Sewage, Grey Water and Rubbish
Sewage
Untreated
sewage from boats can spread gastroenteritis; contaminate shell
fish beds and mussel ropes and use up vital oxygen in the water.
Human waste also contains phosphorous and nitrogen which increase
the levels of algae and reduce water clarity. Chemicals such as
chlorine, formaldehyde, ammonium and zinc compounds used as
disinfectants, breakdown and deodorise waste are toxic to marine
life.
Discharge of boat sewage to coastal waters is regulated under
MARPOL Annex 4 and whilst this only applies to recreational
craft carrying 15 or more passengers, you only need 3 boats (with 5
crew in each) in a rally to cause a similar amount of damage. So it
is certainly worth considering using your holding tank when out and
about.
Sewage
discharge from vessels in rivers, canals and lakes is regulated by
many authorities and byelaws and although there may be varying
local byelaws it is generally prudent to assume that discharges are
not permitted.
Since
2006 the Recreational Craft Directive, applied to newly built
vessels, has required provision to be made for a holding tank
to be fitted. If buying a new boat consider having the holding tank
installed by the manufacturer.
Best Practice Advice
Leaflets & Resources
Green Products
Grey Water
Grey
water discharge from sinks, showers and washing machines can be
very damaging to sensitive aquatic life. Most washing detergents
contain phosphates which encourage rapid algal growth and eventual
oxygen depletion when the algae die and start to break down.
This eutrophic effect can cause fish and other aquatic life to
suffocate.
Added to
this, the degreasers found in washing up liquids and soaps strip
the natural oils from fish gills making it difficult for them to
breathe.
On the
inland waterways, it is a requirement under British Waterways
licences that only phosphate free detergents may be used.
Best Practice Advice
Leaflets & Resources
Green Products
Rubbish
Marine litter has a major
impact on wildlife, the main issues being entanglement and
ingestion. It is estimated that over 50,000 marine mammals die
every year from becoming tangled in or eating marine litter.
Plastics are the most
prevalent beach litter material. Certain types of plastics are
known to absorb chemicals from the surrounding environment, such as
PCB's and heavy metals at concentrations up to 1 million times
higher than in waters around them. The ingestion of these toxins
can have life threatening impacts upon marine wildlife.
Research shows that
little of the litter entering the marine environment comes from
marine boating; the 2007 MCS beach watch survey identified the
main contributers as beach visitors (35.3%) and the fishing
industry (13.7%).
However boaters are
likely to be more aware of litter than other groups and should
still do their part to prevent any litter from
entering the water.
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