How Boats Spread Invasives | Moving a Boat | Dry Time Estimator |
Watercraft Inspection Station Contacts | Watercraft Inspection Station Location Information |
State and Provincial Contacts | Commercial Boat Haulers | Wakeboard Ballast |
Boat Design and Invasive Species
How Boats Spread Invasives

Much of the ongoing spread of aquatic invasive species (AIS) to inland waters throughout North America can be attributed to the overland movement of powerboats, small commercial and recreational fishing boats, sailboats, personal watercraft, canoes and kayaks, pontoon boats, and other boats that can be towed overland on trailers. Translocation of organisms by boaters can be intentional (e.g., as bait), but is often unintentional, with invasive species inadvertently carried in bilge water, live wells, and bait buckets. Invasive species can also be entrained on boat exteriors, e.g., entangled on propellers and trailers, attached to other entangled organisms. Thus, every time a boat is transported overland after use in an infestedwaterway, there is the possibility that it will transfer aquatic invasive species to uninfested waterways.


Overland transport of small-craft boats is thought to be responsible for the spread of spiny waterflea (Bythotrephes longimanus), Eurasian watermilfoil (Myriophyllum spicatum), and zebra and quagga mussels (Dreissena spp.). These organisms are known to have considerable negative effects on the aquatic ecosystems they invade, with impacts including damages to fisheries, interference with raw water usage, decreased property values, extirpation of native species, and threats to human health.

Check out our photo gallery to better understand all of the places invasive species can hitch a ride on your boat or trailer.

*Note: The text above was excerpted from, "Aquatic Invasive Species Transport via Trailered Boats - What is Being Moved, Who is Moving It, and What Can be Done," J.D. Rothlisberger, W. L. Chadderton, J. McNulty, and D.M. Lodge, American Fisheries Society, 35(3):121-132.


Moving a Boat - Clean, Drain, Dry, Contact

If you are moving a boat:

  • CLEAN the boat - CLEAN all visible aquatic plants, zebra mussels, and other prohibited invasive species from watercraft, trailers, and water-related equipment before leaving any water access or shoreland. Washing your boat is a good first step, but remember that live mussels can be found up to 30 days after removal from the water - boats have many nooks and crannies where invasive species can hide. DISPOSE of unwanted bait, including minnows, leeches, and worms, in the trash. It is illegal to release bait into a waterbody or release aquatic animals from one waterbody to another. If you want to keep your bait, you must refill the bait container with bottled or tap water.

  • DRAIN the boat - DRAIN water-related equipment (boat, ballast tanks, portable bait containers, motor) and drain  bilge, livewell and baitwell by removing drain plugs before leaving a water access or shoreline property. Keep drain plugs out and water-draining devices open while transporting watercraft.

  • DRY the boat - Remember that live mussels can be found up to 30 days after removal from the water. How do you know if your boat is dry? Check out the Dry Time Estimator.

Dry Time Estimator

If a boat moved from an infested area will be launched in waters that are not infested with zebra or quagga mussels, the general recommendation is to keep the boat out of water and let it dry for a minimum of 30 days after cleaning all equipment and draining all possible sources of standing water. However, such "quarantine" times may be reduced depending on local temperatures and relative humidities.


In general, zebra and quagga mussels can survive longer out of water if local conditions are cold and humid than if conditions are hot and dry. This tool estimates recommended quarantine times based on average humidity and temperature zones in the 48 contiguous United States.


If a boat has been in infested waters, please use this tool to estimate the minimum time it should remain out of water (after being cleaned thoroughly), before launching in uninfested waters. Recommendations are only guidelines for average conditions and are based on evidence from laboratory experiments where other factors are held constant. Thus, recommended quarantine times may not produce 100% mortality under real-world conditions where unidentified, yet contributing factors are free to vary. This tool will provide a minimum quarantine time that you may need to adjust upward if your situation includes additional contributing factors that may be important.


Along with this tool, please use your best judgment before launching a potentially contaminated boat in uninfested waters.



Maximum Daily Temperature (°F)                                        Minimum Days Out of Water


                          30-40                                                                    28       (4 weeks)

                          40-60                                                                    21       (3 weeks)

                          60-80                                                                    14       (2 weeks)

                          80-100                                                                    7       (1 week)

                         >100                                                                         3   

Note: Add 7 days for temperatures ranging from 32 °F to 95 °F if relative humidity exceeds 50% (McMahon, pers. comm. 2009).



[1] Equation used to create the Drying Time Estimator is from U.S. Army Corps of Engineers Contract Report EL-93-1, June 1993, "Use of Emersion as a Zebra Mussel Control Method" by Robert F. McMahon, Thomas A. Ussery, and Michael Clarke, The University of Texas at Arlington.*

  • ALWAYS CONTACT the destination state or province to understand the laws and regulations that jurisdiction has for boats coming from other states. To minimize travel delays and ensure compliance with state law, an inspection of your watercraft will be scheduled in your destination state.

Locate western States and Provinces Watercraft Inspection Station Contacts HERE.
Locations of Watercraft Inspection Stations - Click on the map to view the locations of watercraft inspection and decontamination station details in western states and provinces.
State and Provincial Contacts

In addition, the following state and provincial Aquatic Invasive Species websites can provide you with additional information:





City of Bellingham, Washington




Lake Tahoe




New Mexico

North Dakota


South Dakota







AlbertaBritish ColumbiaManitobaSaskatchewan



Commercial Boat Haulers



To prevent the spread of aquatic invasive species, the Pacific States Marine Fisheries Commission, U.S. Fish and Wildlife Service, Western Regional Panel on Aquatic Nuisance Species, and others are making information available to boat haulers, auctioneers, marinas, manufacturers, and brokers to make it easy to comply with state, provincial and federal laws, prevent costly delays in transporting or selling boats, and help reduce the spread of aquatic invasive species. Locate information here.

Wakeboard Ballast

Aquatic nuisance species often hitch rides to other bodies of water on the boats, trailers, and equipment that people transport from place to place. Boaters and anglers can inadvertently transport aquatic invasive species in bilges, ballast water, live wells, or any other equipment that holds water. It is the responsibility of the boat owner/user to ensure ballast tanks and bags are drained and dry when moving the boat between water bodies.

What is ballast?


A ballast tank is a compartment within a boat, ship or other floating structure that holds water. Adding water (ballast) to a vessel lowers its center of gravity, and increases the draft of the vessel. A ballast tank can be filled or emptied in order to adjust the amount of ballast force. Small sailboats designed to be lightweight for being pulled behind automobiles on trailers are often designed with ballast tanks that can be emptied when the boat is removed from the lake or reservoir.

Ballast tanks

Wakeboard Ballast Tanks and Bags

Ballast water taken into a tank from one body of water and discharged in another body of water can introduce aquatic invasive species. Wakeboard boats are V-drive boats, i.e., an inboard boat with the engine placed backwards in the rear of the boat. More weight is in the back of the boat  to make wakes larger and steeper. Some wakeboard boat models are direct drive boats in which the engine is in the middle of the boat. Most wakeboard boats will have features, such as ballast, wedge and hull technology, that help to create large wakes. Ballast can take the form of hard tanks or soft bags, which are filled with water from the body of water the boat is being operated on.

Ballast bags are used to enhance the surf wake made by a wakeboard boat, and are typically filled and drained with a pump connected to a hose. Some ballast bags are designed for integration into an automated ballast system already in place in the wakeboard boat. When filling a ballast bag, it is recommended in most owner manuals  to “place the pump in the water keeping it clear of weeds and sand.” When draining, the instructions direct the boater to “place the hose of the pump over the side of the boat.” Because these bags are impossible to fully drain, if a ballast bag has been used in a water body that has tested positive for aquatic invasive species, it must be decontaminated prior to it being used on any other water, unless it

has been out of the water for 30 days or more. The water temperature of the decontamination unit must be lowered to 120ºF to prevent any damage to the pump or bags. 


Factory Installed Ballast Bags

All Moomba ballast boats and all but one model of Supra ballast boats have soft ballast bags that have factory installed reversible pumps. They have the same inlet and outlet through-hull drain port located on the bottom of the hull. Almost all of them come with an inboard engine and three ballast bags: two bags are located on the sides of the engine compartment and one in the center floor compartment. All of these bags have a quick connect on the intake and discharge hoses to easily remove them. Only one Supra model, the 242, 2011+, has one hard tank located under a ballast bag.

Other Examples of Ballast Bags

There are many other examples of ballast bags, many of which are uniquely shaped for specific wakeboard boat models.

Boat Design and Invasive Species

Design and Construction in Consideration of Aquatic Invasive Species (ABYC 2018)

Boats and associated equipment are considered to be major contributors to the spread of AIS. Boats that have come into contact with AIS waters can become a means of transportation of AIS through:

  • Standing water, which may contain AIS within the hull or water systems

  • AIS on the trailer or trapped between the boat and the trailer bunks

  • Attachment of AIS to the hull or components of the boat

  • Entrapment of AIS within the mechanical systems


Best Practices for Boat Design and Construction

  • Improve visual and physical access to areas subject to inspection and decontamination

  • Design wells and other areas for complete drainage

  • Implement external flushing ports

  • Seal strakes, keels, ribs, and other structural components

  • Design bilges to prevent water-trapping features

  • Select materials to allow complete drainage

  • Design features that facilitate inspection without the use of tools

  • Provide methods of identifying the location and function of through-hull fittings

Best Practices for System/Component Design and Construction

  • Design systems and components for complete drainage

  • Utilize universal flush inlet fittings

  • Provide methods to identify the location and function of through-hull fittings

  • Consider filtration devices for raw water systems

  • Select materials and coatings with consideration to the maximum temperatures that may result during decontamination

Best Practices for Propulsion System Design and Construction

  • Include AIS supplements in owner’s manuals

  • Standardize flush connections (e.g., common garden hose)

  • Utilize external flush adaptors or integrated flushing technologies

  • Utilize closed cooling systems (sterndrive/inboard)

  • Design easily drained raw water systems

  • Test engines to current decontamination procedures for adverse effects


Best Practices for Trailer Design and Construction

  • Incorporate labeled AIS flush ports or openings

  • Add standardized hose fitting at flush opening (i.e., garden hose)

  • Where possible, avoid square edges; rounded designs prevent corners that may trap organic material

  • Utilize open frame construction or self-draining tubular design

  • Components that are immersed in water during the normal launch and retrieval process, such as trailer lighting systems, should be self-draining or submersible

  • Components that are not normally immersed but which may come into contact with the high water temperatures and pressures of the decontamination process should be watertight and capable of withstanding exposure to 140°F

  • Incorporate a message to “Clean, drain, and dry the boat, trailer and equipment, removing any attached plant material or debris”

Additional Boat Specific Recommendations


NON-MOTORIZED WATERCRAFT - Canoes, rafts, kayaks, rowboats, paddleboats, inflatables, sculls, and other non-motorized recreational watercraft also require proper treatment.

  • Clean straps, gear, paddles, floats, ropes, anchors, dip nets, and trailer before leaving the water body.

  • Dry everything completely between each use and before storing.

  • Wear quick-dry footwear or bring a second pair of footwear with you when portaging between waterbodies.


  • Clean centerboard, bilge board, wells, rudderpost, trailer, and other equipment before leaving the water body.

  • Drain water from boat, motor, bilge, ballast, wells, and portable bait containers before leaving the water body.



  • Inspect and clean motor or engine, including the gimbal area; trailer, including axles, bunkers, and rollers; anchors; dock lines; and equipment before leaving the water body.

  • Drain live-wells, bait containers, ballast and bilge tanks, and engine cooling systems.



  • Inspect and clean hull, trailer, intake grate, and steering nozzle, etc.

  • Clean hull, trailer, intake grate, and steering nozzle, etc before leaving the water access.

  • Run engine 5 -10 sec to blow out excess water and vegetation from internal drive before leaving the water body.