What aquatic plants may be found in a pond?
Aquatic plants fall into four functional groups with similar characteristics:
- Algae - Simplest plants that are microscopic (plankton) or have single or branched filaments (filamentous). Some forms of algae are attached to the bottom, have branched stems, but no true leaves.
- Submerged aquatic vegetation - These plants have stems and true leaves. Almost all the plant is submerged. Sometimes submerged plants have a few floating leaves and reproductive structures at the water surface.
- Floating plants - Plants that have most of their leaves and flowers floating on the water surface. They range from watermeal and duckweed (tiny floating plants) to water lilies.
- Emergent plants - Sometimes called wetland plants, they are rooted in water or moist soil and have most of their stems and leaves extending above the water surface. Cattails are a good example of this category of plants.
My pond is covered with green slime or stringy "moss." What is it?
Look closely at the plant material. If the water is tinted green, green-blue or possibly even brownish, then your pond is probably experiencing a planktonic (free floating, microscopic) algae bloom. These blooms usually consume available nutrients and run their course. A foul odor sometimes accompanies the bloom.
If the plants do not contain leaves and are stringy filaments, clumps or netlike masses, then one or a number of the species of filamentous algae are present. Filamentous algae usually start growing on the bottom, form mats that can float to the surface, and can eventually cover the entire surface of the pond.
When are algae or other aquatic plants a problem?
When aquatic plants impair the use of a pond, they become a nuisance and are a problem to you. Plants produce oxygen by day and consume it in respiration at night. Extremely dense growths of aquatic plants can cause excessively low oxygen levels early in the morning, which could affect fish or other aquatic life. Excessive submerged plant growth can isolate prey from predatory fish, which can cause a stunted or overabundant forage fish population.
How can I control algae?
In general, persistent algae problems involve nutrient loading in ponds. Control measures without nutrient reduction are usually only temporarily effective. Examples of nutrient reduction are exclusion of manure and fertilizers, elimination of sediment, and decreasing overabundant ducks and geese. Algae in small ponds or isolated areas can be manually removed with nets, screens or rakes.
Triploid grass carp are sterile, plant eating fish. These fish prefer submerged leafy vegetation and some floating vegetation like duckweed, but will eat filamentous algae in the absence of preferred food. They may provide some measure of control and require a permit for introduction into a pond. A Triploid Grass Carp Permit must be obtained from the Pennsylvania Fish and Boat Commission before triploid grass carp can be purchased or stocked.
Chemical control of algae requires a Permit For Use of an Algicide, Herbicide or Fish Control Chemical in Waters of the Commonwealth. Application and instruction forms are available online. The algicide chosen must be registered with the U. S. EPA and labeled for aquatic use. This permit has no fee and is reviewed by the Fish and Boat Commission and Department of Environmental Protection. Ponds without an overflow can be treated with a dye, which blocks light penetration into the water, inhibiting algal growth. The other family of algicidal chemicals uses copper as the active ingredient, for example, copper sulfate. Great care must be exercised with these chemicals since copper can be toxic to nontarget aquatic life, especially trout. Also, chemical control of heavy algal growth may lead to oxygen depletion from decaying algae, which could result in a fish kill.
A final option that has some scientific basis, but is not regulated is the use of barley straw. Straw from barley in particular has been found to produce an unknown algicidal chemical when it decays. Use of one to two bales of barley straw per acre, broken up and placed in mesh bags, often controls algae satisfactorily. This procedure is not regulated by permit. Avoid using too much straw since it will use up oxygen in the decay process.
How do I control "seaweed," or submerged aquatic vegetation?
A more accurate identification of the plant in question is necessary before control is achieved. You may find the following booklet to be helpful in identifying your problem plant: Pond Management and Aquatic Plant Control, available through the Penn State Publications Distribution Center (814-865-6713).
More publications available at the PSU Pesticide Publications page.
Manual harvesting of submerged plants can occur. Removing plant fragments is important to prevent plant reproduction through fragmentation, which could make plant beds even more extensive. Harvesting also takes some nutrients out of the pond, much like bagging grass clippings from a lawn.
Triploid grass carp, a sterile herbivorous fish, prefer submerged aquatic vegetation. They can live for more than 10 years and provide a variable level of control, depending on the type and density of plants. A Triploid Grass Carp Permit must be obtained from the Pennsylvania Fish and Boat Commission before triploid grass carp can be purchased or stocked in your pond.
Chemical control of submerged aquatic vegetation can occur if the pond owner has obtained a Permit For Use of an Algicide, Herbicide or Fish Control Chemical in Waters of the Commonwealth, and uses a herbicide that is EPA registered and labeled for aquatic use. Application and instruction forms are available online. This permit has no fee and is reviewed by the Fish and Boat Commission and Department of Environmental Protection. Commonly used chemicals are presented in the Penn State/Fish and Boat Commission publication Pond Management and Aquatic Plant Control, available through the Penn State Publications Distribution Center (814-865-6713).
More publications available at the PSU Pesticide Publications page.
For any herbicide use, it is critical that you read and follow the product label. Commonly used herbicides for submerged aquatic plants are Reward, formerly known as Diquat ®, Aquathol-K ®, Komeen ®, Sonar ® and various forms of 2,4-D.
Remember that chemical control of plants leads to their decay. Lack of oxygen from plant decay is the most common cause of fish kills in treated ponds. Also, nutrients from chemically controlled plants killed are released into the water and may trigger an algae bloom or additional plant growth.
What types of emergent plants cause problems?
Three emergent plants are almost always the target when emergent plant control is desired, primarily because their ability to take over a shallow water/wetland area. These plants are phragmites, or common reed, purple loosestrife and cattail. These plants often encroach on a boat launch area, and in the case of phragmites and purple loosestrife, invade and crowd out native plants in a wetland, which reduces the wetlands's value to animals using it. A Permit for Use of an Algicide, Herbicide or Fish Control Chemical in Waters of the Commonwealth is required if the control area contains water.
The most commonly used chemical for emergent plants is Rodeo ®.
What problems can be encountered with floating plants?
Floating plant problems usually take two forms:
Can lowering the water level control plants?
This practice, termed "draw down," can dry out and provide partial control of plants in the dewatered area. It is particularly effective when done in association with freezing weather. If you draw a pond down after turtles, frogs and salamanders begin hibernation in the mud and this mud is exposed, chances are that these hibernating creatures will be killed. If your pond is larger than 1 acre, you must apply for a Pennsylvania DEP/Fish and Boat Commission Permit to Draw Off Water From Impoundments because release of larger amounts of water is a regulated activity. This application is available on the PFBC website.
What is the process to obtain a Permit For Use of an Algicide, Herbicide or Fish Control Chemical in Waters of the Commonwealth?
The person or group responsible for the lake or pond must complete a permit application and send it to:
Pennsylvania Fish and Boat Commission
Division of Environmental Services
595 E. Rolling Ridge Dr.
Bellefonte, PA 16823
An application may be obtained from this address or online.
The Fish and Boat Commission (PFBC) reviews the permit for completeness, correctness of chemical choice for the plant to be controlled, appropriateness of the dose and treatments proposed, potential non-target impacts in the water body and downstream, and potential impacts on recreational users of the water body.
The application is sent to the Department of Environmental Protection (DEP) - Bureau of Water Supply Management for review of chemical choice and dose, and potential impacts on drinking water supplies. When the applicant receives a permit signed by both PFBC and DEP, the approved treatment can occur.
What is a draw down permit? When do I need one?
A draw down permit, more formally known as a Permit to Draw Off Water From Impoundments is a permit that regulates release of water from dams, ponds or impoundments in certain situations. It is a permit jointly reviewed by the Department of Environmental Protection - Division of Dam Safety, which looks at structural and safety issues, and the Fish and Boat Commission, which reviews environmental and recreational impacts in the impoundment and downstream. The permit has no fee associated with it.
Draw down permits are required for:
- Water bodies with a surface area that is greater than one acre; and
- Water bodies of any size that require another state permit, for example a DEP Dam Permit or a Waterways Obstruction and Encroachment Permit for the proposed project.
If you are considering dredging or activities that could affect wetlands or streams, it is important that you contact the Department of Environmental Protection Regional Office serving you to review what activities are regulated. A draw down permit application is to be submitted at least 30 days before a draw down event is to occur.
Can I build a pond on my property?
You may be able to build a pond on your property if you first determine what permits may be required. It is possible that a Waterways Obstruction and Encroachment Permit may be needed. Contact your County Conservation District as the first stop. The Conservation District can also assist you with any erosion and sedimentation requirements that you should have in place during construction.
A second contact is the regional office for your area of the Department of Environmental Protection if you cannot get definitive information from the Conservation District.
The best guide for constructing a pond that we have encountered is the U. S. Department of Agriculture Handbook 590 entitled Ponds: Planning, Design, Construction.
You can also get a great deal of information from the Penn State/Fish and Boat Commission pond website.
I want to purchase fish for my pond, can you tell me where I can buy them?
Commercial Propagators (legally authorized to sell fish), are regulated by the Department of Agriculture. A list of propagators is maintained by their Aquaculture Program, 717-772-2852.
Two other contacts:
- Pennsylvania Aquaculture Association, 717-866-2461
- Pennsylvania Trout Farmers Association, 814-445-5427
Note that only certain species can be stocked. View fish species that can be legally introduced into PA waters on our Species Approved for Propogation listing.
Pond Management Resources
Penn State has an excellent site that is a collaborative effort between Penn State Cooperative Extension and the Commission. The goal of that site is to provide educational resources on proper management of ponds in the areas of aquatic plants and algae, fisheries, pond structure and water quality.
Two readily available publications may also be helpful:
- The Penn State University College of Agricultural Science and the Fish and Boat Commission cooperated to produce a 22 page booklet entitled Pond Management & Aquatic Plant Control. Subjects covered include construction, maintenance and management of a pond, types of aquatic plants, and management alternatives for plant control. It includes color photos of common aquatic plants. The booklet is available through your Penn State Cooperative Extension County Office or the Penn State Publications Distribution Center (814-865-6713). More publications available at the PSU Pesticide Publications page.
A second publication entitled Management of Fish Ponds in Pennsylvania is also available at no charge from the Penn State Publications Distribution Center. This 30 page booklet summarizes pond construction, maintenance, water quality, fisheries, and aquatic plants and algae.