What is flocking?

Flocking is the term for clearing the water in a lake or pond by applying a mineral which attracts soil particles, and then allows them to sink to the bottom. The soil particles are attracted to or flock to the mineral due to the effects of positive and negative ions.

Flocking is an important part of lake and pond maintenance, but the cause of the turbid water should be dealt with, or the problem will return.

Bare banks and dams

There are several causes of soil sediments in lakes and ponds, and most of these can be resolved with the proper use of vegetation. Bare banks or dams allow sediment to be washed into the lake with rainfall. The erosion caused by this situation is another concern. The answer, is to get something growing on the bank. Grasses would be the best choice, but almost any low growing vegetation is better than the consequence of none at all. We caution against planting trees on lake and pond dams though. Trees produce large roots, and if a tree dies, the resulting rotting roots may provide a channel for water to escape, and possibly more severe erosion damage or even dam failure.

Sediments from off site

Plowed fields upstream from your lake can lose soil to erosion, which can eventually end up in your lake. Once again, vegetation is the key to controlling the problem. Planting a vegetative barrier at the mouth of your lake or pond will reduce the movement of soil particles, chemicals, and fertilizer into your lake.

Flocking materials

Flocking materials typically include alum, gypsum, or agricultural lime stone. They can all be effective. If you live in a high pH area, limestone might be your best bet, since it will allow you to kill 2 birds with one stone. Otherwise, the main consideration is cost and availability.

This is a list of questions we have received in years of dealing with lake management issues, and the answers deemed to be most appropriate. Aquatic weed control issues are almost like political issues, and in most cases they produce a lot of heat but very little light. In this, as in most issues, the key is balance. Some people believe that all lake weeds are good, some, that all lake weeds should be destroyed, the truth is, that some vegetation is needed, and some types of vegetation are not. These questions and answers should provide a good starting place for your aquatic weed concerns.

If you would like to ask a question that is not addressed here, feel free to do so in the comment section.

Question:

What is the best way to control aquatic weeds?

Answer:

The best way to control aquatic weeds is to prevent them from the start. Make sure that none are introduced to your lake, and make sure that your lake will not reproduce them, if they do find their way to you. Clean equipment, deep water, and good algae bloom are the best methods of preventing lake weeds, and are therefore, the best control method. See: Lake Management Lake Weed Control Water Depth Secchi Depth

Question:

Isn’t a little hydrilla good for bass fishing?

Answer:

This question is asked so often that I am thinking of making a form letter to answer it.

First off, any reasonable amount of cover makes bass fishing better. Any amount of hydrilla is bad. There are hundreds of other lake plants which will serve the purpose of bass cover better than hydrilla. Even if hydrilla was the best cover for bass, it would still be a mistake to use it. Hydrilla is invasive, and it can take over a lake in a matter of weeks if conditions favor it’s growth, a condition which will make fishing difficult, or impossible. Once you have it, it is notoriously difficult, and expensive to get rid of. The irony here is that people who try to make better bass fishing by using “a little hydrilla”, usually end up ruining their bass fishing forever!

Question:

I used the recommended chemical treatment for my lake weed problem, but the weeds are coming back. Did I do something wrong?

Answer:

The answer is both yes and no. No. If the chemical treatment took the weeds down, it did it’s job. Yes. Yes, you made an error of omission. You did not solve the problem which allows the weeds to grow in the first place. That problem is most likely either: Lack of plankton producing fertility, or your lake or pond is too shallow. No matter what method of weed control you use, if you don’t get rid of the cause, they will be back.

Question:

How much vegetation do I need for a healthy lake?

Answer:

The standard answer is around 20 or 25 %. There are a few variables. If all your vegetation is invasive, exotic vegetation, it would be best to get rid of all of it and start over.

Question:

Why do we need vegetation in the water at all?

Answer:

Vegetation provides oxygen for the water, and cover for fish.

Question:

Why did that green slimy stuff grow after the weeds died?

Answer:

The degrading weeds acted as fertilizer, causing an excessive amount of alge growth, this will not be a serious problem if everything else is brought into balance.

Question:

Won’t dyes color the water and keep the weeds from growing up?

Answer:

Yes, but they do not provide the food for the bugs that provide food for the fish, and oxygen for the water that fertilization will cause.

Question:

I have a lake full of weeds, but oxygen is low. Why is this?

Answer:

Weeds transpire oxygen, and use carbon dioxide to make it. This is good. Unfortunately they may re absorb oxygen at some points in the evening. They also restrict the flow of oxygenated water when there are too many present.

Question:

Why do I need to lime my pond?

Answer:

If the water has the proper pH, everything else you do to manage your pond or lake will work together, and work better.

Question:

Why do I need to get rid of my weeds before I fertilize my pond?

Answer:

To stop them from robbing the water of nutrients needed to produce plankton, which reduces light, which, in turn, reduces weeds. If you get rid of the weeds growing around your garden plants, your plants will outgrow the weeds, and eventually shade most of them out.

Question:

If I fertilize my lake, won’t that just cause more weed problems?

Answer:

No, not if done correctly. Ideally, the fertilization will encourage the growth of plankton in the water, which will shade the bottom, helping to prevent further weed problems.

Question:

Is all vegetation bad?

Answer:

Yes and no.

No, some vegetation in a pond is good, and is needed for providing oxygen to the water. People who practice chemical vegetation control are often accused of wanting to get rid of all vegetation in a lake or pond. This is patently false! It may be due to a misunderstanding. No one wants to kill everything.

Yes, aquatic weed control specialists would like to eradicate invasive exotics. We are talking apples and atomic bombs here. People  who say such things obviously do not understand the situation.

Mechanical lake weed control is the physical removal of lake weeds from the lake or pond. It is not merely weed removal by machine. These are some things you should think about before embarking on a mechanical aquatic weed control programs:

Mechanical lake weed control

1. Only use this method, particularly the mowing method, if you are resigned to the idea of mowing your pond or lake on a regular basis, just like mowing your lawn.

2. Use good equipment that will not fragment the weeds and cause replanting. The smoother the operation, the less the fragmentation. Using something that will shatter the lake weed into thousands of pieces, which makes collecting the fragments difficult, and not collecting them a bigger problem.

3. Gather all plant fragments from the water. Aquatic weeds are notorious for their ability to reproduce from fragments. Some species can reproduce from fragments at 50 percent or more. One plant could become more than a hundred fragments, which could in turn become half as many new plants, multiplied over thousands of plants, the result could be disaster!

4. As in all control methods, as long as the water color, or water depth remains the same, the weeds will recur. Try to do something about changing these factors. Wherever sunlight can penetrate to the bottom, weeds will grow. Lake Management Lake Weed Control Water Depth Secchi Depth
Lake Management Lake Depth Secchi Disk

For the best lake management, and lake weed control there are 2 often ignored keys, and they both have to do with the depth to which sunlight penetrates in a lake or pond.

If sunlight can not reach the bottom of your lake or pond, you will not have lake weeds. Aquatic weeds, like all other plants, cannot grow without sunlight. So, the key to stopping a lake weed problem is to prevent sunlight from getting to the bottom.

There are 2 issues to deal with: Water depth, and water color. Both are important.

Water depth

The deeper the water, the less sunlight reaches the bottom. To change the waters depth, you must either raise the water level, or lower the bottom.

Raising the water level

Raising the water level may be difficult, but it can sometimes be done, depending on several factors. If you have a strong dam, and the capacity to raise the level of the outlet, you can add some depth to your impound by doing so.

Lowering the lake bottom

If you can dredge the highest points in the lake or pond, this will lower the bottom, and, of course, make the water deeper. If the pond can be drained, earth moving equipment can accomplish this. If it cannot be drained, there are floating dredges and other equipment for the job. A combination of edge dredging, and raising the water level will often produce the desired effect.

Water color

The darker the water, the less sunlight reaches the bottom. Water color has a direct effect on the amount of sunlight which reaches the bottom of a body of water, and the less sunlight reaches the bottom, the fewer problems you will have with lake weed control.

Artificial colorants

There are colorants available to dye the water, but this is not the best way to manage a lake or pond, unless it is only being used for decoration, or for fed catfish. Artificial colorants interfere with the natural food chain. There is a better way.

Algae bloom

Single cell algae from the plankton family are naturally occurring plants which are suspended in ponds and lakes. If the fertility conditions are right, they will grow and remain suspended in the water profile, and their natural green color provides protection from sunlight. This plankton also provides food for the small aquatic animals which feed the bugs, which feed the small fish, which, in turn, feed the larger fish in the biological chain. Without this “circle of life”, the lake or pond will be little more than a holding tank.

Producing algae bloom

The trick to producing this algae, is to do something which might, on the surface, seem counter productive. Fertilize the lake! The rise in fertility will cause “algae bloom”, the algae will protect the lake bottom from sunlight, the weeds which always start at the bottom will not have sunlight, and the pond or lake will be relatively free of unwanted weeds.

Water pH

Before taking this step, check the pH of the water. A simple water testing kit will tell you the acidity level of your pond or lake. For the best results, pH should not be below 6.8. If it is below this mark, the pH should be raised by adding an alkaline source such as agricultural lime.

Aquatic fertilizer type

Fertilization should be done with a product high in phosphorous, and low in the other 2 chief elements. When you look at a fertilizer container, it will have 3 numbers, divided by dashes. phosphorous is the one in the middle. Most farm and ranch, or chemical supply places will have a fertilizer made for this purpose, complete with instructions on the amount to use, and the best method for application.

Duration

You will need to continue to apply fertilizer throughout the summer months, checking the Sechi Depth as you go. If light is penetrating past 18 to 24 inches, more fertilizer is needed, when light penetrates less than 10 or 12 inches, you should back off.

See also: Lake Management Lake Depth Sechi Depth

A “Secchi Disk” is a tool for measuring the depth to which light penetrates liquid. Since sight, is based on light, then the distance at which you can still see an object in liquid, is the depth that the light can penetrate that liquid.

In order to have a standard measurement for this, the secchi disk is used. The disk is an 8 inch disk with 4 alternate triangles of black and white. It is attached to a string, or pole, and the distance at which it disappears from view in a pond or lake is the secchi depth. Ideally, that depth would be 18 to 24 inches. A secchi disk can be purchased from lake supply dealers, but it is easy to construct one of your own. Mine is an 8 inch steel disk, painted solid black, with the white triangles painted on top of the black, and a hole drilled in the center to attach a rod. I chose to attach a landscapers measuring rod to mine, in order to be able to use the disk and measure the depth in one operation.

Secchi disk top veiw measuring stick attached

This secchi disk is homemade, and has served me well for years. Note the alternating black and white triangles, the measuring rod, and the mud on the the disk.

A side veiw of a Secchi Disk hooked to a measuring stick

This is the same secchi disk from a different perspective, and with the measurements visible.

Lake Management Lake Weed Control Water Depth Secchi Depth

There are several aquatic weed control types and methods.Prevention is always best, find out more about the others below.

Aquatic weed prevention

Lake weed prevention is the best form of aquatic weed control. This is true of everything from the flu to auto wrecks: Prevention is always better than control or treatment after the fact!

Aquatic weed control using prevention starts with clean equipment.

The very best method for controlling lake and pond weeds, especially those of non native origin such as Hydrilla, Water Hyacinth, Giant Salvinia, and many others, is to prevent them from getting a start in your pond or lake.

Methods of  aquatic weed movement

There may be some methods of trans-location which are beyond your control, such as water coming onto your property from other bodies of water upstream, or movement of animal life such as ducks, geese, cranes, and herons who could be carrying hitch hikers, but the highest percentage of exotic aquatic trans-location occurs through human help.

This can be intentional, such as planting some of those nice little blue flowers someone saw at another lake, or adding a little hydrilla for good bass cover. This is never a good idea. In the first place it is illegal, and in the second, those cute little flowers, or that nice cover for bass, could soon engulf your lake!

It can be unintentional, such as not cleaning your boat, propeller, trailer, live well, and other fishing gear after a trip to an infested lake. It is best to consider all lakes as though they are infested, and clean accordingly! While some public lakes do not have these problems, it is still a good idea to do a thorough cleaning before moving to the next location. You should also require anyone else boating or fishing on your private impound to do the same. These methods will not guarantee a lake free of exotic invaders, but they will help you to do all that is in your power to prevent them.

On the surface, biological aquatic  weed control seems like a great idea. It sometimes is. Biological control seems to be the “green” thing to do, but I have a few things that cause me to question this method.

Biological Aquatic Weed Control

• The controls are limited. There are a few weevils, that eat a couple of plants, there is an oriental fish that eats almost any vegetation, but so far, that’s about it.Although all sanctioned biological controls have been thoroughly researched by the top scientists in the field, things can still go wrong.
• Changing weather conditions, and interaction with other species over extended periods of time could bring about a completely unexpected chain of events, culminating with a new ecological disaster!
• If the new control is a natural enemy of the exotic plant we are trying to stop, and something changes, you now have two invasive predators in the environment instead of just one. What if the new entity decides it likes to eat sweet potatoes, corn, or soybeans more than what it was brought in to control?
• In most states, the only legal grass carp for controlling aquatic weeds, are sterile grass carp. This is because they consume so much vegetation, and having an extra one or two could lead to a lake devoid of any vegetation. Accidents can still happen. The accidental, or even intentional introduction of a pair of non sterile fish into our waters could spawn the cleanest, but deadest fishing lakes in the world. The escape of the sterile form into a river could do immense damage as well.
• If the lake weed problem is in the early stage, there is hope for eradicating it. Try using the chemical method early, and often until the problem is gone.
• Continue to use the chemical treatments for periodic maintenance, and make adjustments to the environment such as liming if needed, and fertilization. If aquatic weeds can’t get sunlight, they can’t grow. Proper fertility will help to keep the proper level of suspended algae growth.
• If mechanical lake weed control is needed, it should be done with the least disturbance possible, to limit fragmentation. The plants should be cut smoothly.
• The fragments should be harvested from the water. Every fragment is a potential plant, so remove them all.

There are other concerns as well, but in a completely controlled setting, the desired effect could be gained. We should exercise extreme caution when using this method.

Mechanic Aquatic Weed Control

Mechanic lake weed control is the physical removal of a plant, or part of a plant from the lake. One methods for controlling lake weeds is physical control. The cutting, harvesting, pulling, or rolling down of the weeds by mechanical means. Mechanical, or physical control is useful in several situations. Physical removal is not always a good thing. Many times, mechanical means fragmentation which can lead to problems.

Aquatic vegetative reproduction.

Exotic weeds, and even some native plants often reproduce vegetatively. This is just another way of saying that pieces of the plant can, and do develop roots, or feeding tentacles when broken away from the mother plant. This is especially true of aquatic plants.
Many lake and pond weeds reproduce from fragments at a rate of 50% or higher. Imagine this: If you have 1 hydrilla plant in your lake, and you chop it up into 100 pieces, the chances are very high, that you will have 50 of the fragments survive and take root. Multiply that by 1000, and you can begin to understand the problem!

Now, the use of mechanical controls can be good, and sometimes are the only means of bringing about a pond or lake that is clean enough for recreational use, but it should be avoided if possible.

Chemical aquatic weed control

Many people fear chemicals, but when it comes to aquatic weed control, it is often the best option for the pond or lake, and it is often the most environmentally sound method as well. If you choose to use this method of aquatic weed control, there are a few things you should know:

It is vital to follow label directions. In fact, it is a federal crime not to follow the label directions. There are contact herbicides, and systemic herbicides. Contact herbicides kill only the part of the plant that they contact. Systemic herbicides work through the plant to get to the root. They need sufficient chemical to contact the plant for sufficient time to have the maximum effect.

Many people who move from urban areas into semi suburban, or semi rural areas, buy properties which include elements with which they are unfamiliar. The cost for lake management can be a little surprising, but the cost of not managing a lake can be much higher!

Large pasture like lands which once served as grazing areas for cattle, have now become back yards. Stock tanks, or ponds once used for watering cattle and other livestock have now become recreational fishing lakes or ponds. In many cases, the new owners realize that they do not posses the information, or the equipment needed to maintain such amenities.

Mowing large areas repeatedly can become very expensive very quickly, but there are mowing alternatives which can help.

Lake management cost considerations

Ponds and lakes can present a somewhat different set of problems. Lake maintenance, like pasture maintenance can get a little expensive. Potential property owners should take this into consideration before buying. In most cases, maintaining an acre of water, will cost as much to maintain as an acre of  lawn, and such costs should be considered in the overall package.

What are these issues?

It would be a mistake to think that a lake or pond will take care of itself. It is a living organism teaming with living things, which will tend to get out of balance from time to time. Some things will grow there which might be alright if it were a body of water setting in the middle of nowhere, but not in your back yard. Getting, and then maintaining balance is your goal.

Aquatic weed control and lake management

Aquatic weed control will be the primary concern. Without it, the lake will become overgrown with vegetation, and all sorts of undesirable wildlife, including insects and rodents. Controlling aquatic weeds with herbicides, mechanical controls, or biological controls can be difficult and costly. Preventing their return through controlling water quality and water depth is the best alternative.

Water quality

One of the most important elements related to aquatic weed control, and lake management in general, is water quality. This both effects, and is effected by lake weeds. Maintaining proper pH and proper fertility helps to bring the cycle into balance. This involves testing the water, in most cases, correcting the pH will include the use of lime, fertilizing the pond or lake, or, if excess fertility is the problem, creating a vegetative buffer, or barrier to run off containing high levels of nutrients. The cost for this can be substantial.

Water depth

Water depth is another consideration related directly to controlling aquatic weeds. Weeds tend to occur in shallow water, and raising the water level, or dredging can be expensive.

Aquatic recreation

If the pond or lake is to be used for fishing, the cost for preparation and stocking should be taken into account. The same is true with other recreational activities, docks, boat houses, and other additions may be needed.

Lake maintenance costs

At this time, and in this location, the cost of caring for an acre of lawn per year is estimated by various state agencies as about $2,600.00 per year on average. Our experience has been that this is similar to the cost of maintaining an acre of water, although there are occasional spikes in activity which will raise the cost a bit. This should help those who might be in the process of considering a property with a lake or pond, or those already in possession of such properties to count the cost of lake maintenance in the overall property maintenance cost.

Caddo Lake

Aquatic weeds can be a huge problem for the property owner. If you use your lake primarily for recreational activities, lake weeds can put an end to your fishing, and other water sports in a matter of weeks if the wrong conditions exist. A lake weed invasion can also cause other problems, like pests in general, and mosquitoes in particular.

What is the best way to handle lake weed problems?

That depends on the nature of the problem. If the problem is an overly fertile body of water, you will need to lower the fertility.

Too much fertilizer

Excess fertility can be caused by nutrient runoff ending up in your lake. These nutrients can come from agricultural sites like adjacent farms and ranches existing upstream from your lake, or from over fertilized lawns in your area, which could even be your own.

Low fertility.

Low fertility means that the pond or lake is not getting the nutrients it needs to produce plankton. If plankton is not produced in sufficient quantity to tint the water enough to keep light from penetrating to the bottom, light will reach the bottom, and plants will grow up from it. This includes the filamentous algae that is often seen floating on a lakes surface.

Shallow lakes

Is your pond or lake so shallow that lake bottom gets light, weeds will grow. The best way to solve this problem is by either raising the water level if possible, or dredging.

Weed types

You should also know which category your lake weeds fall into. Are they submersed, emergent,  floating, or algae. There is a difference when it comes to treating them. There is a great tool from Texas A & M to help in the identification process. It is called Aquaplant. Aquaplant is also an excellent example of what a website should be!

Methods of aquatic plant control

Prevention:

This is the very best method for controlling any situation. If you can prevent it, you won’t have to control it or manage it in other ways. It just makes sense.

Biological control:

Most environmentally aware individuals prefer biological controls to chemical controls. There are some problems with that idea. Biological controls can be unpredictable, and run the risk of getting out of control if conditions should change. After all, you are adding another invasive predator into the mix!

Mechanical control:

Mechanical controls are great for some aquatic weed work, but not for all. Many aquatic weeds can reproduce from fragments at rates higher than fifty percent!

Unless you are resigned to mowing your lake as you do your lawn, it is a bad idea to fragment the living plants. If they can be cut smoothly, without much fragmentation causing vibration, and completely collected , that is great, but the problem will return from the roots.

Chemical Controls:

Sometimes, in fact, most of the time, the best weed management method, the most eco friendly method after prevention, is chemical lake weed control. It can, and should be, selective.

Aquatic weed control chemical types

Chemicals for controlling and managing aquatic weeds, fall into two categories:
Contact, and Systemic.

Contact Herbicides

Contact herbicides, work quickly, and kill all the vegetation they touch.

Systemic Herbicides

Systemic herbicides, work more slowly, but travel to the root of the plant to kill all parts of the plant.
Which one should you use? That depends a lot on the conditions, and the plant you are trying to get rid of. For more information on lake weed control types see:

Lake Weed Prevention

Biological Lake Weed Control

Mechanical Lake Weed Control

Chemical Lake Weed Controls