Glyphosate in Our Lakes: Hidden Risks and Better Alternatives

From Quick Fix to Environmental Fallout

Spraying glyphosate on water may clear the surface in the short term, but it sets off a cascade of environmental problems. When herbicides like glyphosate kill aquatic plants, the dead vegetation doesn’t magically vanish – it sinks to the bottom and begins to decompose. This decaying mass of plant matter sucks oxygen out of the water as it breaks down, creating low-oxygen conditions that can suffocate fish and other aquatic life . Rapid die-offs of weeds have been known to trigger fish kills in ponds because of this sudden drop in dissolved oxygen.

Beyond the immediate oxygen crash, all that rotting biomass turns into muck and releases nutrients that had been locked up in the plants. Phosphorus, in particular, is leached out from the decaying weeds. In Lake Okeechobee’s case, officials acknowledged that glyphosate treatments leave behind phosphorus in the water . This extra phosphorus then feeds algal blooms – outbreaks of algae that turn the water green and can produce toxins. It’s a cruel irony: the very act of spraying weeds can boomerang back as a blue-green algae bloom choking a lake . Lake Okeechobee has suffered massive toxic algae blooms in recent years, and while runoff from farms is the main source of nutrients, weed-killing chemicals add a “drop in the bucket” of phosphorus that further fuels the problem .

Another hidden issue is the buildup of sediment and muck. Every time weeds are killed but left in place, they contribute to the layer of organic sludge on the lake or canal bottom. Year after year of herbicide spraying becomes a cycle: weeds die, sink, and rot into fertilizer for the next generation of weeds . Over time, this can make the waterbody shallower and murkier, and it can worsen invasive weed problems by enriching the water with nutrients. In other words, chemical spraying often treats the symptom (visible weeds) while worsening the root cause of the issue (excess nutrients and organic matter) .

And what about the glyphosate chemical itself? Manufacturers often claim that glyphosate breaks down quickly in the environment, but studies show it can persist, especially in sediments. Glyphosate is highly water-soluble, yet it binds tightly to soil and underwater sediment particles . Once attached to lake bottom mud, glyphosate doesn’t readily wash away – it lingers until soil microbes break it down. The herbicide’s main degradation product, AMPA, is even more stubborn: in lake sediments, AMPA can have a half-life of up to 2–3 years . This means residues of past herbicide applications can accumulate in the sediment over time. Indeed, a recent U.S. Geological Survey study found glyphosate and its byproducts are now detected in the majority of streams and rivers tested . Although the concentrations were below acute toxicity benchmarks, the ubiquity of these chemicals in water is a red flag – a reminder that what we spray doesn’t just disappear.

Aquatic ecosystems are complex, and glyphosate spraying can disrupt them in subtle ways beyond the obvious fish kills or algae blooms. Aquatic herbicides are usually non-selective, meaning they can kill beneficial native plants along with the targeted invasive ones . Removing too much vegetation (even weeds) in one swoop can eliminate habitat for fish, birds, and amphibians. There’s evidence that some formulations of glyphosate (especially those with certain surfactants) are directly toxic to amphibians and other small aquatic organisms . Even when using “aquatic approved” formulas, there’s concern about long-term impacts on the food web and water quality that we are only beginning to understand . In short, dumping glyphosate into water may be easy, but its environmental price is paid over months and years by the lake and its living community.

Known Health Risks: Glyphosate’s Dark Side

It’s not just fish and frogs at risk – glyphosate has been linked to serious human health concerns. You may recognize Roundup™ as the weed killer at the center of thousands of cancer lawsuits. Glyphosate is Roundup’s active ingredient, and in 2015 the World Health Organization’s cancer research arm declared glyphosate “probably carcinogenic to humans.” Fast forward to today: over 125,000 Americans have filed claims saying Roundup exposure gave them cancer (often non-Hodgkin’s lymphoma) . Juries have agreed in several high-profile cases, and the litigation pressure pushed Bayer (which acquired Monsanto, Roundup’s maker) to announce a $10 billion settlement in 2020 to resolve current and future glyphosate cancer lawsuits . It’s one of the largest product-liability settlements in history – over ten billion dollars set aside because so many people allege this chemical made them gravely ill.

Despite this, glyphosate continues to be sold and used. Regulators like the U.S. EPA maintain that glyphosate is safe if used as directed, and have not officially recognized it as a carcinogen . This regulatory stance is one reason glyphosate use carries on (we’ll explore more reasons shortly). However, many scientists and public health experts are uneasy. The sheer volume of lawsuits and independent studies linking glyphosate to cancer, endocrine disruption, and other health issues have created a growing consensus that this herbicide is not as benign as once thought. Several countries and local governments have moved to ban or restrict glyphosate. In the U.S., some cities have stopped using it in parks to protect public health.

So, what does spraying glyphosate in water mean for people? For one, if you live around a lake or canal that’s routinely treated, you, your kids, and your pets could be swimming or fishing in water with chemical residues. While aquatic formulations of glyphosate are designed to be water-safe, no herbicide is completely without risk. People can be exposed through skin contact or by incidentally ingesting water while swimming. There’s also the concern of glyphosate making its way into drinking water sources. Glyphosate binds to sediments and usually doesn’t travel far into groundwater , but in some cases runoff could carry it to wells or reservoirs. Even at low levels, the presence of a probable carcinogen in our water is unsettling.

Moreover, when lakes develop the toxic algae blooms we mentioned (often a consequence of heavy nutrient loading from dead weeds and other sources), those blooms pose their own health hazards – from rashes and respiratory issues to liver toxins in drinking water. While glyphosate isn’t directly causing the algae, the chain reaction it sets off can deteriorate water quality to the point of making lakes unsafe for recreation or consumption. Essentially, spraying glyphosate in water trades one problem (weeds) for another (chemical and biological pollution). For the sake of our health and our environment, it’s worth asking: Why are we still doing this?

Why Is Glyphosate Still Being Used in Our Waterways?

If glyphosate is so risky, why do many lake managers, homeowner associations, and public agencies keep using it? There are several practical and historical reasons driving the continued use of glyphosate-based herbicides in water:

• Cost and Convenience: For many, glyphosate is simply the cheapest and easiest tool to control aquatic weeds. Hiring work crews or investing in specialized weed-harvesting equipment can cost significantly more. One township in Michigan noted that mechanical harvesting can cost up to four times more than chemical treatment for the same area. Spraying can be done by a small team (or even one person in a boat) relatively quickly, whereas mechanical removal is labor-intensive. Budget-strapped local governments often opt for the least expensive short-term solution, which is usually a jug of herbicide.
• Effectiveness (Short-Term): Glyphosate is a broad-spectrum, powerful herbicide. It reliably kills most plant species down to their roots. From a manager’s perspective, a single application can knock back an infestation of water hyacinth or cattails within days or weeks. The visual impact of “no more weeds” is immediate gratification. In contrast, other methods might not clear 100% of the plants or might take longer to show results. This quick knockdown gives glyphosate a reputation as a silver bullet for weed problems – even if that silver bullet comes with collateral damage.
• Regulatory Green Light: As mentioned, the EPA and many state agencies still approve glyphosate for aquatic use, deeming it safe when used according to label instructions. Most aquatic glyphosate products are certified for use in water (with some precautions, like avoiding application near drinking water intakes). For example, an aquatic glyphosate formula typically has no swimming or fishing restrictions after use . This official approval gives lake managers confidence that they’re following “best practices” and not breaking any rules. Essentially, if it’s legal and on the approved list, it feels justified.
• Inertia and Tradition: Chemical control of aquatic weeds has been the norm since at least the mid-20th century. Generations of water management professionals have been trained to use herbicides as a primary tool. There’s an entire industry of lake management companies that default to chemical treatments. Changing established routines is hard – it requires new training, new equipment, and sometimes a new mindset. In many areas, “weed spraying” is simply what has always been done, and it continues unless someone pushes for an alternative plan.
• Lack of Awareness: Many decision-makers and community members may not fully grasp the hidden costs of glyphosate use. They see the weeds disappear, but aren’t measuring the oxygen levels at 2 AM when fish might be dying, or testing the sediment for residual chemicals. The negative impacts can be delayed or diffuse, making them easier to overlook. At the same time, the benefits of alternatives (like physical removal) might not be widely known or understood. This knowledge gap can lead to well-meaning people sticking with herbicides because they aren’t aware a better way is feasible.

In short, glyphosate remains in use due to a mix of economics, convenience, and habit. But just because it’s been the status quo doesn’t mean it’s the smartest or most sustainable choice going forward. We now know more about what relentless chemical use does to our water. Thankfully, we also know there are safer, more effective alternatives that can replace or drastically reduce our dependence on aquatic herbicides.

A Better Way to Manage Weeds: Mechanical Removal and Beyond

Imagine tackling an overgrown pond without poisoning the water. It’s entirely possible – and increasingly practical – to manage aquatic weeds through mechanical and ecological methods. The principle behind these alternatives is simple: remove the excess plants from the water, rather than spraying them in place. By physically removing weeds, we solve the weed problem and avoid the pitfalls of decay and chemical pollution. Here are some key alternatives, with a focus on mechanical removal:

Mechanical Weed Harvesting: This method uses specialized machines (think of them as aquatic lawn mowers or combine harvesters) to cut and collect weeds. Harvesters are barge-like boats equipped with cutting blades and conveyor belts. An operator drives the harvester through the infested area, cutting the plants and loading them onboard. The collected weeds are then offloaded onshore and hauled away. Unlike herbicides, mechanical harvesting introduces nothing foreign into the water – it’s purely a removal process. The benefits of this approach are profound:

• No Dead Zones: Because the weeds are physically removed, they don’t sit underwater and decompose. That means no sudden oxygen crash and far less risk of fish kills compared to herbicide spraying .
• Nutrient Export: Every load of weeds hauled out of a lake is a load of nutrients (nitrogen, phosphorus, etc.) taken out with them . This is crucial. Harvesting literally removes the fuel for algae blooms and future weed growth from the system. By contrast, herbicide kills leave all those nutrients in the water to cycle again. Mechanical removal has been shown to greatly reduce the biomass that would have rotted and released nutrients, thus improving water quality .
• No Chemical Residue: With no herbicides used, there’s zero risk of chemical exposure to humans or wildlife, and no lingering residues or byproducts. The water can be used immediately for swimming, fishing, or irrigation with no waiting period . You won’t see signs that say “Do not swim for 3 days” because there’s nothing toxic in the water.
• Selective Control: A skilled operator can target specific areas and species. Mechanical methods are highly selective – the machine cuts exactly where you steer it . If there are patches of beneficial native plants, they can be left intact while removing the invasive clumps. This helps preserve habitat. You can also avoid sensitive zones (e.g. around nesting areas or sensitive mussel beds) by simply not cutting there.
• Immediate Results: The visual impact is instant. When a harvester passes through, you’re left with open water right away, not a week or two later. There’s no unsightly period of browned, dying weeds floating on the surface (often a side effect of spraying). Boat channels and fishing areas are cleared and usable the moment harvesting is done .
• Long-Term Benefits: Over time, repeated harvesting can actually reduce weed regrowth. Plants that are cut back regularly often become stressed, with weaker regrowth or smaller size . Lakes that implement annual harvesting often see overall plant biomass go down after a few seasons. Additionally, by preventing the accumulation of thick detritus layers, harvesting can slow the rate at which a pond fills in with muck .
• Use of Byproducts: What to do with tons of cut weeds? Instead of waste, the vegetation can be composted into a rich fertilizer or soil conditioner. Decaying aquatic plants from harvest make excellent compost, comparable to cow manure in nutrient content (and they contain no viable seeds by the time they’re harvested) . Some communities even give away or sell the dried, chopped aquatic weeds to local farmers or gardeners.

It’s worth noting that mechanical removal can be done at various scales. For small ponds or around homeowners’ docks, manual removal (rakes, cutters, or diver-assisted suction) can work as a low-tech option. Community volunteer days to pull water weeds might lack the high-tech appeal of a shiny weed harvester, but they can make a dent in small areas and raise awareness. For larger lakes or extensive infestations, mechanical harvesting machines or hydro-raking (essentially a floating backhoe rake that can scoop out weeds and sediment) are highly effective options. While mechanical methods do require investment, many municipalities are finding the ecological benefits outweigh the costs. Plus, as more companies offer aquatic vegetation services and equipment, the costs are gradually coming down.

Other Alternatives and Complementary Strategies: Mechanical control is a big piece of the puzzle, but it can be combined with other eco-friendly approaches for best results:

• Biological Control: In some cases, introducing natural herbivores can help keep weeds in check. Grass carp (a type of fish) are used in many states to eat excessive aquatic vegetation. When stocked appropriately (and usually sterilized so they don’t overpopulate), they can munch down weeds over time without chemicals. There are also insects specific to certain invasive plants (for example, weevils that eat water hyacinth or alligator weed). These biological agents typically won’t eradicate a weed problem, but they can be part of an integrated approach to suppress growth.
• Preventive Measures: The root causes of rampant aquatic weed growth often lie in what’s coming into the water. Nutrient pollution from lawn fertilizer, agricultural runoff, septic systems, or urban stormwater creates the perfect conditions for weeds and algae to explode. Tackling these sources is key. This might include promoting buffer strips of native plants around water bodies to absorb nutrients, improving sewage and septic management, and controlling fertilizer use in the watershed. While prevention doesn’t remove existing weeds, it slows down their return. Many lake associations are now combining weed removal with community education on nutrient management to achieve lasting change.
• Targeted Herbicide Use in a Supporting Role: It’s worth mentioning that not every use of herbicide must be all-or-nothing. Some of the most forward-thinking lake management plans use herbicides sparingly and strategically in combination with mechanical removal. For instance, a harvester can remove the bulk of biomass, and then a very minimal amount of herbicide might be used to touch up what little remains, or to target a few spots the harvester can’t reach (like near docks or rocky areas). In this way, herbicide use is dramatically reduced – no more blanket spraying of the whole lake – and the negative impacts are minimized. An integrated plan might harvest first and then do a limited, targeted herbicide application if absolutely necessary . The result is far less decaying mass left in the water and far fewer chemicals applied.

The bottom line is that we have the tools and knowledge right now to manage aquatic weeds without resorting to heavy glyphosate use. Mechanical removal, biological control, and nutrient reduction form a toolkit of safer, sustainable strategies. These methods treat the problem (too much weed growth) while avoiding creating new problems in the process. Yes, they can require more upfront effort and sometimes more cost, but the payoff is healthier water and communities – which is priceless in the long run.

Healthier Water, Healthier Communities

Switching to safer weed control isn’t just an abstract “environmentalist” idea; it brings tangible benefits to local communities and various stakeholders:

• For Homeowners and Lake Users: If you live by a lake or canal, you’ve probably seen the signs after a chemical treatment: “Do Not Swim” or “No Irrigation” for a certain number of days. With non-chemical methods, those warning signs vanish. Your family and pets can enjoy the water with peace of mind, not worrying about skin rashes or ingesting herbicides. The water will likely be clearer and cleaner, especially as recurring algae blooms subside over time. Property values around clear, healthy lakes tend to be higher than those around weed-choked or chronically algae-filled ones. Homeowners also won’t have to deal with foul odors from decay or ugly masses of dead plants washing up on shore – a common post-spray annoyance. Instead, any cut fragments from mechanical harvesting are collected, and the lake looks as if the weeds never invaded in the first place.
• For Power Plants and Utilities: Facilities like power plants, which often rely on canals or reservoirs for cooling water, have a vested interest in reliable, clog-free water flow. Aquatic weeds can be a nightmare for industrial water intakes, and while spraying might knock back growth, it can also result in mats of dead vegetation that drift and clog intake screens anyway. A robust mechanical weed management program can ensure continuous removal of debris before it ever threatens infrastructure. Some power companies have invested in their own weed harvesters or contracted regular harvesting services to keep intake canals clear. This approach not only protects the facility’s operations but also demonstrates environmental stewardship. It prevents the scenario of a plant inadvertently pumping chemically-laden water or decayed organic slurry through its system. In an age where companies are watched closely for environmental impact, avoiding chemical use can improve a utility’s public image and reduce regulatory scrutiny.
• For Public Works and Lake Managers: Local agencies responsible for parks, stormwater ponds, or city lakes can reap big rewards by adopting safer practices. Yes, budgeting for a harvester or contracting removal services might be a hurdle, but it can be presented as an investment in the community’s natural resources. Over time, the improved water quality can reduce other costs – for example, fewer fish kills mean less need for restocking, and better water quality might reduce water treatment costs if that lake feeds into municipal water. Public works directors will also avoid potential liability issues that come with chemical use (for instance, if overspray drifts into someone’s backyard or if a treated water body later violates water quality standards). By prioritizing environmental health, public agencies build trust with residents. There’s a growing public demand for greener solutions; when a city shifts from routine herbicide spraying to sustainable management, it’s often met with community support and positive press. In Florida, after public outcry over glyphosate spraying, the Fish and Wildlife Conservation Commission temporarily suspended aquatic herbicide use and started looking into more integrated approaches – a clear sign that agencies are responding to citizens’ concerns.
• Ecological Ripple Effects: Healthier aquatic ecosystems have their own ripple of benefits. When we reduce chemical inputs and excessive decay, water bodies can recover their natural balance. Fish populations thrive in oxygen-rich, plant-healthy environments – good news for anglers and the food chain. Birds and wildlife that depend on aquatic plants for habitat (like ducks or dragonflies) find more stable conditions when we aren’t periodically nuking their habitat with herbicides. Even downstream ecosystems benefit: cleaner lakes mean less polluted rivers and estuaries, contributing to broader environmental health (think of the fight against downstream problems like toxic algal dead zones in bays).

In summary, moving away from glyphosate spraying isn’t about letting weeds run wild; it’s about choosing smarter methods that create win-win scenarios – weeds get managed, and our waters get healthier. Communities stand to gain safer recreation, prettier lakes, and potentially even economic boosts from improved fisheries or tourism on a clean lake.

Choosing Clean Water Over Quick Fixes

The continued blanket use of glyphosate in our precious water resources is a classic case of short-term convenience versus long-term consequence. Yes, it’s easy to spray a chemical and watch the problem seem to disappear. But as we’ve uncovered, that convenience masks a slew of hazards – from algal blooms and fish kills to potential human health risks and costly environmental damage. With a known carcinogen being dumped into the very waters we swim in and drink from, it’s time to ask if the “cure” is worse than the disease.

The good news is we are not stuck with this trade-off. Homeowners, decision makers at utilities, and public works officials have the power to change course. It starts with awareness and the willingness to invest in better solutions. Communities can advocate for herbicide-free management of their lakes – many voices together can push local authorities to pilot new methods. If you’re a homeowner on a treated lake, talk to your lake association or county extension about non-chemical options; show them examples of other communities making it work. If you’re a public works director, consider allocating funds to purchase a weed harvester or partnering with neighboring towns to share equipment – collaborative regional solutions can make costs manageable. If you run a power plant, weigh the one-time cost of a mechanical removal program against the recurring expense and risk of chemical use – chances are, preventing intake clogs with regular harvesting will save money (and headaches) in the long run.

It’s also important to hold companies and regulators accountable. The fact that Bayer/Monsanto is paying out billions over Roundup® speaks volumes . We shouldn’t ignore that signal when deciding how to manage our local environment. While regulators may lag in updating policies, local jurisdictions can be proactive. Some towns have already banned the use of glyphosate on public lands. Water management could be next. Pushing for state-level or county-level restrictions on aquatic glyphosate use (especially in public waters) is a policy route to consider for concerned citizens and officials alike.

In closing, the spraying of glyphosate in lakes and ponds across the U.S. is a widespread practice – but it’s one we can and should phase out. We have safer, smarter alternatives at our disposal, and real-world examples have shown they work. By shifting our mindset from “weed killer” to “weed management,” we treat not just the symptom but the whole system, fostering water bodies that are resilient and healthy. It’s time to break the cycle of poisoning and pollution. Our lakes, our communities, and future generations will be better off if we choose clean water over the quick fix.

Sources:

1. North American Lake Management Society – Use of Herbicides in Lakes
2. The News-Press (Florida) – Example of Glyphosate Use on Lake Okeechobee
3. LakeMat (aquatic management company) – Drawbacks of Aquatic Herbicides (oxygen depletion and sediment)
4. Aquarius Systems (aquatic services) – Glyphosate and Algae Blooms in Lake Okeechobee
5. Aquarius Systems – Advantages of Mechanical Harvesting (nutrient removal, etc.)
6. U.S. Geological Survey – Glyphosate in Streams Study (widespread detection in water)
7. NPR News – Bayer to Pay $10 Billion in Roundup Settlement (125,000+ lawsuits, WHO classification)
8. Wisconsin DNR – Glyphosate Fact Sheet (environmental persistence and regulatory info)
9. Hamburg Township, MI – Aquatic Weed Control Program FAQ (cost of mechanical vs. chemical)
10. Aquarius Systems – Mechanical Harvesting Benefits (selectivity, long-term effects)
11. Aquarius Systems – Integrated Approach (Harvest then Herbicide)
12. Aquarius Systems – Composting Harvested Weeds
13. Aquarius Systems – Herbicide Suspension in Florida .