HBC GOLDEN YEARS SOCIETY INCORPORATED ( FISHING GROUP)

A SUBMISSION FROM THE SOCIETY OBJECTING TO THE PROPOSED TIRI MARINE RESERVE

While the members of this fishing group naturally are concerned with the restrictions a marine reserve would impose on the rights of its members to fish for food within the proposed marine reserve in an area at the end of the Whangaparaoa Peninsular and in particular because a substantial no fishing area already exists within the cable area to the East of Tiri Island, they feel that a greater threat to the marine environment already exists within the proposed area of the reserve.

The NZ Underwater Association surely must have not taken into account the future discharge of treated sewage effluent when putting forward its proposals to site a marine reserve at the end of the Whangaparaoa Peninsula into the middle of which treated sewage effluent will be discharged in substantially increased volumes in the future.

If the Association feels it is desireable or necessary to establish a further marine reserve, it must find a more suitable area than that proposed by them.

We have been told by the Rodney District Council that sewerage from Orewa will be directed to the Army Bay plant for treatment before discharge into the sea at the end of the peninsular by the end of 2004. Whangaparaoa and Silverdale sewerage already goes there.

Council will soon be under enormous pressure to open up residential subdivisions of land at Silverdale and to the West of Orewa, Hatfields and Waiwera which area is ripe for development now that there is a motorway to Auckland city, city water and ,sewerage disposal to be shortly available to serve those areas.

A report in the”Times” newspaper dated 23 Jan.2003 tells us that The Rodney District Council will soon publicly release a concept plan which,if approved, will open the Silverdale North area to massive development providing for a home for almost 7000 extra people

The present average sewage effluent discharge into the sea from the Orewa ponds off Red Beach is about 4000 cubic metres per day released on an outgoing tide (RDC briefing paper 6 –Existing system performance15/2/02) to drift along the coast to the North from a population of about 9000 people. Using the same 2001 census figures, showing the population of the entire Hibiscus Coast at about 32,000 at that time, the daily discharge of treated sewage effluent into the Tiri channel will average 15000 –20,000 cubic metres per day when the two sewerage systems are connected.. This figure is bound to double to about 40,000 cubic metres per day by the year 2031 taking into account the Council’s estimate of projected total Hibiscus Coast population growth to 62,000 by that date.. A resource consent to discharge up to 51,000 cubic metres of treated sewage into the Tiri channel to cater for a population of 81,000 in 50 years time has already been applied for but,we understand,,has not yet been approved.

It is known that large quantities of sewage effluent rises rapidly to the surface in a series of “boils”and that these boils combine to form a surface layer of diluted effluent that spreads out over the surrounding seawater and forms a plume in a down wind or down current direction

Marine algae have the potential to form toxins which are detrimental to marine life.An example of these are “Red Tides” , a marine algal growth which causes shellfish to become poisonous and fish to die.
Already we have been told of reports late last year giving evidence of fish dying due to suffocation following gill contact with algal blooms encountered along the coast between Martins Bay (discharging sewage effluent from Snells Beach / Algies Bay) and Orewa presumeably nourished by nutrients in sewage effluent plumes entering the sea at these places.

Information supplied to the writer by the RDC indicates that between Oct.2001 and Oct 2002,
a study showed that of the treated sewage discharged into the Tiri channel over that period an amount of suspended solids not filtered out by the Army Bay treatment plant before discharge into the sea has been analysed to contain anywhere between 16 and 25 milligrams per litre of treated sewage effluent. At 25 milligrams per litre a discharge of 51000 cubic metres weighs in at 1275 Kilograms of suspended solids discharged into the sea each day These solids combine with a residue of faecal coliforms,,heavy metals, toxic chemicals.oils,detergents and other pollutants from industrial commercial and domestic processes.before discharge into the sea. It is known that these materials can survive the treatment process. Even if a way to halve this quantity before the maximum discharge applied for is reached, a daily discharge of 600 kilograms of suspended solids together with the faecal coliform content and other pollutants in the treated effluent which collectively will no doubt be eaten by any fish in the area is far too much and may be the cause of algal blooms fatal to the life of fish . In the same study an average of 80,000 with a median of 39,000 MPN Faecal coliforms per 100 mls.were found in the treated sewage discharge.

Members of our fishing group have experienced strong chemical odours when gutting fish caught in the vicinity of the treated sewage outlet into the Tiri Channel .resulting in the fish being dumped rather than being taken for food.

In addition a daily discharge volume of up to Council’s estimated future 51000 cubic metres of treated effluent will contain enormous amounts of fresh, (although contaminated) water. This must effect the salinity in the seawater which , if not be detrimental or even fatal to sea life, will surely drive the fish away to more distant areas outside the proposed reserve. No place for a marine reserve at all!

Guardians of the Coast spokesperson, Allan Parker, in his article in the “Coaster” newspaper published on Feb.5th 2003 has correctly demonstrated that the tidal streams flow North and South through the Tiri channel over a 12 hour cycle with the rise and fall of the tide and that the same body of water is moved back and forth through the channel during this cycle.The movement of the tide is stationary for two periods of half an hour each day with the tide flowing nowhere.The effluent is not discharged on an outgoing tide only as this would involve building holding tanks or ponds at considerable expense to cope with the volume effluent which would otherwise be discharged on a continuous basis. In agreeing with Allan’s statement one must conclude that there will inevitably be a huge percentage increase of treated sewage effluent mixed with seawater in the Tiri channel in future years .

Why would anyone wish to establish a marine reserve anywhere near the proposed Tiri channel area knowing that these serious problems could occur in that area in the future,

The proposal for a Tiri reserve proposed by the NZ Underwater Association must be abandoned now before any further action is taken to establish it.

(John Donaldson)
Secretary, HBC Golden Years Society (Fishing Group)
Email:johndonaldson@paradise.net.nz