5 Factors to Consider When Controlling Aquatic Vegetation

Plants are often an essential component of many aquatic environments. However, in many instances aquatic vegetation, especially in excess, can prove detrimental for a variety of reasons. When you’re controlling aquatic vegetation, it’s important to remember that the most effective methods to use will depend on a number of factors.
1. Type of Water
Water that is static will require different methods to control vegetation than water that is flowing. The Virginia Cooperative Extension states that dredging and deepening is an adequate method of controlling vegetation in a shallow pond. Herbicide application can also be successful in smaller bodies of static water.
Flowing water may require other methods such as mechanical or biological treatments. If there are any chemicals in flowing water, it’s often recommended to use herbicides that can be absorbed quickly, and to apply them during times of minimal wind. You should make sure to use herbicides that are deemed environmentally safe.
2. Weed Identity
Different types of weeds will not respond in the same way to each type of treatment method. If algae are the type of vegetation that needs to be eliminated, you should focus on nutrient reduction using phosphorus. There are a variety of methods that can be used to control the level of algae, including chemical, biological and mechanical.
There are certain weeds that may only be totally eradicated by the use of chemicals. According to Purdue University, completely removing cattails using mechanical methods such as raking is difficult. If the goal is total elimination of all vegetation, stocking the pond or lake with Grass Carp is a method of biological control that can be highly effective. However, if there are only certain types of vegetation that you want eliminated, another option should be considered.
3. Water Temperature
In general, aquatic vegetation will flourish in warmer water temperatures. In colder bodies of water there is normally less vegetation and mechanical methods may be enough to eliminate unwanted weeds and plants. Removing plants by hand once or twice a year may be enough to maintain the beachfront area of a Wisconsin Lake because the water temperatures will remain relatively low for most of the year. For a lake or pond in Florida, however, hand-pulling would have to be done often enough that either a biological or chemical method would prove more practical.
4. Types of Fish in the Water
If there is a large amount of wildlife in the water, mechanical methods are normally not the best option for removing vegetation. Mechanical methods can easily disturb sediments and smaller fish and turtles may be negatively affected. According to the Southern Regional Aquaculture Center, most aquatic herbicides are not dangerous to fish. However, it’s important to take precautions regarding the types of fish in any given body of water. One possible solution when using chemicals is to treat only portions of the water at a time, allowing fish to temporarily move to other areas.
5. Recreational Use of the Water
It’s also necessary to determine how the water is used before selecting a method of removing and controlling vegetation. Water manipulation, such as drawdowns, is not a good choice, especially in summer months if the water is used for swimming, boating and other recreational activities. Biological methods may upset the balance of fish populations if the water is used for fishing. There are a variety of chemicals that can be safely used in water where fishing and swimming take place. It should be noted that many chemicals have restrictions for a brief time after the herbicides have been applied.
Each of the previous factors need to be considered when deciding on the best method to control aquatic vegetation. After you’ve decided what method will work best you’ll need to make sure you’re familiar with the state and local laws in your area.