5 Lake Restoration Myths
When lakes are in trouble, communities search for solutions. Lake associations ask:
- What exactly is wrong with our lake?
- What’s the best solution?
- Who should we believe?
Communities become vulnerable to what we call “restoration” myths. Myths are common stories told about solutions that may or may not be truly restorative. In our experience there are 5 myths about lake restoration. Within every myth lies some truth, but when it comes to restoring a lake to optimum health – and sustaining long-term health – it’s important to distinguish between fact and fiction.
Our job is to make sure lake communities are aware of the difference. The lake depends on it and so do the people who depend on the lake.
These 5 myths are “people management strategies” and not authentic lake restoration solutions.
- Expensive studies are necessary.
- Chemical herbicides will restore the lake by killing weeds.
- Aluminum sulfide will restore the lake by reducing blue-green algae.
- Dredging will restore the lake by removing lake-bottom muck.
- Watershed management alone will resolve nutrient overloading.
Myth #1: Study, Study, $tudy
There’s no doubt that lake-data is important. Unfortunately, it is not uncommon for consulting firms to charge tens of thousands of dollars or more to develop a lake management report. The reality is that the bulk of the information in a typical 100+ page report is historical information on the formation of your lake which includes boilerplate material that can usually be obtained for free with a handful of Google Searches.
The critical data on dissolved oxygen; nutrient levels and sources; and sediment composition can be obtained for a few thousand dollars in lab tests. Often, it may be even be possible to work with a local university or college to do the testing, data analysis, and report development for little to no cost to the lake community. The myth that exhaustive and expensive lake studies produced by experts are required to restore a lake is just not true.
The impact of the “Study, Study, Study” myth is that tremendous economic resources are being consumed to develop a “glossy report” instead of invested in actually improving the condition of the lake. Worse, at least in our eyes, is that when it comes to actual management/restoration recommendations, these expensive reports often rely on traditional symptom-treatment management strategies that don’t solve the problem of nutrient overloading and are prohibitively expensive short-term fixes.
Here are just two examples of the Study, Study, Study, myth.
- On an 8 acre Midwest Lake – $45,000 was spent on a study to conclude that the lake was impaired by nutrient overloading. The report recommended spending $1 million on a dredging project.
- On a 1000 acre Midwest Lake – more than $200,000 was spent on a study that concluded their lake was nutrient overloaded. This study recommended a $25 million dredging project.
These are just two of hundreds of examples of excessive fees paid for “advice.” Worse, the recommendations made did not suggest technologies that actually dealt with the problem – nutrient overloading. Their “solutions” treated the symptoms, but not the cause.
Myth #2: Chemical Herbicides Will Fix the Problem
There’s no doubt that chemical herbicides kill weeds. It’s fast and produces dead weeds. But chemicals don’t restore the lake. They don’t resolve nutrient overloading. In fact, herbicides actually contribute to the problem.
First, when poisoned weeds fall to the bottom of the lake, those weeds become part of the compost pile that fuels further weed and algae growth. Dead weeds make more weeds and algae growth.
Second, when dead weeds layer the lake-bottom and add to the compost pile, their decomposition increases the demand for dissolved oxygen. Lack of dissolved oxygen is the problem in the first place. Decaying weeds only add to the problem. Worse, as the demand for dissolved oxygen is increased, anaerobic bacteria have the opportunity to overtake aerobic bacteria. It’s a lose-lose situation.
Third, certain weeds develop a resistance to chemical herbicides meaning that more herbicide treatments – and more powerful herbicides – need to be continuously applied each year. The cost of applying herbicides increases over time.
What all this means is that chemical herbicide treatments are not sustainable. They don’t reverse nutrient overloading. They don’t “restore” the lake. They don’t restore the lake’s ability to continually restore itself on an ecosystem level. They treat the symptoms of weed growth…but do not give the lake what it truly needs to get healthy. Be wary of experts who sell chemicals as a long-term solution. In our experience they work against nature…instead of with it.
Myth # 3: Alum Treatment Offers Long-Term Nutrient Control
Alum treatment is often the “go to” strategy for moderate to severely impaired lakes caught in the grip of toxic algae growth. Alum works by binding phosphorus in the water column and converting it into an aluminum phosphate compound that cannot be used by algae or weeds as food. As the alum settles to the bottom of the lake, it forms a “cap” that can absorb additional phosphorus as it is released from the sediments below.
While there is no doubt that alum can bind to phosphorus and make it unavailable to algae and plants, there is considerable scientific doubt about how long an alum treatment can continue to deliver benefits to a treated lake. Many “experts” tout a 10 to 20 year benefit from a single, properly applied alum treatment.
The reality is that alum treatments most often deliver a benefit for fewer than 5 years with some lakes experiencing pre-treatment algae blooms in as little as 2 years after treatment. Beyond debates on how long alum treatments can last, there are more fundamental questions lake associations should consider before moving ahead with an alum program.
First, the cause of internal loading of phosphorus in lakes is its release by decaying lake-bottom muck and a lack of dissolved oxygen at the lake-bottom. The phosphorus that binds to the alum stays in the system. There are a number of University studies that indicate that this “locked” phosphorus can be re-released into the water column in as quickly as two years after the initial treatment. Equally important, alum treatments do nothing to reduce the other main nutrient critical to plant and algae growth – nitrogen.
Rather than mitigate the impact of phosphorus loading with alum, why not treat the root cause itself by restoring the oxygen balance to the lake? Lack of dissolved oxygen is the cause. Restore dissolved oxygen, aerobic bacteria and diatomic growth and phosphorous is diverted to fish growth instead of weeds and toxic algae. That’s nature’s way.
Second, studies have shown that aluminum sulfate can be toxic to fish and other aquatic life. While buffered alum has been “deemed” safe, long-term impact studies have not been conducted. Is this a risk worth taking?
Finally, alum treatments cost an average of $3,000 to $4,000 per acre at recommended application rates. Given the track record of less than 5 years of benefit, over a 10 to 15 year period alum treatments are typically much more expensive than using laminar flow inversion and biological acceleration – which actually decreases in cost over time.
Alum is a mitigation strategy at best – not a true restoration strategy for improving the long-term health of your lake. To be quite blunt, alum treatment is like putting on a clean shirt when what you really need is a shower!
Myth 4: Dredging Solves the Problem by Removing Lake-Bottom Muck
There’s no doubt that dredging can deepen a lake by removing muck mechanically. This comes at an enormous cost and involves regulation by the EPA. The EPA has very strict guidelines about the disposal of dredged sediment. This alone should warn people. More important, dredging doesn’t solve the problem of nutrient overloading on a biological level.
Dredging releases pollutants, chemicals, PCBs, phosphates, nitrates and a range of other nutrients back into the lake’s water column. It’ll give you a deeper lake and remove muck mechanically, but in a few lake seasons excess weeds, algae and muck will return because the lack of dissolved oxygen on the bottom of the lake will not be resolved. Nature will take its course and it’s just a matter of time before weeds and algae will reappear and muck will continue to build. From our perspective, the millions of dollars spent on dredging should go toward fixing the problem of nutrient overloading.
Myth 5: Watershed Management is The Only Answer
It is absolutely a fact that an aggressive watershed management program should be a cornerstone of any successful lake restoration program. Reducing and controlling nutrients entering the lake is vital to the long-term health of any lake. HOWEVER, it is important to recognize the two critical limitations of watershed management efforts.
First, even the most well-conceived and executed watershed management plans struggle to achieve significant reductions in non-point source nutrient pollution. Controlling the behavior of all the individuals, agriculture and industries in a watershed that contribute to external nutrient overloading is extremely difficult politically and very expensive.
Second, in most impaired lakes the internal “compost pile” built-up over many years on the bottom of the lake delivers more weed and algae growth on an annual basis than run-off from the surrounding watershed.
We are highly supportive and contribute to building successful watershed management. But our goal is to restore the lake’s ability to respond to the increasing impact of human development. The only way to do that is to give the lake what it needs on a biological level. Give the lake what it needs and nature does the rest.