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Boat, Gear and Equipment Decontamination and Disinfection Manual Code 9183.1

Best Management Practices

The general public is required to follow the decontamination steps identified in s. NR 40.02(44) and NR 40.07 to prevent the spread of invasive species. This webpage outlines best management practices (BMPs) for the boat, gear and equipment. Decontamination and disinfection manual code, which requires all Wisconsin Department of Natural Resources employees, agents, and permittees that transport equipment between waters to take additional prevention steps. If you are unsure if you are required to follow this guidance, please review the Common Questions and Answers. If you still have questions, contact the person that issued your contract or permit or the DNR invasive species team.

  1. Manual Code #9183.1
  2. Full BMPs for boat, gear and equipment decontamination
  3. Check for species present in the work area using one of the following tools:
  4. Select the best disinfection method for species present

General practices

  • Be aware of infestations in your management area. The “Where to find aquatic invasive species” document has been created to assist in finding where species have been documented and verified across the state.
  • If a high percentage of work is done in waters with invasive species, consider dedicating certain gear to be used only in those waters.
  • If possible, work with local volunteers and use their boats to collect samples. If the volunteer’s boat is staying on the water body, then the department’s equipment will be the only items that need to be disinfected.
  • When working on multiple water bodies, arrange sampling plans to progress from the least to the most likely to be contaminated areas when working within the same water body. When working on different reaches of the same stream, decontaminate whenever equipment crosses a barrier while going upstream.
  • Consider a purchase of wading gear and boots with the fewest places for organisms and debris to become attached (i.e. one-piece systems with full rubber material and open cleat soles).
  • Keep an eye out for any invasive species that may not have been previously recorded but may get on your gear if present. Adjust decontamination plans and follow Wisconsin’s Rapid Response Framework when new occurrences are observed.
  • Reduce the number of plants, sediment or organisms that are removed from the water into boats or sampling gear.
  • Regularly inspect and clean gear while working.
  • Fully inspect equipment and remove any organisms present.
  • Scrub equipment with a stiff-bristled brush and/or wash with soapy water. This simple step will aid in the removal of small organisms and seeds, as well as remove organic materials that make disinfection less effective. Scrubbing could damage the anti-fouling paint/coating of some boat hulls so check manufacturers’ recommendations.
  • Only use pressure washing if it’s used in conjunction with hot water or on the site where work took place. Otherwise, it can aid in the spread of AIS since it removes organisms, but may not kill them.
  • When scrubbing fabric, be careful to brush with the nap (direction of fabric), as brushing against the nap could cause small seeds to become more embedded. Scrubbing should be followed by a rinse with clean water.

Gear-specific methods

Personal gear
  • To remove debris, scrub personal gear with a stiff-bristle brush and rinse with clean water (municipal, bottled, well, etc.), and then refer to one of the disinfection options outlined in the manual code.
  • An adhesive roller can be used on clothing to remove seeds and plant materials that could spread.
  • Note that hot water and steam can damage technical fabrics (e.g. Goretex) and melt seams of waders/boots.
  • Heat-resistant gloves, nitrile gloves, splash goggles, face shields, emergency eyewash stations, and other personal protective equipment should be used.
  • When using chlorine or Virkon® Aquatic solution on personal equipment, some individuals spray and place equipment in plastic bags to maintain a wet surface for the desired contact time, however, soaking is more effective with certain species/disinfectant combinations, and bagging sprayed equipment does not increase the efficacy of spray applications.
Sampling gear
  • There are several options for disinfecting smaller gear while in the field, but the first step is to always remove any organic material from the sampling gear. Scrubbing gear with a stiff-bristled brush is helpful.
  • Electronic sampling gear may be damaged by the disinfection methods listed in the manual code and should only be rinsed with clean water (municipal, bottled, well, etc.). See the manufacturer’s instructions for further directions on the cleaning of sensitive gear.
  • For other gear used in water choose one of the following options after scrubbing and rinsing:
    • Use steam, hot water, chlorine solution, or Virkon® Aquatic solution to disinfect equipment.
    • If using Chlorine or Virkon® Aquatic solution, fill a tub with a disinfection solution and place all equipment in the tub for the appropriate contact time. While soaking is preferred, it is also possible to spray gear with a disinfection solution so a wet surface is maintained for the appropriate contact time; however, this method is not as effective as soaking.
    • The gear should be rinsed with clean water (i.e. municipal, bottled, well, etc.) after applying disinfection to maintain the integrity of the equipment.
    • Use a completely new set of gear for each waterbody during the workday and disinfect all gear at the end of the day.
  • Organic debris must be removed before disinfection. The most effective way to remove organic debris from nets is via a method of rinsing. Power washing is not required, but nets could be sprayed with a garden hose to remove debris.
  • Nets may be steam cleaned, washed and dried thoroughly for five days, or washed and treated with a disinfection solution. Nets should be placed in the disinfection solution for the appropriate contact time for the solution being used. After rinsing, the nets can be used immediately or hung to dry.
  • Remove organic material from boats, trailers, and live wells.
  • Drain water from live wells, bilges and pumps.
  • Scrub all exterior surfaces with a long-handled stiff-bristled brush to remove sediments. Scrubbing could damage the anti-fouling paint/coating of some boat hulls so check the manufacturer's recommendations.
  • The outside and inside of the boat, trailer, live wells, bilges and pumps should be steam cleaned or sprayed with the disinfection solution and left wet for the appropriate contact time.
  • The inside of the live wells, bilges and pumps should be in contact with disinfection solution at the appropriate time as well.
  • Due to the difficulty of ensuring appropriate contact times, steam cleaning is the preferred method for decontamination when possible.
  • Run pumps so they take in the disinfection solution and make sure that the solution comes in contact with all parts of the pump and hose.
  • The boat, trailer, bilges, live well and pumps should be rinsed with clean water after the appropriate contact time.
  • Every effort should be made to keep the disinfection solution and rinse water out of surface waters. Pull the boat and trailer off the ramp and onto a level area where infiltration can occur and away from street drains to minimize potential runoff into surface waters.
  • After removing from the water, scrub sediments off the exterior of the motor and then tip the motor down and allow water to drain from the engine.
  • Alternatively, and especially for motors moored in water for several days or more, submerge the lower unit in a container of disinfectant and tun the motor to ensure contact with all internal parts and allow for the appropriate contact time.
  • Or rig up a bucket with a thru-hull fitting on the bottom and attach that fitting to a short (6-foot) piece of garden hose to lower unit muffs.
    • Install a small valve between the hose and the muffs to control the flow of disinfectant. The pail of the disinfectant can then be set in the back of the boat and gravity fed into the lower unit.
    • Next, start the engine and run it just long enough to see the solution to run out the exhaust and the tell-tale.
    • Never run the engine without disinfectant or freshwater flowing into the lower unit.
    • Allow the solution to remain in the motor for the appropriate contact time.
    • A non-corrosive (Virkon® Aquatic) is recommended for use to protect the impeller.
  • Rinse external surfaces with clean water after disinfection.
  • Flush the motor with fresh water for 2 minutes following the instructions outlined in the owner’s manual.
Heavy equipment
  • Scrub equipment with a stiff-bristled brush or spray with pressurized water to remove any sediment.
  • Steam-cleaning or hot water (≥140° F) is an effective method for disinfecting heavy equipment.
  • Steam-cleaning will not be effective if soil and other organic matter are present so be sure to scrub equipment with a stiff-bristled brush.
  • Decontamination should take place in areas where equipment is unloaded and loaded.
  • Before transporting a piece of heavy equipment from one project site to the next, debris and soil must be cleaned off the tracks, tires and other portions of equipment by hand with hand tools or with pressurized water.

Method-specific information

  • Steam is effective in killing a wide range of organisms and fish pathogens.
  • Steam cleaners can work well in small spaces and on items such as small boat hulls, clothing, and heavy equipment. To be the most effective, all sides of the equipment being treated should be sprayed, as well as the inside of the equipment.
  • When setting something on the ground to steam clean, make sure to steam the ground before setting the equipment down.
  • Be careful when steaming over items held together with adhesives, since high temperatures can melt bonds. Inflatable PFDs can also be melted by the use of steam.
  • Use quick strokes with a steam cleaner instead of lingering in one place to decrease the likelihood of causing damage to equipment.
  • When using a low-pressure steam cleaner, steam clean in an enclosed area to ensure proper contact with equipment.
  • Orange cones should be used to mark off areas where steaming is taking place.
  • Use clean water (i.e. municipal, bottled, well, etc.) when steam cleaning to prevent clogging of steam cleaners. Scale build-up on coils within steamers can cause internal pressure to increase, thereby decreasing the efficiency of the unit. It is possible to add a pressure gage to larger steamer units. When unit pressures begin to increase, run a descaler through the unit to get rid of buildup. Softened water can also be used to decrease the likelihood of scale buildup.
  • When you have an option of nozzle types, make sure you pick one that is suited to the surface being steamed and that will ensure the most contact time.
  • All employees who handle steam cleaners shall wear heat-resistant gloves. Depending on the type of steamer used, additional heat-resistant personal protective equipment (PPE) may be required as well. Refer to the equipment’s operation manual for suggested PPE. Be aware that scalding can occur if PPE is not used.
Hot water
  • Hot water works by physically removing AIS and killing some AIS. While some species are killed at lower temperatures, the manual code requires hot water to be at least 140 º F to kill most species.
  • The suggested contact time to kill the most species is 10 minutes.
  • This method becomes more effective when applied with high pressure.
  • It is important to note, most self-serve car washes do not get hot enough to meet the manual code’s temperature requirement.
  • To verify that the hot water spray is effectively heating the contact area, a non-contact infrared thermometer can be purchased at home supply stores for around $30. The distance of reading depends on the product purchased. Be sure to read the product label.
  • Wear heat-resistant gloves when cleaning equipment with hot water.
  • If a boat wash is being used near-surface water, no permit is required for discharges incidental to the normal operations of recreational vessels under the Clean Boating Act (CBA) of 2008. The DNR wastewater program has concluded that “discharges incidental to the normal operations” include discharges from boat washing stations for invasive species. The CBA directed EPA to evaluate recreational vessel discharges, develop management practices for appropriate discharges, and promulgate performance standards for those management practices. It then directs the U.S. Coast Guard (USCG) to promulgate regulations for the use of the management practices developed by EPA and requires recreational boater compliance with such practices. To date, EPA has not developed management practices for appropriate discharges and promulgated performance standards for those management practices. Additionally, the wastewater program has not developed management practices either for discharges incidental to the normal operations of recreational vessels.
  • Make sure equipment and gear are completely dried during the drying period. Surfaces may appear dry while the interior is still wet. Waders, boots, wetsuits, fabric and wood may be difficult to dry thoroughly.
  • If using shared equipment, it is recommended to keep a log of when things are used to ensure the minimum drying period has been met. If there is any possibility of another individual using the shared equipment before the five-day drying period is reached, it is safer to disinfect via other means.
  • Chlorine solution in the form of household bleach (5.25% sodium hypochlorite) can be purchased from a grocery or convenience store. Granular chlorine (70% calcium hypochlorite) can be purchased from a pool supply company.
  • A chlorine solution of 500ppm (1.22 fl. oz. or 2.44 Tablespoon of 5.25% sodium hypochlorite solution of household bleach per gallon water) is effective at killing many AIS and fish diseases; however, it is not effective on spiny water flea-resting eggs, New Zealand mud snails, or Asian clam. For this reason, it is recommended to follow chlorine solution treatments with an additional disinfection method.
  • Because different brands of bleach vary on the amount of sodium hypochlorite used, different amounts of bleach will need to be used to create a disinfection solution of 500 ppm (see Table 1).

    Table 1 Converting household bleach to 500 parts per million of chlorine solution.
    Sodium hypochlorite concentration (%) Ounces chlorine solution per gallon of water Tbsp. chlorine solution per gallon of water
    5.0 1.28 2.56
    5.25 1.22 2.44
    8.25 0.78 1.55
  • Chlorine solutions will begin to lose disinfecting properties after 24hrs, and the more diluted the chlorine solution, the quicker it will deteriorate. Based on this information, it is important to use 0.5% bleach solutions that are less than 24 hours old.
  • Chlorine solutions also deteriorate with exposure to light and heat and in contact with air, metals, metallic ions and organic materials.
  • There are no differences in disinfection abilities between solutions using tap water versus sterile water to mix the diluted chlorine solution, and the cleaning and disinfection abilities of diluted chlorine solutions are not impacted by the temperature of the water used.
  • After opening the original bottle of bleach, it may only be used for a maximum of two months. Write the date the container was opened on the original container. Bleach is best stored out of heat and sun.
  • The words “Bleach Solution” and the date and time of dilution must be written on the container holding the diluted bleach.
  • If stored at a temperature between 50 and 70º F, household bleach retains its disinfection properties for about six months, after which, it degrades into salt and water at a rate of 20% each year. If bleach is stored in locations with higher temperatures, such as a garage or the back of a truck, it will lose its disinfection properties at a quicker pace. Therefore, new bleach should be purchased for purposes of decontamination at the beginning of each field season. If using bleach year-round for decontamination, new bleach should be purchased every 6 months.
  • Chlorine solutions may have corrosive effects on certain articles of equipment, however, these effects can be reduced by rinsing equipment with clean water after disinfection is complete.
  • When using a large quantity of chlorine solution to disinfect equipment, any excess solution must be inactivated with sodium thiosulfate before disposal. Enough sodium thiosulfate should be added to create an 800 ppm solution (3 grams per gallon of water) to neutralize the chlorine solution. Equipment that was treated with chlorine solution does not need to be sprayed with a sodium thiosulfate solution. Sodium thiosulfate is available through pool and chemical supply companies.
  • While bleach is effective in killing most invasive species, it will not dissolve the shells of zebra/quagga veligers. Therefore, it is imperative to use 100% vinegar to dissolve the shells from sampling nets and gear that are used for zebra/quagga mussel sampling. This will also help avoid false positive results in the next sampling event. Bleach will not kill New Zealand mud snails (Hosea and Finlayson, 2005).
  • Caution should be taken to not mix chlorine bleach with other chemicals (e.g., vinegar). After using bleach, rinse well with water and then apply other chemicals that can be applied. Sodium thiosulfate should not be mixed with sodium nitrite, mercury, or iodine.
  • Dispose of unused chlorine in the sanitary sewer and flush with water.
Virkon® Aquatic
  • Virkon® Aquatic is a powder disinfectant in the peroxygen (hydrogen peroxide) family that is 99.9% biodegradable and breaks down to water and oxygen.
  • Virkon® Aquatic should not be used on items made of wood. Since solution soaks into the wood, wood may carry residues that could be harmful to fish.
  • Labeling for Virkon® Aquatic says it is not corrosive at the recommended dilution, however, solutions have been shown to cause degradation to gear and equipment when used repeatedly.
  • Negative impacts of Virkon can be reduced by rinsing equipment with clean water (municipal, bottled, well, etc.) after disinfection is complete. Rinsing might not remove residual Virkon from equipment; therefore, Virkon should not be used on water-quality equipment (i.e. Van Dorn samplers, chemistry probes, etc.).
  • In 2014, Stantec tested the safety of Virkon for the NDR. This study found that airborne concentrations of Virkon® Aquatic are well below regulatory limits, but that employees should always wear nitrile gloves, chemical splash goggles and/or face shields when mixing solutions. The final report on the safety of Virkon® Aquatic can be found here:
  • The 2% Virkon Aquatic® solution should be disposed of by diluting to 1% or lower and disposed of as per site regulations. Please speak with the facility or lab manager to learn more about site regulations.
  • Dispose of unused Virkon® Aquatic in the sanitary sewer. When disposed of down a drain, Virkon® Aquatic uses oxidative mechanisms and will use any left-over product to oxidize organic sludge in the drain.
  • Use Virkon® Aquatic within 7 days post mixing because the product degrades. Test strips can be purchased to test the concentration of Virkon® Aquatic solutions.
  • The word “Virkon” and the date of mixing must be written on the container holding the solution.
  • Virkon® Aquatic and Virkon® Aquatic test strips are available from Western Chemical.
  • Always refer to the manufacturer.
  • S directions for additional guidance. The Safety Data Sheet (SDS) for Virkon® Aquatic can be found in the Additional Resources section.

Additional information: