Attachment 4 - Stormwater Managment Plan

Petroleum hydrocarbon waste: petrol, diesel, and motor oil (estimated 30
tonnes in drought to 58 tonnes in non drought of annual mass loading). Compounds
in petroleum hydrocarbons are highly toxic, and in the surface water environment,
they can cause harm to wildlife through direct physical contact, contamination by
ingestion, and the destruction of food sources and habitats. Bottom-dwelling or
bottom-feeding aquatic organisms may ingest petroleum contaminants and transmit
them up through the food chain until they accumulate in dangerous concentrations in
fish. Hydrocarbons also harm fish directly, and damaged fish eggs may not develop
properly. Additionally, oil can be particularly problematic because a single spilled cup
can contaminate the surface area of a water body the size of a football field.

Total Organic Carbon (estimated 356 tonnes in drought to 688 tonnes in non
drought of annual mass loading) This is a measure of the carbon bound in organic
material and indicates the oxygen demand created by organic material decomposing
in water. Sufficient levels of dissolved oxygen in water is necessary to maintain
aerobic conditions necessary to support aquatic life. The concentration of 59 mg/L
exceeds typical water guidelines of 10 mg/L.

Dissolved copper (estimated 1,800 kg in drought to 3,500 kg in non drought of
annual mass loading). Exposure to dissolved copper may be sufficient to impair the
sensory biology of some fish and has other toxic impacts to a wide variety of marine
life. Dissolved copper is also toxic to phytoplankton, the base of the aquatic food
chain. The concentration of .3 mg/L exceeds the ANZECC guidelines for 95% in
marine waters of .0013 mg/L.

Lead (estimated 121 kg in drought to 233 kg in non drought of annual mass loading)
Lead is a poisonous metal that can damage nervous connections (especially in young
children) and cause blood and brain disorders. In marine environments it can cause
anemia, depressed growth, fin degeneration and reduced egg hatching success. The
concentration of .02 mg/L exceeds the ANZECC guidelines for 95% in marine waters
of .004 mg/L.

Zinc (estimated 3,000 kg in drought to 5,800 kg in non drought of annual mass
loading) Zinc is most toxic to microscopic organisms in the aquatic environments.
The concentration of .5 mg/L exceeds the ANZECC guidelines for 95% in marine
waters of .015 mg/L.

Surfactants estimated 160 tonnes in drought to 315 tonnes in non drought of
annual mass loading). In surface water environments, surfactants are acutely toxic
to aquatic life, stripping fish gills of natural oils, thereby interrupting the normal
transfer of oxygen.

Suspended solids (estimated 1,200 tonnes in drought to 2,330 tonnes in non
drought of annual mass loading). Sediment, the most common pollutant in
stormwater runoff by volume and weight, makes streams and lakes less suitable for
recreation, fish life, and plant growth. Sediment is of particular concern in fish-
bearing streams where it can eggs, destroy habitat for insects (a food source for
fish), and cover prime spawning areas. It reduces the amount of light in the water
available for plant growth and thereby reducing the supply of food for other
organisms. The concentration of 200 mg/L is almost 10 times higher than the
ANZECC Guidelines in marine waters of 20 mg/L. Turbidity is the measure of the
cloudiness of water and has similar consequences to suspended solids. The measure
of 80 NTU exceeds typical water guidelines of 5 NTU.


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