Many people become quite concerned when they see aquatic plants being controlled with herbicides in Florida waters. Their concerns seem to focus in two areas.

First, many believe that all aquatic plants in Florida waters are beneficial to the environment, not realizing that many of the plants they see are not native to Florida, but are invasive exotics which are quite harmful.

For more information and a nationally recognized definition of invasive species, see page 3 of this Executive Summary (published by the National Invasive Species Council). For more information about the "white paper" that was originally created by the Invasive Species Advisory Committee (ISAC), see this link.

Second, there are many who believe that the use of any herbicide must be damaging to the environment. They do not understand that not only are some herbicides safe to use when properly applied, but also that the failure to keep invasive, exotic aquatic plants under control would be devastating to the environment, public health and property.

The Bureau of Invasive Plant Management, in the Florida Department of Environmental Protection, administers a program involving state, federal and local governments which is designed to ensure statewide management of invasive aquatic weeds and to protect Florida's valuable natural ecosystems. This program recognizes the important roles native aquatic plants play in aquatic and wetland ecosystems, and these native plants are not the target of control activities except in those rare instances where they create problems for navigation, flood control, or other public welfare considerations.

This program is focused on bringing invasive, non-indigenous (exotic) aquatic weeds under what is called "maintenance control." Noxious aquatic plants are those which have the potential to hinder the growth of beneficial aquatic plants, to interfere with flood control, irrigation or navigation, or to adversely affect the public welfare or the natural resources of this state.

Maintenance control is Florida's working philosophy for managing noxious aquatic vegetation such as water hyacinth and water lettuce: plants which cannot be eradicated, plants which are here to stay. To understand what maintenance control is, it might be best to first understand what it is not.

WHAT MAINTENANCE CONTROL IS NOT
First, maintenance control is not allowing our lakes or rivers to become completely covered with noxious, aquatic weeds. Letting noxious aquatic weeds take over a waterbody may not only render it unusable for recreation or fishing, but may also displace desirable native plants, adversely affect fish and wildlife populations, and interefere with uses such as flood control, irrigation and potatble water supply. Maintenance control also is not allowing certain aquatic plants to build up to levels which provide habitat for disease carriers such as some species of mosquitoes, or to present other health and safety dangers to the public.

These examples, if allowed to occur, would be considered "crisis" management. When you see the workers out managing noxious, aquatic weeds, they are normally conducting "maintenance control."

WHAT MAINTENANCE CONTROL IS!
Florida law defines maintenance control as "a method of control in which techniques are utilized in a coordinated manner on a continuous basis in order to maintain the plant population at the lowest feasible levels" as determined by the Department of Environmental Protection. In every day language, that means maintenance control is a systematic, planned approach for controlling undesirable (noxious) aquatic weeds. The specific goals and objectives of each management plan are developed through interagency coordination and public input.

WHAT DOES IT MEAN TO THE PUBLIC?
This concept is not new or unusual. Anyone who maintains a car, or a lawn, practices the maintenance control concept. Preventive maintenance on your car means you frequently spend small amounts of time and money to prevent major breakdowns or repairs which can cost you many more dollars and the loss of the use of your car in future years.

As for your lawn, one would not allow the grass to become too tall, or allow weeds or some lawn pest to kill it, before taking some corrective action. Maintenance control prevents damage to the lawn and limits the time, effort and money necessary to keep it an inviting and useful lawn.

GOALS OF MAINTENANCE CONTROL
There are many goals in the maintenance control of noxious aquatic weeds which are common to all properly planned and conducted management operations. These include:

Less environmental damage caused by undesirable aquatic weeds
Most of the aquatic weeds which cause severe problems are from other countries and have characteristics which allow them to become serious problems in Florida's semitropical, shallow, and nutrient rich waters. For example, in Florida, water hyacinth populations can double every 7-14 days, because they have no natural enemies here. These plants can out-compete and displace our native plants, adversely impacting both fish and wildlife habitats. When left unmanaged on Lake Okeechobee, water hyacinth displaced our native bulrush and shaded out native submersed plants, plants which are important habitat for fish, waterfowl, and other animals; water hyacinth infestations interefered with the nesting and feeding habits of the endangered Everglades kite as well.

Water hyacinth and other noxious plants left unmanaged, or controlled only on a "crisis' basis, accelerate the changing of a lake into a marsh. Research at the University of Florida has shown that water hyacinth can add up to 4 times more organic sediments to our waterbodies when managed on a "crisis" basis than when managed on a "maintenance control" basis. This is because these plants naturally shed large quantities of plant material into the waterbody, just as trees shed their leaves in the fall. Think about a yard in which the leaves are never raked. The dead leaves can build up so that grass and other plants can't flourish. Noxious aquatic plants have similar effects on our waterbodies and beneficial native aquatic plants.

This organic material deposited in our waterbodies also has another "invisible" impact. Organic material in waterbodies decomposes, or rots, just as it does on land. This process consumes the "dissolved oxygen" which is present in the water. In water, only small amounts of oxygen are present, usually in the 3-9 parts per million range. Fish usually require 4-5 parts per million. Research, and many years of experience, has shown that unmanaged noxious aquatic plants can overload the system with organic material. When combined with other factors which naturally reduce the oxygen content of water (warm temperatures, cloudy days, and heavy rains) dense plant populations can further reduce the level of oxygen in the water. This stresses fish and, in severe cases, can cause fish kills. Maintaining low levels of noxious aquatic weeds reduces this oxygen demand and allows oxygen to be regenerated by interchange with the air, and by allowing sunlight to reach other plants such as algae which produce oxygen in the water. On the other hand, spraying plants on a "crisis" basis (after they have grown out of control) can work to reduce oxygen levels.

Crisis management	Maintenance control

With fewer noxious plants present, it is also easier for aquatic plant managers to control the weeds. Under these conditions there is less likelihood that nearby beneficial aquatic plants will be adversely affected.

Greater use of our waters
Our lakes and waterways are wonderful sources of recreation, aesthetic beauty and economic value. As long as society demands that our waterbodies be preserved and managed for the public good, noxious aquatic weeds which interfere with navigation, flood control, recreation, and destroy fish and wildlife habitat, will have to be managed. Due to the prolific growth rate of the noxious aquatic weeds which create problems, the fewer the noxious plants left, the less the adverse impact on water use. Of course the type and amount of plants which are allowed to remain may vary, depending on the need for habitat for fish and wildlife, the public's use of the waterbody, and the characteristics of that waterbody. Consequently, more plants may be present on some waterbodies than on others.

Crystal River boating

Wakulla Springs swimming

Use less herbicide
While the use of herbicides in our waters is controlled by the U.S. Environmental Protection Agency, the Florida Department of Agriculture and Consumer Sciences and the Florida Department of Environmental Protection, one must realize that any chemical can be dangerous when it is not properly used. In Florida, no herbicides are allowed to be used which are not properly "labeled" for use in water -- that is, no herbicides are allowed to be used which have not been specifically tested and approved for use in water, and that the approval is printed on the herbicide label. See the EPA's pesticide registration page.
See the Florida Department of Agricultural and Consumer Services registration page.

The aquatic plant management program is even more restrictive in that a determination is made for each site, and for each plant species targeted for control, as to which herbicide will be permitted for use. The herbicides permitted are those that have been determined to have the least potential for adverse effects on the public health, safety, and welfare, as well as on fish, wildlife, and the environment.

The method of application is also controlled to insure that impact to native non-target plants will be minimized. And the Department of Environmental Protection requires that public notice of the use of herbicides be given when the label contains water use restrictions. Added restrictions apply when any treatment takes place in the vicinity of potable water intakes.

Lower all costs
Airboats are often seen on the state's waterways managing aquatic plants. It is sometimes assumed that hundreds of gallons of herbicide are being added to the water. The truth is, usually less than one percent (1%) of the spray seen is an active ingredient. Most of what is seen is the water with which the herbicide is mixed. Research is constantly going on to improve treatment techniques to insure the smallest amount of herbicide necessary is all that is used for control. Studies of aquatic plant management on the Suwannee River show that maintenance control requires the use of much less herbicide to manage noxious plants at a low level, than it does when such plants are allowed to proliferate without control. This also translates into a much lower cost on an annual basis.

Think about it. Not as many noxious plants are present, less plants are sprayed, less herbicide is used, less labor is required, and costs are greatly reduced. That is what maintenance control is all about. There are many other examples, such as the St. Johns River, Lake Okeechobee, even small lakes and ponds, where this approach has shown the same success.

Tailor treatments according to each waterbody
Each waterbody, and each noxious aquatic weed problem, have unique characteristics. By keeping the target noxious plants at a low level, it is possible to make allowances for fish spawning seasons, waterfowl or wildlife migrations and nesting patterns, manatee forage needs, special recreational events, and even weather patterns.

Integrate all plant management methods
Because the target plants are maintained at a low level, flexibility exists to introduce new and innovative control methods which will further reduce the dependency upon herbicides, methods such as biological control releases.

Let the public know what to expect
The maintenance control program involves local, state and federal agencies in the planning process, including the Department of Environmental Protection, the Florida Fish and Wildlife Conservation Commission, the U.S. Army Corps of Engineers, the U.S. Fish and Wildlife Service, the Water Management Districts, and several county and city governments. These planning meetings are open to the public, and public input is received. This means that citizens know that when management activities occur, those control activities have been reviewed and have been deemed necessary. Information is available as to the overall goal of a program, how a program will benefit the public's use of the waterbody, and in general just what to expect from a program. Building trust, confidence and interaction with the public is a continuing objective of the aquatic plant management program and a primary driver of this web site.

Decades of experience and many years of technical research have taught the Florida Department of Environmental Protection that maintaining noxious aquatic weed species at low levels is the most environmentally sensitive method for managing our serious noxious aquatic weed problems.

We've learned that "maintenance control" management:

Reduces the environmental impact of noxious weed species;

Allows greater use of our waters;

Uses less herbicide;

Greatly reduces the overall costs; and

Promotes public confidence and cooperation.

COMMONLY ASKED QUESTIONS
While on a Florida waterbody, one may encounter a spray crew applying herbicide to invasive, exotic aquatic plants. Some fishermen, boaters, swimmers and others have questioned the need for and safety of weed control programs. Here are a few of the most commonly asked questions and answers regarding Florida's aquatic plant management program.

1. Are aquatic herbicides safe to use?
In their concentrated form, all herbicides should be handled with great care. However, once diluted according to label instructions for application into an aquatic environment, they are considered safe for that use by the U.S. Environmental Protection Agency, the Florida Department of Agriculture and Consumer Services and are permitted by the Florida Department of Environmental Protection. Aquatic herbicides meet the most stringent safety standards under federal and state regulations; none of those permitted for use in water are "restricted-use" herbicides.

2. Does the Florida Department of Environmental Protection or any of its contractors have a chemical quota to fill?
No, only the amount of herbicide needed to adequately control aquatic weeds is allowed for use. The department spends less money for the control of water hyacinth and water lettuce each year due to the success of the department's maintenance control program. Because large floating mats of weeds are not allowed to build-up, less chemicals are used and less muck is deposited on the bottoms of our waterbodies.

3. Why doesn't the department use mechanical harvesters to control floating plants such as water hyacinth and water lettuce?
Research done on Lake Okeechobee and other places throughout the state has consistently shown that harvesters alone are ineffective for large-scale control of these fast-growing exotics. At times when harvesters have replaced chemicals, the plants grew out of control. It is also far more cost-effective to use chemicals in place of mechanical harvesters. One crew applying herbicide can cover approximately 10-15 acres a day, whereas a crew operating a harvester can generally clear only one to two acres a day. In addition, harvesting is not selective, removing native, non-target plants and animals that are in their paths. Repeated use of mechanical harvesters can significantly reduce the numbers of fish and other animals living among invasive plants. Finally, the use of harvesters can accelerate the spread of invasive plants: harvesters fragment invasive plants and these fragments float away and quickly take root in other parts of the water body; and since invasive exotic plants grow back faster than native plants, only the invasive exotics remain after one to two cuttings.

4. Is the muck in the shallow fish spawning areas the result of the aquatic plant management program?
All dying and decaying plants contribute to the muck layer, but the bulk of the muck comes from the natural die-off of living invasive exotic as well as native plants. Water level stabilization for flood control purposes creates conditions that result in too many plants in the shallow areas. This not only reduces fish spawning areas, but also results in large muck deposits. The muck removal projects designed by the Florida Fish and Wildlife Conservation Commission (FWC) help offset this problem.

5. Does the department purposely kill native plant species during invasive exotic plant control operations?
No, although sometimes that appears to be the case. Under the maintenance control program, even small patches of floating weeds are sprayed. Sometimes they are mixed in with native plants which unintentionally get sprayed while trying to control the exotics. Chemical formulations are used which will kill the exotics, but will only temporarily brown the natives. Spray crews are directed to minimize, as much as possible, exposure of native plants to chemicals.

Also, the natural browning of plants due to seasonal change, and damage caused by insects or disease is sometimes confused with the effects of chemicals on aquatic plants. But native plant species are not targeted for control unless they have become noxious.

Damage from insects, shown here on this American lotus leaf, is sometimes mistakenly confused with damage done by chemicals (herbicides)	Native plants, such as this stand of American lotus, are usually not targeted for control unless they become noxious. The damage shown here is the result of insects, not chemicals.	This worm is most likely the culprit for much of the damage you see in these photos.

6. Do the herbicides kill fish or cause them to leave areas that have been sprayed?
The FWC and the University of Florida have done studies on Florida waterbodies which indicate that spraying does not affect the catchability of fish, or adversely affect "bedding" fish. Isolated fish kills do sometimes naturally occur due to low levels of dissolved oxygen in the water. When dead plants begin to decay, and the organisms that break down the plant material use the dissolved oxygen in the water, then it may adversely affect the dissolved oxygen levels. It is to avoid fish kills that the department requires that the dissolved oxygen in the water to be treated be measured beforehand. These activities are also sometimes spread out over a five or six week period to assure no adverse affects on the dissolved oxygen levels.