Fact Sheet FS386
Aquatic vegetation is an essential element of a healthy lake, pond, and reservoir ecosystem. At moderate densities, aquatic plants produce oxygen, serve as a food source for a variety of aquatic, semi-aquatic and upland species, and provide vital habitat as cover for fish and other aquatic organisms. However, when aquatic plants are overabundant, they can create ecological problems that adversely affect water quality and aquatic life as well as interfere with human use of water. Under such conditions it may become necessary to implement some form of control to lessen the density of plants or control the presence of invasive, non-native species.
The use and management objectives for a particular body of water will largely determine the need for management or control of aquatic plants. For example, for waterbodies supporting boating and swimming, the management of aquatic plants may need to be more aggressive to maintain open water areas where such recreational activities can occur with limited conflicts. Conversely, waterbodies promoting angling and waterfowl management will typically be managed to support a denser aquatic plant community to provide more habitat.
As with any type of weed control, aquatic or terrestrial, identification is the first step in developing a sound control program. It is critical to start by properly identifying the plant community and, when possible and practical, quantifying species composition and species distribution. In assessing aquatic weed problems, all traditional methods of control should be evaluated for short- and long-term effectiveness, applicability to the management situation, level of plant control desired, and cost.
Nonchemical Controls
Nonchemical control methods should always be considered before resorting to chemical control. Sometimes adequate weed control can be achieved using non-chemical means. Other times, nonchemical methods are used along with chemical control measures to obtain the best results.
Preventive Control
Preventive control reduces plant growth by manipulating the two major regulatory factors: nutrients and sunlight. Excessive nutrients, particularly phosphorus, produce large increases in the amount of aquatic vegetation and algae. Limiting surface runoff that contains nutrients and practicing other forms of nutrient control are best in the long run. In aquatic habitats, light penetration determines the depth to which submerged (underwater) plants can grow. Deeper water (more than 3 feet) reduces the amount of light reaching submerged plants and thereby reduces photosynthesis and the amount and rate of resulting plant growth. However, it should be noted that many invasive species can successfully grow in low light situations and at depths far in excess of three feet.
Mechanical Control
Mechanical control covers those strategies that physically cut and/or remove vegetation. Think of this as underwater mowing. Although messy, time-consuming and usually more expensive than chemical control, it can be an effective management tool. This is especially true when herbicide use is a concern or when area-selective control is desired. Equipment varies from simple hand rakes to specially designed aquatic weed harvesters. In New Jersey, one or two harvests a year can keep weeds at acceptable levels. Mechanical harvesting may sometimes be used in conjunction with chemical treatments, either before the treatment is conducted, as a supplement to the treatment in hard-to-reach areas, or as a means of removing treated plants as they are decomposing. Please note that hand harvesting and conventional mechanical harvesting are not regulated activities. However, hydroraking (a mechanical control option that removes the entire plant including its roots) does require an NJDEP permit.
Cultural Control
Cultural control includes the use of dyes, bottom barriers, physical manipulation, and aeration techniques. Nontoxic dyes act as light screens and can be used to inhibit some types of submerged plant growth. Many lake colorants are available that turn the water blue, black or blue-black, yet allow visibility into the water for 2 to 3 feet. One product, Aquashade, is EPA-registered for controlling aquatic plant growth. By blocking specific light rays critical to photosynthesis, the dyes reduce plant growth at depths greater than 2 feet. As such, these products may help control benthic and submerged plant growth. In New Jersey, an initial application and a mid-season application are suggested. Dyes should only be used in ponds with little or no flow as flowing water will flush the dye from the pond. Also note that some of these products are regulated by NJDEP and require a permit for their application. It is thus advisable to carefully review the product label. Any dye label claiming plant or algae control, as opposed to simply being a water colorant, likely requires NJDEP authorization prior to its use.
Underwater aerators (bubblers) benefit aquatic systems by increasing the amount of dissolved oxygen into the water and water column mixing (both vertically and horizontally). Although aeration is not highly effective in controlling aquatic weed, it can help control algae growth and can produce a shift in species from noxious cyanobacteria (blue-green algae) to desirable diatoms, chrysophytes, and green algae (See Rutgers FS1216). The added oxygen and water circulation is beneficial to fish.
Physical manipulation involving drastic measures is sometimes useful. The most common method is "drawdown." This is the seasonal draining of a pond or lake to expose littoral zone (near-shore) plants and bottom sediments. Sediment desiccation and/or freezing can help control the growth and distribution of certain plants, including their seeds. The cut-and-flood method effectively controls rooted emergent species by raising the water level 4 to 5 feet after the weeds are cut. Drawdown must be approved and require a permit from the NJDEP Bureau of Freshwater Fisheries. Also, note that certain invasive species (including curly leaf pondweed and Hydrilla) can actually benefit from drawdown. It is therefore important before considering this weed control option to know the types of plants present in the lake or pond.
Biological Control
Biological control of aquatic vegetation may be possible using triploid (sterile) carp. However, it may take up to 3 years to reduce the aquatic weed levels to an observable level, and they may avoid the targeted weed altogether. The introduction of this fish into the waters of New Jersey requires a Permit from the New Jersey Division of Fish and Wildlife. For more information call 908-236-2118 or write to: New Jersey Division of Fish and Wildlife, Lebanon Fisheries Lab, P.O. Box 134, Lebanon NJ 08833.
Chemical Control
In New Jersey, before applying any aquatic pesticide, review "N.J.A.C. 7:30-9.3", the regulation that mandates an Aquatic Pesticide Permit for most applications of pesticides to any "waters of the State" or on "Aquatic sites". In most cases, the application needs to be conducted by a NJDEP Category V licensed applicator and subject to the limitations set forth by the NJDEP in the treatment permit. For more information visit the NJDEP Bureau of Compliance and Enforcement, Aquatic Pesticide Permit Application and Instructions site.
When choosing an herbicide, consider these essential factors. The weed or weeds must be properly identified, and most aquatic herbicides control only certain plant/algal types, as indicated on the pesticide label. Listed in Table 1 are the commonly occurring aquatic weeds of New Jersey and the herbicides labeled used for their control.
Consider the uses of the water to be treated. Most aquatic herbicides restrict use of the water until the herbicide has been degraded, inactivated, or dissipated. Table 2 lists aquatic herbicides and their post-treatment water-use restrictions. Check the pesticide label for limitations and length of restricted use; they may be major considerations. This is especially true for water used for irrigation or consumption.
The timing of the treatment is also important when determining which herbicide to use. There are no pre-emergent aquatic herbicides. This means that before they are applied there needs to be a fair amount of plant growth. Most aquatic herbicides should be applied in mid- to late spring or early summer, after vigorous growth has begun, but before weeds have reached the surface and have started to form floating mats or set seed. Waiting too late in the season will result in difficulties in applying the herbicide, poor dispersion of the herbicide through the water, and increased danger of fish kill due to lack of oxygen from large masses of decaying vegetation. For algae control, it is particularly important to treat early, as soon as the algae becomes visible. Delaying treatments until a dense mat has covered the surface may result in poor control or once gain a fish kill due to the lack of oxygen resulting from the decomposition of high densities of decaying algae.
It should be noted that temperature affects the efficacy of some herbicides. Herbicides are not effective on aquatic weeds when the water is too cold. This is especially true of the systemic herbicides that must be absorbed and assimilated by the plant. Thus, the water temperature should be in the upper 60s (°F), usually from late April to early June. Also as previously noted, do not wait for the plants to reach high densities before treating; that is, apply herbicides as soon as the plants are actively growing, and water temperatures are compatible. In all cases, closely follow the product's label regarding treatment dose and application recommendations, and any permit limitations set forth by NJDEP.
The method of application may affect your choice if a certain type of equipment is needed for treatment to be effective. Consult labels for specific instructions on how to treat the area. For small ponds, it may be possible to conduct successful treatment using a backpack sprayer. For larger ponds and lakes, the treatment may require the use of boat-based application equipment.
Also, consider the probability of retreating (even within the same year), an herbicide's toxicity to fish, the potential for damage to shoreline vegetation, and the cost of the herbicide for a specific management program.
Finally, there are public notification requirements associated with the majority of herbicide treatments. This includes pre-treatment notifications and post-treatment posting of the treated water. More information on public notices is available via the NJDEP Pesticide Control Program website.
Herbicides Labeled for Use in Aquatic Areas
Only a handful of herbicides are labeled for use in aquatic ecosystems. The label must specifically state that the herbicide is intended for aquatic use. Applying unlabeled products violates state and federal regulations.
Chemicals labeled for use in aquatic areas are described in the following paragraphs. Consult product labels for use rates. Rates for all products vary according to product formulation, species present, and stage of plant growth. Follow label directions carefully in calculating dosage, and do not overdo it. Most aquatic herbicide labels provide recommended dosages on the basis of acre-feet (volume measurement). Acre-feet measurements are calculated by multiplying the surface area by the average depth. For example, a pond with a surface area of ½ acre and an average depth of 4 feet contains 2 acre-feet (4 times ½ acre). The herbicide label tells you the amount to apply per acre-foot. Again, NJDEP may further limit the application dose as part of the treatment permit.
Copper Sulfate
Copper sulfate (many trade names available) is used strictly for the control of algae. It has little or no effect on flowering plants at normal use rates. The copper is formulated as copper sulfate pentahydrate (CSP). No restrictions apply on the use of the water following treatment. Copper sulfate is a contact herbicide; therefore, algae must be exposed directly to the compound. It is essential to distribute copper sulfate well in the water where the plants are growing. Vegetation dies 3 to 5 days following treatment. Several treatments may be needed each season to maintain the desired level of control. The granular form is best applied by putting it in a burlap sack and towing it by boat around the pond until it dissolves. The powder form is best used by dissolving it in water and spraying it onto the algae mats and into the water. Caution: Do not use copper sulfate in water inhabited by trout. Copper sulfate must be used carefully in waters inhabited by grass carp, common carp, and goldfish.
Copper Chelates
Copper chelates (many trade names available) are formulations that chemically bind copper in an organic molecule to delay the copper from precipitating from the water. Think of these products as "slow-release, time-delayed" copper treatments available not only in liquids formulations but also granules, and powders. Although more expensive on a unit basis than standard copper sulfate, the chelated products offer somewhat longer-lasting treatment times. The slower release also makes these projects slightly less toxic to sensitive fish (except trout) than standard copper sulfate. Like copper sulfate, most copper chelates are contact products, meaning their effectiveness in direct contact with plants. As with standard copper sulfate, these products have no water-use restrictions (other than toxicity to trout), making them ideal for weed control in irrigation ponds.
Endothall
Endothall (Hydrothol, Aquathol) is a contact herbicide that requires reasonably good distribution to be effective. Restrictions on the use of treated water range from waiting 3 days before consuming fish to waiting 7 to 25 days for irrigation. Endothall is available in two salt forms: amine salt (Hydrothol) and dipotassium salt (Aquathol). Hydrothol liquid should only be applied by licensed applicators, as even at low doses it can cause fish kills and severe skin burns. Aquathol also should be used with caution, but has less environmental, fish-life and applicator safety issues than Hydrothol. Spray or inject the liquid-water mix into infested areas or use as spot treatments. Aquathol is especially effective when trying to control plant growth in more turbid waters.
Diquat-dibromide
Diquat-dibromide (Reward, Weedtrine-D) is a contact herbicide. Do not apply to flowing water and ponds should have little overflow. Optimal effectiveness depends on direct contact with the plant, either by dispersing the herbicide completely in the water or by spraying it directly on the plant. Spray is used for duckweed control. Restrictions on the use of treated water range from 1 to 5 days, depending on the activity. Do not use diquat in muddy water or on silt-covered plants because the chemical becomes deactivated, resulting in poor control. Diquat is often used as a tank mix with the liquid forms of copper chelates and the dipotassium salt of Endothall to provide a broad-spectrum control for aquatic weeds. However, before conducting any tank mix with other products, consult with NJDEP.
2,4-D
2,4-D (Aqua-Kleen, Navigate, Barrage, and others) provides selective control of various emergent and floating plants as well as certain submerged species. This is a systemic herbicide that must be absorbed and assimilated by the plant to achieve control. The granular ester formulation is used for spot treatments and to control low-growing, submerged plants. The herbicide should not be used in water intended for irrigation, domestic use, or watering livestock. Fish toxicity varies according to the formulation. Also, because 2,4-D affects terrestrial broadleaf plants, care needs to be taken to avoid the unintentional application of the product on upland plants located adjacent to the targeted aquatic plants. This can be a problem with using 2,4-D to control emergent aquatic and semi-aquatic plants.
Fluridone
Fluridone (Sonar) is a broad-spectrum herbicide that controls or reduces the activity of a wide variety of submerged, emergent, and floating plants and shore-line grasses. It does not control algae. This is a systemic herbicide, meaning that to be effective it needs to be assimilated by the plant. Its mode of control is through the alteration of the plant's ability to successfully photosynthesize. Die-off tends to be far slower than that experienced with the contact herbicides that actually damage and break down the plant's cell wall. When properly applied and timed, a single Fluridone treatment may provide control for a year or more. For best results, it should be applied during early stages of rapid weed growth. Symptoms are visible in 7 to 10 days, but 30 to 90 days are needed for complete weed removal. Fluridone is not recommended for spot treatments or in areas where dilution or water movement does not allow sufficient contact time. Irrigation is restricted from 7 to 30 days after application. Fluridone should not be applied within ¼ mile of a potable water intake. It should not be applied in water or near a shoreline where the roots of desirable trees and shrubs extend, as injury to those trees and shrubs might occur.
Glyphosate
Glyphosate is another systemic herbicide that controls the plant from the point of foliage contact into the root system. While it is an effective means of controlling floating plants (e.g., water lily, duck weed and water meal), it is not recommended for controlling plants that are completely submerged or have most of their foliage underwater. Uptake occurs within 6 hours after treatment, with wilting and yellowing of plants occurring 2 to 7 days after treatment. The best time to treat is when plants are mature or as specifically recommended on the label. Glyphosate should not be used within ¼ to ½ mile of a potable water intake. Because many of the floating plants have a waxy surface, a surfactant is often used in conjunction with glyphosate when treating floating plants and emergent plants (e.g., cattail and Phragmites). The surfactant helps the product adhere to the plant's leaves and stem, resulting in better control and product efficacy.
Final Notes
When developing a weed control program, always consider the possible environmental effects associated with the control measure. Always follow label recommendations and NJDEP permit limitations. It is highly advisable (and often required by NJDEP) in advance of conducting an herbicide treatment to measure the waterbody's temperature, pH, dissolved oxygen level, and hardness. Not only can these parameters affect the effectiveness of the product, but they can trigger undesirable secondary environmental impacts. As repeatedly noted, avoid the chemical treatment of heavy infestations, especially in the summer, as the rapid decomposition of the dead plant mass may lead to oxygen depletion and fish kill. It is also advisable to conduct partial treatments at 2- to 3-week intervals during these times. In addition to herbicides, possible sources of toxicity in aquatic weed control include adjuvants, surfactants, and wetting agents. Thus, if using any such products in conjunction with an herbicide, follow the manufacturer's guidance and/or limitations set forth by NJDEP.
Many of the pesticides used in aquatic weed control programs have restrictions on the use of the treated water for potable purposes and/or other uses such as swimming, irrigation, crop spraying, or stock watering. The use of the treated water is dictated by the product label. Table 2 is the New Jersey Pesticide Control Program's interpretations of the various water use restrictions found on the aquatic pesticide labels. These guidelines are to be used as a supplement to the pesticide label. These guidelines do not supersede imposed Aquatic Pesticide Permit conditions or the pesticide label directions. Nor do they release the applicator from the responsibility of making sure that all users of the treated water are aware of the water use restrictions.
| Aquatic Weed | Herbicide Products | |||||||
|---|---|---|---|---|---|---|---|---|
| Common Name | Scientific Name | 2,4-D | Aqua- thol |
Copper sulphate | Diquat | Gly- phosate |
Hydro- thol |
Fluridone |
| Algae | ||||||||
| Filamentous algae | Many | NL | NL | L | L | NL | L | NL |
| Microscopic algae | Many | NL | NL | L | NL | NL | NL | NL |
| Stalked algae | Chara and Nitella | NL | NL | L | NL | NL | L | NL |
| Flowering Plants | ||||||||
| Submerged | ||||||||
| American elodea | Elodea canadensis | NL | NL | NL | L | NL | L | L |
| Bladderwort | Utricularia spp. | C | NL | NL | L | NL | NL | L |
| Brittle naiad | Najas minor | NL | L | NL | L | NL | L | L |
| Buttercup | Ranunculus spp. | C | NL | NL | NL | L | NL | NL |
| Fanwort | Cabomba caroliniana | NL | NL | NL | NL | NL | NL | L |
| Clasping-leaf pondweed | Potamogeton perfoliatus | NL | NL | NL | L | NL | L | L |
| Coontail | Ceratophyllum demersum | C | L | NL | L | NL | L | L |
| Curly-leaf pondweed | Potamogeton crispus | NL | L | NL | L | NL | L | L |
| Eel grass | Vallisneria americana | NL | NL | NL | NL | NL | L | NL |
| Flat-stemmed pondweed | Potamogeton zosteriformis | NL | L | NL | L | NL | L | L |
| Horned pondweed | Zannichellia palustris | NL | L | NL | NL | NL | L | NL |
| Leafy pondweed | Potamogeton foliosus | NL | NL | NL | L | NL | L | L |
| Sago pondweed | Stuckenia pectinatus | NL | L | NL | L | NL | L | L |
| Small pondweed | Potamogeton pusillus | NL | L | NL | L | NL | L | L |
| Southern naiad | Najas guadalupensis | NL | L | NL | L | NL | L | L |
| Water milfoil | Myriophyllum spp. | C | L | NL | L | NL | L | L |
| Waterstargrass | Heteranthera dubia | C | L | NL | NL | NL | NL | NL |
| Hydrilla | Hydrilla verticillata | C | L | NL | L | NL | C | NL |
| Free-floating | ||||||||
| Common duckweed | Lemnaminor | L | NL | NL | L | NL | NL | L |
| Star duckweed | Lemna trisulca | L | NL | NL | L | NL | NL | NL |
| Water pennywort | Hydrocotyle spp. | C | NL | NL | L | L | NL | NL |
| Watermeal | Wolffia spp. | NL | NL | NL | NL | NL | NL | L |
| Rooted floating | ||||||||
| American lotus | Nelumbo lutea | C | NL | NL | NL | C | NL | C |
| American pondweed | Potamogeton nodosus | NL | L | NL | L | NL | L | L |
| Floating pondweed | Potamogeton natans | NL | L | NL | L | NL | L | L |
| Illinois pondweed | Potamogeton illinoensis | NL | NL | NL | L | NL | C | NL |
| Largeleaf pondweed | Potamogeton amplifolius | NL | L | NL | L | NL | L | L |
| Spatterdock | Nuphar advena | C | NL | NL | NL | L | NL | C |
| Water lily | Nymphaea spp. | C | NL | NL | NL | L | NL | C |
| Waterpurslane | Ludwigia palustris | NL | NL | NL | NL | NL | NL | C |
| Watershield | Brasenia schreberi | C | NL | NL | NL | NL | NL | C |
| Waterthread pondweed | Potamogeton diversifolius | NL | L | NL | L | NL | L | L |
| Emergent | ||||||||
| Arrowhead | Sagittartria spp. | C | NL | NL | NL | NL | NL | NL |
| Bulrush | Scirpus spp. | C | NL | NL | NL | L | NL | NL |
| Bur reed | Sparganium spp. | C | L | NL | NL | NL | NL | NL |
| Cattail | Typha spp. | C | NL | NL | L | L | NL | C |
| Creeping water primrose | Jussiaea repens | C | NL | NL | NL | L | NL | C |
| Pickerelweed | Pontederia spp. | C | NL | NL | NL | NL | NL | NL |
| Purple loosestrife | Lythrum salicaria | NL | NL | NL | NL | L | NL | NL |
| Sprikerush | Eleocharis spp. | NL | NL | NL | NL | NL | NL | C |
| Water smartweed | Polygonum spp. | C | NL | NL | NL | L | NL | C |
| Willow | Salix spp. | C | NL | NL | NL | L | NL | NL |
| NL= not labeled for control of this species; L= labeled for control of this species; C= check labels for specific species listed (each 2,4-D and Sonar product is different). | ||||||||
| Source: Information has been collected from chemical manufacturers’ labels. Although some products could control more species, only the species listed on the label are included. | ||||||||
This guidance chart below of aquatic pesticide active ingredients does not supersede any registered aquatic pesticide product label directions unless the guidance statement is more restrictive.
| Pesticide | Water Use and Treatment Restrictionsh | Well* <10 feet from shore |
Well* >10 feet from shore |
|---|---|---|---|
| Aquashade | Outflow from aquatic site must be little to none. Do not apply to flowing water. Aquatic site must be under the total control of the user. Do not use in aquatic sites where water is used for potable water. | Water use restrictions same as if a surface water intake. | No restrictions |
| Bispyribac-sodium | Do not retreat within 14 days. Do not use treated water to irrigate food or ornamental crops until the concentration of in water is less than or equal to 1 ppb. Treated water may not be used as a water source for livestock until the concentration in water is less than or equal to1 ppb. | Water use restrictions same as if a surface water intake. | No restrictions |
| Calcium Hypochlorite | Do not apply to any aquatic site not under the total control of the user. This means that all surface water discharge from the pond can be stopped, by some mechanism, if necessary. No fishing with only limited boating in aquatic site. | Water use restrictions same as if a surface water intake. | No restrictions |
| Carfentrazone-ethyl | Only treat 1/3 to 1/2 of the aquatic site at one time and do not retreat within 14 days. Do not apply directly to water within ¼ mile of an active potable water intake. To make aquatic applications around and within ¼ mile of active potable water intakes, the water must be turned off prior to and for a minimum period of 24 hours after the application. Do not use treated water for irrigation in commercial nurseries or greenhouses. The water use restrictions, depending on dosage rate used, are, 14 days for irrigation of food crops, ornamentals, and turf. | Water use restrictions same as if a surface water intake. | No restrictions |
| Copper/ Copper Sulfate | Treated water must not exceed 1 ppm metallic copper residual if used for potable water. Depending on specific product used, may treat only 1/3 to 1/2 of the aquatic site at one time and do not retreat within 14 days. | Water use restrictions same as if a surface water intake. | No restrictions |
| Diquat | Do not apply to flowing water. Do not apply to any aquatic site not under the total control of the user. Outflow must be little to none or do not treat within 1,000 feet of that outlet. The water use restrictions, depending on dosage rate used, are 1 to 3 days for drinking, 1 day for livestock watering, 5 days for irrigation or spraying of food crops, and 1 to 3 days for irrigation or spraying of ornamentals or turf. The water may be used prior to the above time limits if the concentration of diquat dibromide (calculated as the cation) in the treated water is < 0.02 ppm. If the treatment area is more than 1000 feet from the water use area or intake, the water use restrictions may be waived. Only treat 1/3 to ½ of aquatic site at one time. Do not retreat within 14 days. | Water use restrictions same as if a surface water intake. | No restrictions |
| Endothall | The drinking water setback distance from functioning potable water intakes in the treated water body must be greater than or equal to 600 feet. Do not use fish for feed or food within 3 days of treatment. Do not retreat within 14 days. For Aquathol K & Aquathol Super K, do not use water for irrigation, agricultural sprays, or domestic purposes for 7 days after treatment. For Aquathol K & Hydrothol, do not use water for irrigation, ag sprays, livestock watering or domestic purposes for 7 to 25 days after treatment, depending on the dosage rate used. If the treatment area is more than 1000 feet from the water use area or intake, the water use restrictions may be waived. For Aqua Strike, the water use restrictions, depending on dosage rate used, is 1 to 3 days for drinking, 1 day for livestock watering, 5 days for irrigation or spraying of food crops, and 1 to 3 days for irrigation or spraying of ornamentals or turf. |
Water use restrictions same as if a surface water intake. | No restrictions |
| Florpyrauxifen-benzyl | Do not retreat within 14 days. Turf may be irrigated immediately after treatment. The water use restrictions, depending on dosage rate used, is 3 to 35 days for landscape vegetation and other forms of non-agricultural irrigation. | Water use restrictions same as if a surface water intake | No restrictions |
| Flumioxazin | Do not retreat within 28 days. For Schooner 51% WDG and Semera 51% WDG, the water use restrictions, depending on dosage rate used, are 3-12 days for irrigation of ornamentals and turf and 5 days for irrigation of food crops, ornamentals grown for production in greenhouse and nursery. For Depth Charge, do not apply directly to water within 600 ft of a potable water intake. * (Refer to 2,4-D restrictions listed in the chart below). | Water use restrictions same as if a surface water intake. | No restrictions |
| Fluridone | Keep ¼ mile from potable water intake unless dosage rate used is <0.02 ppm. Do not exceed the maximum labeled dosage rate for a given treatment site per season. Do not retreat within 7 days. Depending on the type of aquatic site treated and the formulation used, the water use restrictions are as follows: no irrigation of established trees for 7 days, 14 to 30 days for irrigation of row crops, turf, or ornamentals (Specified on product label). | Water use restrictions same as if a surface water intake. | No restrictions |
| Glyphosate | Keep ½ mile from potable water intake unless water intake can be shut off for at least 48 hours. The water intake can be used again prior to 48 hours only if the concentration of glyphosate in the treated water is <0.7 ppm. Do not retreat within 14 days. | Water use restrictions same as if a surface water intake. | No restrictions |
| 2,4-D | Do not apply to aquatic sites where water is used for irrigation, agriculture spraying, livestock watering, or domestic purposes. Do not retreat within 21 days. Do not swim in treated water for a minimum of 24 hours after application. Do not exceed 70 ppb for potable water consumption. | Water use restrictions same as if a surface water intake. | No restrictions |
| Hydrogen Peroxide |
Only treat 1/3 to ½ of aquatic site at one time. Do not retreat within 4 days. Do not apply directly to potable water intended for human consumption. | Water use restrictions same as if a surface water intake. | No restrictions |
| Imazapyr | Only treat 1/3 to ½ of aquatic site at one time. Do not retreat within 10 days. Do not use treated water to irrigate greenhouses, nurseries or hydroponics etc. until concentration is less than or equal to 1ppb. For Arsenal, Habitat, and Nufarm Polaris, do not apply directly to water within ½ mile of an active potable water intake. To make applications within ½ mile of active potable water intakes, the water intake must be turned off during application and for 48 hours after the application. For Clearcast, applications made within ¼ mile of an active potable water source cannot exceed 500 ppb, but water concentrations resulting from injection and/or foliar applications may not exceed 50ppb. | Water use restrictions same as if a surface water intake. | No restrictions |
| Penoxsulam | Do not retreat within 7 days. Do not use treated water for irrigating greenhouse or nursery plants. There is no restriction on use of treated water for turf irrigation if concentrations are less than 30ppb. Other restrictions are dependent on concentration and targeted use. Refer to product label. | Water use restrictions same as if a surface water intake. | No restrictions |
| Sodium Carbonate | Only treat 1/3 to ½ of aquatic site at one time. Do not retreat within 4 days. | Water use restrictions same as if a surface water intake. | No restrictions |
| Sodium Hypochrorite | Do not apply to any aquatic site not under the total control of the user. This means that all surface water discharge from the pond can be stopped, by some mechanism, if necessary. No fishing with only limited boating in aquatic site. | Water use restrictions same as if a surface water intake. | No restrictions |
| Triclopyr | Treated water may not be used for irrigation purposes for 120 days or residue levels are less than or equal to 1 ppb. The setback distance for applications to potable water intake, depending on dosage rate used and concentration are within 200ft. to 2600ft. | Water use restrictions same as if a surface water intake. | No restrictions |
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June 2025
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