Wairoa River is in the spotlight, after information revealed three organisations breached resource consents nearly 20 times over an 18-month period.
Information sourced by the Wairoa Star under the Official Information Act shows a series of consent breaches into the Wairoa River by Affco, Wairoa District Council and Silver Fern Farms from the start of last year to June of this year. Affco had 10 breaches related to water quality and three technical non-compliances not related to water quality. The breaches relate to the breakdown of discharge measured by the depletion of dissolved oxygen by biological organisms in a body of water in which the contribution from nitrogenous bacteria has been suppressed.
The Wairoa District Council occasions related to breaching its Chemical Oxygen Demand (COD) measures five times.
The Silver Fern Farms issues were based around four water quantity and quality breaches, including a possible false reading.
Hawke's Bay Regional Council resource management group and resource use manager Wayne Wright said consent conditions were set to ensure environmental effects were minor.
In October 2012, the regional council requested Affco Wairoa provide a health risk assessment on the impacts of its wastewater on the Wairoa River as a condition of its consent. These reports were due by December 2015 and Mr Wright said they had expected the reports to be submitted within the timeframes.
Fish surveys and water quality testing have been, or are in the process of being, done by Affco. As yet, no results have been received.
"Agreement on sampling methodology has caused some delays. Our ultimate aim is to have all resource consents operated in the required manner and we work with consent holders to achieve this. Enforcement action is likely to be taken when all avenues are exhausted or the consent holder fails to co-operate or take positive action to remedy any breaches."
Affco declined to make comment.
In regard to Wairoa District Council, Mr Wright said the COD and suspended solids standards would protect the environment. Elevated suspended solids in the discharge occurred when the wastewater treatment plant became overloaded by stormwater leaking into the town's sewer network.
"It is expected investigations and work to progressively reduce this leakage will fix a number of issues for the sewer network and discharge over the next several years. While the current river and ocean discharge will be an option, alternatives will need to be considered, including land application."
WDC engineering manager Jamie Cox said the major issue was stormwater getting into the sewer network during heavy rain and high river levels.
"An investigation found some sewer pipe joints and junctions had ruptured, allowing groundwater from the surrounding sand layer to get into the sewer.
It has been estimated it would cost $12 million to replace the sewer network with new pipes.
Operational improvements included limiting the lower pond level so as not to be below a level which would allow potential carry-over of algae into the effluent discharge. Another improvement was the installation of a new $85,000 pre-treatment screen which increased efficiency by removing all particles greater than 6mm.
Mr Wright said Silver Fern Farms' discharge was required to meet standards based on recreational standards and for the protection of in-stream values.
In the past three years there has been one exceedance for one of the discharge standards and several volume exceedances, typically during rain.
"Their discharge is treated biologically via a four-stage treatment pond system. Monthly testing of the discharge is required.
"A survey is also completed once every two years during low-flow conditions to confirm the discharge, after reasonable mixing, meets water quality guidelines.
Silver Fern Farms communications manager Justin Courtney said their plant works and structures had been assessed by the regional council as being well-constructed and maintained.
"Stormwater during a particularly high rainfall event in January this year meant we exceeded the daily discharge limits, though it did not impact the correct functioning of the treatment in the pond. In these extreme weather event cases, the stormwater dilutes the treated wastewater, improving its quality. Normal processing flows have not exceeded our daily wastewater discharge.
"We have carried out maintenance on the final pond to increase our pond capacity."
No significant upgrades were planned for the plant at this stage. A Hawke's Bay Regional Council five-yearly report found the Wairoa River suitability for recreation was "very poor". The Gisborne Herald