International Water Ski Federation
Environmental Handbook for Towed Water Sports
Like most human activities, water skiing
causes a certain degree of impact to the natural environment in which it takes
place. Whether that impact is
negative, neutral or potentially even positive is often a matter of some debate.
Studies and reports rarely come to the same conclusions concerning either
the degree of impact or the relative priority of any one issue as opposed to
another. Several major studies
undertaken in Europe and the United States conclude that in general, and
relative to other boating activities, water skiing does not significantly impact
the natural environment. On the
other hand, various studies and one book in particular conclude that boating
(more so than water skiing) does have a significant ecological impact,
particularly in regards to certain environmental issues.
Rather than enter
into this ongoing debate, the following pages focus instead on the most commonly
cited and studied environmental impacts associated with boating and water
skiing, drawn from the literature review.
The objectives of
this section are to provide the reader a description of what impacts are associated with boating and water skiing, and
secondly, how these impacts affect
the environment as well as human, animal and plant life.
THE WATER CYCLE— HOW WATER SKIING IS GLOBALLY CONNECTED
What would water skiing be without
water, moreover, without CLEAN water?
We are all globally connected through
nature’s ecological cycles, in particular the water cycle, also known as the
hydrological cycle. Through a variety of unique natural processes all of
earth’s water supplies, be they from rivers, icecaps, oceans or seas,
eventually evaporate into the atmosphere to become part of a continuous
phenomenon called the hydrological cycle. Those raindrops that cause you to
cancel a day of water skiing are actually part of a much larger and vital
natural process, one that all living beings depend on for survival.
When unnatural substances, like hydrocarbon emissions from the burning of fossil fuels, enter the hydrological cycle they have a detrimental effect on earth’s ecosystems, and human health. This is evident from the damage created by acid rain and greenhouse gases which are the products of human activity.
The main environmental impacts associated with boating and water skiing fall into four key categories:
Noise – engine and human noise
Pollution – chemicals, gases, solid wastes, and biological contamination
Geomorphology and Hydrology – shoreline and flora degradation, and turbidity
Birds and Wildlife
– disturbance and dislocation
Some of the more common types of impacts
associated with these categories include:
Noise pollution – from boat movement on the water and the club/marina grounds
Emission of harmful gases, gaseous products and particulates from marine engines
Emission of hydrocarbons into water body, ground water, lake sediments and atmosphere
Release of potentially toxic heavy metals in the water
Increased water turbidity due to the engine, boat and even water skier
Clogged intake valves from biological contaminants such as zebra mussels
Creations of excess garbage on land and water
Disturbance of birds and wildlife due to boating activity and noise
most of the above impacts are negative, there are also some benefits of both
water skiing and boating on the environment.
In some instances,
boating and water skiing can directly benefit
the ecosystem by adding much needed oxygen to the water body.
Studies have indicated that the action of the engine propeller, the boat
hull, and the water skier cause an increase in the oxygen content in the water.
This in turn can benefit the health and diversity of the animal and plant
life living in that water. This
oxygenation process is most advantageous in shallow waters, waters that have
minimal fresh water exchange and a high incidence of algae growth.
Another benefit of
water skiing and boating is the removal of carbon dioxide, and other pollutants,
from the water body. This benefit
is credited to marine engines with underwater exhausts.
As the bubbles containing the exhaust gases are dispersed behind the boat
they help to reduce noise and to transport emissions to the surface where they
are evaporated. An underwater study done by Outboard Marine Corporation found
that air bubbles moving through the water at high speeds can help to degrade
waterways, especially canals, a low density of regular boat traffic discourages
the overgrowth of potentially troublesome plant species, and helps maintain a
diversity of native plant species. In
addition, the restoration of disused canals and open pit mining quarries for
water based recreation has benefited many types of wildlife and waterfowl.
some cases the presence of water skiing has led to significant enhancements to
the local ecosystems. In one region
of the United Kingdom, a local water ski club, together with the region’s
conservation authority implemented a comprehensive remediation strategy to
protect both plants and animals along a stretch of river.
Some of the actions taken included the introduction of native plant
species, the construction of natural berms and islands, the implementation of
strict no-pass zones along certain shorelines, and the creation of a slalom
course a safe distance from nesting areas. The enhancements would most likely
not have taken place if the water ski club had not initiated them.
When compared with
many other types of human activities, water skiing is not particularly noisy.
The typical, older two-stroke, 68 horsepower engine, operating under
normal water skiing conditions produces a range between 60 to 70 dBAs.
values help put this range into perspective relative to other types of common
· 120 dB(A) Discotheque – 1m in front of loudspeaker
· 100 “ Pneumatic drill at 5 m
· 70 “ Telephone ringing at 2m
· 40 “ Refrigerator humming at 2m
Unfortunately, in many parts of the
world water skiing still has a reputation for being a noisy and dangerous sport,
often more so than other watercraft activities. Recent studies on engine noise undertaken in different
countries have shown that the typical water ski boat engine produces a level of
noise well below the national standards for noise, and frequently below that of
In recent years, marine engine
manufacturers have taken significant steps to reduce the level of noise created
by their motors (refer to Appendix B on Marine Engines for more details).
This move towards quieter technology should help to counter the image
that water skiing and boating are excessively noisy.
The British Water Ski Federation has
produced one of the most thorough and widely used documents on noise entitled
“Code of Practice for Water Skiing & Noise” (1997).
Table 1 reveals the BWSF’s standards for noise emissions for water skiing:
 dB(A) – dB stands for decibel, which is a logarithmic scale used to measure sound. ‘A’ means it is a weighted decibel which is an internationally accepted unit for most noise measurement, and represents the sound pressure level weighted to correspond to the frequency response of the human ear.
It is important to remember that noise
is a SUBJECTIVE, and SENSITIVE issue -- what is offensive to some may not be so
to others. It is wise to approach
all conflicts related to noise disturbance with sensitivity.
Always respect others’ right to peaceful enjoyment of their property
and common waterway.
A recent trend of concern is the
increase in boat and jet ski stereo systems with large amplifiers. As sound
travels much farther on water, skiers and boaters should make sure to keep the
volume low and respect other’s privacy when on the water. This additional
source of noise could be a detriment to the image of boating and water skiing if
allowed to get out of hand.
It is responsible boating to always abide by the club/marina’s Code of Practice for Noise. If your club/marina does not have a Code, a copy of the BWSF’s can be obtained and customized for your club/marina.
2. POLLUTION – Chemicals, Gases, Solid Waste, and Biological Contamination
Despite the best efforts of responsible
boaters to prevent water contamination, gasoline and oil exhaust, namely
hydrocarbons, are released every time a marine engine operates.
Depending on the type of engine used, the degree of such pollution will
Have you ever wondered what a few hours of boating fun and water skiing activity may be doing to the water we swim in and the air we breathe?
On an individual basis the impact of
your boat and skier on local ecosystems is minimal. However, over time, and
considering the combined effect of thousands of other boaters and water skiers
around the world, the impact can be significant.
Consider what the typical marine engine
emits from a few hours of water skiing activity.
Typical Two-Stroke Boat Engine and its Emissions:
The impact of a two-stroke, 68
horsepower outboard (built before 1997) mounted on a 17 to 21 foot planing
runabout boat hull -- at the lower end of boats commonly used by recreational
water skiers -- serves as a useful illustration.
During a three to four hour afternoon of
water ski and boating activity this two-stroke engine will consume about:
20 gallons (80 litres) of gasoline and
3.5 pints (2 litres) of lubricating oil.
approximately 30 percent of the "unbent" (see Table 2) gasoline will be
emitted directly into the water during operation.
Estimates for the United States alone
are that 567 million to 1.6 billion
litres of unburned fuel is exhausted into the environment each year by 12
million gasoline powered pleasure boats (1993 figures).
Boat Engine Exhaust
WHAT Happens to Boat Exhaust?
Hydrocarbons end up in the water column,
in the bottom sediments, as surface film, or released into the atmosphere.
Atmospheric hydrocarbons are also a prime cause of greenhouse gases and
thinning of the ozone layer. Furthermore,
both burnt and unburned fuel contain compounds, like polycyclic aromatic
hydrocarbons, that are toxic to aquatic organisms and are linked to human
illnesses like asthma, cancer, and genetic mutations.
However, there is considerable evidence
to indicate that marine engine exhaust does not cause permanent damage to the
aquatic environment. In particular,
evidence of hydrocarbon accumulation in the sediment is inconclusive, and lead
concentration is not thought to be significant. It is therefore most likely that the majority of the exhaust
emissions are ending up in the atmosphere, where they are quickly dispersed.
This may be good news for the local marine ecosystem but not for global
All man-made materials abandoned either
on land or in the water can be considered waste, or more commonly, garbage.
Not only is waste unsightly, it reduces the esthetic appeal of a
club/marina and its grounds and waterways, and is a hazard to wildlife, birds
and even children. Some wastes,
even though they are biodegradable, will persist for many years. Those wastes
that are not made of natural materials will either break down and leach minute
toxic elements into the soil and groundwater or they will persist for decades
and even centuries.
To sort, haul, and dispose of wastes
costs the club/marina and governments considerable amounts of money that could
be better spent for more productive purposes.
Fortunately, wastes are one of the
impacts that club/marina operators can address through a waste prevention plan
and Codes of Conduct (addressed in Part D).
Individuals also play an important role
in the success of the waste prevention plan.
Part C offers several suggestions on ways individual water skiers and
boaters can prevent wastes, and dispose of them properly.
contamination is a term used to describe unwanted, non-native organisms, both
plant and animal, that can invade aquatic ecosystems. Water skiers can
unwittingly play a role in spreading these species when boats and watercraft
move from one water system to another without taking proper precautions to
cleanse themselves of these unwanted "hitchhikers".
The zebra mussel
is one such organism that has wreaked havoc in many water systems throughout
North America. The mussels attach
themselves to boat hulls and propellers, intake and outtake valves, and water
ballast tanks and spread rapidly once relocated to a new body of water.
The plant contaminants, such as hydrilla, hyacinth and milfoil, can
spread in a similar manner as the zebra mussels.
also cause an increase in fuel consumption, a decrease in native plant diversity
and survival rates, deoxygenation of the water body, loss of fish life and other
aquatic species. They can also
prevent the safe use of a body of water for recreational activities like water
skiing or swimming as the water becomes so clogged as to be impassable.
Many of these biological contaminants are difficult and costly to remove.
information on the different categories of pollutants, their harmful effects,
and points of control both on and off the water please refer to Appendix A.
Shoreline erosion, degradation of
shoreline flora, and turbid water (unclear or sediment-filled) are natural
phenomena resulting from wind action and hydrological activities.
They are also directly affected by human, water-based activities such as
boating, water skiing, and docking.
Compared to all factors, such as weather
and other watercrafts, recreational boating activity has been shown to
contribute minimally to erosion and
turbidity. However, some studies
have shown that if water skiing and boating are practised too close to shore,
and in environmentally sensitive areas, the impact from boat and skier wash can
Determining the degree of impact is
complex and often involves any combination of factors from the number of boats,
to the shape of the boat hull, to the speed of the boat, to the depth of the
water, and the distance the boat is from shore.
considering the causes of erosion and turbidity both natural phenomena and
seasonality must be taken into account. Wind
action is a major contributor to both and has a greater impact during the winter
season when weather conditions can be a great deal rougher. Other factors that will influence erosion and turbidity
include the form and composition of the soil, the shoreline gradient, and the
degree of natural or artificial protection.
The degree of damage can be severe at sites which have unstable soils, or
generally weak vegetative growth.
Turbidity is caused when engine
propellers and boat wash stir up bottom sediments in shallow waters and the
particulates remain suspended in the water column.
The degree of turbidity is directly proportional to the depth of the
water, i.e. the shallower the water the greater the turbidity levels.
BIRDS and WILDLIFE – Disturbance and Dislocation:
Considerable research has been
undertaken in different countries to determine if and how boating and water
skiing affects birds, namely waterfowl. Considerably
less work has been done on the impacts on wildlife.
In general, the majority of boating and
ski activity that takes place 50 metres or more from shore usually does not
cause any significant impact to birds and wildlife. However, where the disturbance and dislocation is often the
most serious is:
In narrow bodies of water
With sensitive species
When boaters and skiers pass repeatedly too close to shorelines inhabited by birds and wildlife.
Shorelines with poor vegetative cover
Birds, particularly waterfowl, nest
close to shorelines and are especially vulnerable when molting (losing feathers).
As each water body will have different characteristics related to types
of species, nesting habits, and seasonal factors, it is difficult to generalize
on the impacts. However, what is
known is that in areas where waterfowl disturbance has been recorded, the types
of impacts can include relocation of nesting site, abandonment of nest, and loss
of young. There can also be long
term impacts as many species of birds that normally would return year after year
to the same nesting area are forced elsewhere to perhaps less desirable bodies
In general, measures to protect
waterfowl are also beneficial in protecting wildlife.
In summary, it
can be said that all of us have a responsibility to ski and boat with care and
to show respect for the environment and all the living things in it.
With that goal in
mind a universal motto for the water ski community could be:
Back to Index
Introduction - Part A
Practical Steps to Environmentally Responsible Water Skiing and Boating - Part C
Recommended Best Practices for Club/Marina Operators - Part D