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Portavoe Reservoir Essential Safety Maintenance

09 April 2014 16:33

NI Water is aware of concerns expressed locally regarding the essential reservoir safety maintenance work at Portavoe Reservoir. The work is part of a province wide scheme of works covering 17 reservoirs to mitigate against potential flooding risks and ensure all reservoirs under our control comply with the standards of current legislation. A major element of the pre planning for this work involved carrying out a detailed assessment of potential impacts on local flora and fauna and implementing an action plan to mitigate any such impact. This process included close liaison with other agencies including DCAL, DARD Rivers Agency and NIEA.

The proposed works are a requirement of the Section 10(6) Recommendations in the Interests of Safety made within the 2006 Section 10 Inspection Report on Portavoe Reservoir.  The Report was completed by an All Reservoirs Panel Engineer under the 1975 Reservoirs Act.  However, the works are considered urgent as the timescale for completion of work to resolve matters in the Interest of Safety, as stated within the Act is as soon as reasonably practicable.

The draining of the reservoir commenced in October 2013.  Controlled discharges from the reservoir were limited by the requirements of the Flood Risk Assessment (FRA), approved by DARD Rivers Agency, the Article 226/2277 Discharge Consent, approved by Northern Ireland Environment Agency, the Habitats Regulations Assessment (HRA) and the Scour Management Plan for the site.  However, catchment inflows into the reservoir were high over the winter period and the water level did not begin to significantly reduce until February of this year.  

The environmental risks were considered and as a result a Habitats Regulations Assessment, in accordance with the requirements of the EC Habitats Directive, to assessment the impact on the downstream Outer Ards Special Protection Area has been carried out for the proposed works.  This process included consultation with the Natural Heritage team within Northern Ireland Environment Agency.  Northern Ireland Water has also continued to undertake its daily operations (as its normal practice) fully aware of its obligations under the Wildlife (Northern Ireland) Order 1985 (as amended) and its duty to conserve biodiversity under the Wildlife and Natural Environment Act (Northern Ireland) 2011.

DCAL, who stock the fish for angling purposes, have been working with Northern Ireland Water on this issue since June 2011 and will undertake to remove fish when the reservoir is no longer able to provide a suitable habitat.  Information on the draining of the reservoir, its impact on the fish stock, and advice for anglers has been in the public domain for over a year on the NI Direct Website.  

Northern Ireland Water has held numerous consultation exercises with NIEA since 2011 on the project.  This has included consultation with Natural Heritage, Water Management Unit, Water Framework Directive and licensing teams.  Northern Ireland Water has also carried out consultation with other statutory bodies including the Department for Agriculture and Rural Development Rivers Agency.

The viability of providing a cofferdam structure has been investigated but wasn’t feasible due to the associated costs, extra plant required, noise pollution and the time to complete the works would have been greatly increased.

Northern Ireland Water has always sought to operate and maintain Portavoe Reservoir in a manner sensitive to the benefits that it provides to the local area, community and environment.  Extensive consultation with appropriate environmental stakeholders has taken place to ensure that the unavoidable consequences of the works have been managed and that all necessary approvals have been obtained.  

Specific environmental assessments and applications have included:
  • A Habitat Regulations Assessment (HRA) was completed to verify that there would be no adverse impacts to the European designated Special Protection Area (SPA) of ‘Outer Ards’.  This assessment included consultation with NIEA Natural Heritage.  
  • A Water and Sewerage Service (NI) Order Consent Under Section 226/227 under the Water (Northern Ireland) Order 1999 was approved by NIEA Water Management Unit.
  • A Flood Risk Assessment was produced to ensure that the controlled release of water from the reservoir 
  • A Scour Management Plan was developed to ensure that the lowering of the reservoir was completed in accordance with the above applications.

Specific environmental mitigation measures incorporated into the works include:

  • Formalised downstream mitigation and monitoring points to ensure that the release of water from the reservoir does not have an adverse impact on the downstream environment and in particular the Outer Ards SPA.
  • The collection and translocation of swan mussels for temporary storage and ultimately re-seeding back into the reservoir on completion of the works.  
  • In coordination with DCAL a ‘catch and keep’ policy has been in place for the last year to reduce the fish stock within the reservoir.  DCAL will continue to monitor the site during the lowering works and rectify any fish welfare issues on site, should they arise.
  • Measures to ensure that no destructive site clearance works are being undertaken during the bird breeding season.  Birds nesting in vegetation surrounding the reservoir should be unaffected by the works, as should any birds associated with the stream into which the reservoir discharge is made.
  • Pollution prevention measures to ensure that the reservoir catchment and associated environment is not polluted or contaminated as a result of the construction works.  These include measures to prevent the infestation of non-indigenous invasive species such as zebra mussel.
  • On completion of the works it is anticipated that all fringe vegetation will return to normal without permanent effects.

Since the drainage of the reservoir has begun any impact on fish, birds and other flora and fauna has been closely monitored and kept to a minimum. Descriptions of the drainage work having led to “an ecological disaster” are completely unfounded. NI Water will continue to monitor the site closely along with colleagues from DCAL to ensure this situation continues.

NI Water will also collect a proportion of live mussels and hold them within tanks for re-seeding post works, an approach discussed and agreed with NIEA. It has made arrangements with DCAL to ensure any fish remaining in the reservoir as water levels drop are collected. Similarly no destructive work is being undertaken during bird breeding season. Birds nesting in vegetation surrounding the reservoir should be unaffected by the works.

Once the work is completed, the reservoir will be refilled with both fish and mussels being restored to their habitat.  It is hoped that the whole process will take approximately ten weeks. It should be stressed that once completed the works should ensure that the reservoir scour valve and drawoff tower will be operable for at least the next 25 years and minimise the risk of any future planned maintenance related lowering of the water level.

We are also aware of speculation that the work being undertaken is in some way linked to plans for the sale of the reservoir. NI Water can categorically confirm this is not the case.

NI Water would point out that this work is solely designed to maintain the highest standards in relation to the safety and good maintenance  of what we know is a highly prized local facility.  

Under our operating licence we have a statutory obligation to dispose of surplus assets.  Portavoe reservoir is one of a number of assets across the province that has been identified for possible disposal during 2014/15. In the first instance NI Water will make every effort to transfer ownership within the public sector for example to local councils. It would only be after all avenues in this regard have been explored that the potential for sale on the open market would be considered and even then this would involve full consultation before any decisions were taken.

Our wish is to ensure that when this work is completed it will provide a safe and well maintained facility which will continue to provide pleasure to all who use it for many years to come.


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