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Here in Minnesota boating is a favorite pastime. Whether we are fishing, water-skiing or just cruising around, being on and around the water is a big part of most of our lives. With increased development and bigger boats on the water, we all have to be more aware of keeping our lakes clean and safe. In order to use our resources wisely, we all need to be educated as to how our actions affect the environment and the experience of others. Here you will find information on how to enjoy the lakes while being a responsible boater.


The Duluth News-Tribune reported in 2000 that horsepower has doubled on new boats registered in MN between 1981 and 1999. Minnesota lakes have also seen an explosion in the use of personal watercraft (jet skis). Personal watercraft are small and powerful and are able to access areas that are not accessible to regular boats. This increased access brings on a whole suite of problems for aquatic ecosystems. Some of these problems include disturbance of sediment, vegetation, fish and wildlife in shallow near-shore areas. Here are some of the ways in which boats can affect the aquatic environment:

Water Clarity - Propellers may disturb the lake or river bottom directly, or indirectly through the wash or turbulence they produce, especially in shallow water. This may affect water clarity by increasing the amount of sediment particles in the water or may cause nutrients that are stored in the sediments, such as phosphorous, to become available for algal growth. Waves created by watercraft may contribute to shoreline erosion, which can cloud the water.

Water Quality - Two-stroke engines, which make up the vast majority of the motors in use on all types of watercraft, are terribly inefficient. Estimates vary as to how much fuel may pass into the water column (25-30% is a reasonable average) and depends upon factors such as engine speed, tuning, oil mix and horsepower. Other concerns include lowered oxygen levels due to carbon monoxide inputs, and spills or leaks associated with the transfer and storage of gasoline near water bodies.

Shoreline Erosion - Shoreline erosion may affect water clarity in near shore areas, shading submerged aquatic plants as well as providing nutrients for algal growth. It can interfere with fish use of shallow water habitat, as well as wildlife use of the land-water edge. Excessive shoreline erosion can negatively affect property values and can be expensive for riparian landowners to prevent and control.

Aquatic Macrophytes - Boats may impact macrophytes either directly, through contact with the propeller and boat hull, or indirectly through turbidity and wave damage. Propellers can chop off plant shoots and uproot whole plants if operated in shallow water. Increased turbidity from boat activity may limit the light available for plants and limit where plants can grow. Increased waves may limit growth of emergent species. Finally, boats may transport non-native species, such as Eurasian water milfoil, from one body of water to another.

Fish - Direct contact of boats or propellers may be a source of mortality for certain fish species, such as carp. Pollution from exhaust or spills may be toxic to some fish species. Boat movement can affect individual fish directly by disturbing normal activities such as nesting, spawning or feeding. Increased turbidity from boats may interfere with sight based feeding or success of eggs or fish spawning. On a population level, boats may affect fish through habitat alteration caused by waves or propeller damage.

Aquatic Wildlife - Boats may have direct impacts on wildlife through contact with propellers or disturbance of nests along the shoreline by excessive wave action. Disturbance by the fast movement of watercraft or even the presence of humans near feeding grounds or breeding areas may prevent certain species, especially birds from being successful. Noise or harassment may cause some wildlife to vacate nests, leaving eggs or young vulnerable to predators. Indirect effects may include destruction of habitat or food source in littoral areas, or impaired water quality.

Personal Watercraft ("Jet Skis") - Personal watercraft (PWC) have many of the same effects as previously described. However, because of their unique propulsion systems and use characteristics, this special section has been included to summarize studies that have addressed the impacts of PWCs specifically. For example, PWCs are often criticized for the noise that they produce, due to their frequent stops and starts and operation at full throttle. Most PWCs employ two-stroke technology for their engines, thus making them a concern for their air and water emissions of hydrocarbons and other pollutants. Because PWCs can be operated in shallow water, at high speeds, and in remote areas not usually frequented by boats, disturbance to wildlife may be more of a concern than other types of watercraft. Finally, while PWCs do not generally have propellers, the turbulence produced by the jet propulsion may still disturb plant growth and sediments, especially during acceleration or turns when the thrust may be oriented downward.

A report was published in July 2002 by the American Canoe Association ( regarding the apparently disproportionate number of accidents associated with PWC's [ Hostile Waters - 923 KB pdf file ]. We were not able to find a formal critical review of this report by the PWC Industry but did receive a copy of a seven page response to Hostile Waters from the Personal Watercraft Industry Association (PWIA). We also list the most relevant websites that we could find for one to find the "Industry" perspective regarding proposed regulations and environmental impacts associated with their use (in particular the PWIA website at

What can be done to reduce these impacts?

No wake zones in shallow areas of lakes and rivers could help to reduce impacts on water clarity, bank erosion, fish, wildlife and aquatic macrophytes. In some cases it may be beneficial to restrict boat activity altogether, such as in extremely shallow waters where boats can disturb the bottom even at no wake speeds.

Cleaner technology, such as four-stroke engines, and more efficient two-stroke models should help to reduce the inputs of fuel and exhaust into water bodies over time. Keeping engines well tuned and using manufacturer's recommended mix of oil and gasoline would help engines run more efficiently and reduce the amount of unburned fuel that is discharged.

Check out the Minnesota Department of Natural Resources Minnesota Boating Guide. Keep a safe distance from other lake users and always obey no wake zones and hazard areas. Also, be aware of weather conditions at all times. If bad weather arrives get off of the water and take cover. Hypothermia (below normal body temperature) is an insidious killer that is involved in perhaps as many as one-half of Minnesota's boating deaths each year. Immersion in cold water (less than 70 degrees Fahrenheit) causes the body to lose heat faster than it can produce it, decreasing the body's inner (core) temperature. This decrease can cause symptoms ranging from continual shivering, poor coordination, and numb hands and feet in moderate cases to hallucinations and eventual death in most extreme situations. Cold water robs body heat 25 times faster than air of the same temperature, so if you capsize or fall out of your boat, immediately attempt to re-board your craft.


Much of this information has been adapted from:
The Wisconsin Department of Natural Resources Report, The Effects of Motorized Watercraft on Aquatic Ecosystems by Timothy R. Asplund, this article is an excellent review of several studies on the effects of watercraft on aquatic habitats.

The National Clean Boating Campaign

The American Canoe Association's website has information on paddling safety, navigation, weather watching, conservation, education and local and national events.

The U.S. Power Squadron Minnetonka Chapter website has information on several education programs available locally.

For local boating information including lake access, special regulations and maps, check out the following websites: Lake Minnetonka Conservation District , Minnesota DNR , Hennepin Parks and Met Council.

Personal Watercraft Concerns
Hostile Waters: The impacts of personal watercraft use on waterway recreation, July, 23, 2002. David Jenkins, American Canoe Association, 7432 Alban Station Blvd, Suite B-232, Springfield, VA 22150. [ PDF file, 923 KB ]

PWC industry perspectives and links:
Personal Watercraft Industry Association,1819 L Street NW, Suite 700, Washington, DC 20036,

Personal Watercraft Industry Association Responds to American Canoe Association Accusations: Just the Facts pdf document. This is a 7 page handout that was distributed at a meeting in which the author of Hostile Waters spoke sometime in late summer 2002. We did not find it on the PWIA website but have reproduced a copy sent to us by the ACA.

American Watercraft Association, 27142 Burbank Foothill Ranch, CA 92610,

National Marine Manufacturers Association,

Information about motorized watercraft impacts on lakes
Minnesota Lakes Association:

Wisconsin Dept. of Natural Resources: The Effects of Motorized Watercraft on Aquatic Ecosystems by Timothy R. Asplund, this article is an excellent review of several studies on the effects of watercraft on aquatic habitats.

US EPA National Management Measures to Control Nonpoint Source Pollution
from Marinas and Recreational Boating


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