers. They’ve released about 15 sample trout to test the water, but all died within two hours, Frabotta said.

Seaweed Farms a Possible Solution to Algae Blooms

Wed, 05 Jan 2022 19:49:24 +0000

Marine ecosystems suffer from nutrient pollution, as most of our waste tends to get dumped in the sea. This kind of pollution can become very deadly, as high levels of nutrients foster algal blooms which destroy water quality and deplete its oxygen — in short, they kill everything else around them.

New research at the University of California Santa Barbara suggests that aquaculture could help prevent such issues in the future. A study proposes seaweed farms as a possible solution, especially for nitrogen and phosphorus. Such farms would be able to scrub large amounts of nutrients even after they’ve made their way into the ocean at relatively low costs.

Wyoming Game and Fish Exploring Ways to Address Algae

Wed, 05 Jan 2022 19:28:46 +0000

Whether you visited Renner Reservoir for the first or 10th time this summer, you probably noticed a branchy, aquatic algae called chara covering the bottom of the reservoir.

Compared to other aquatic plants, which are referred to as macrophytes, chara forms denser mats offering less habitat for fish and a less palatable meal for invertebrates. At high enough densities, chara can have negative ecological impacts on aquatic environments and be a nuisance to boaters and anglers.

Game and Fish explored an option to address this problem by treating two small portions of the reservoir with an algaecide. The goal of the treatment was to learn what tools might effectively control the overabundant macroalgae.