There is no evidence of long-term environmental impacts from January's Albert River sewage spill, with the waterway recovering to normal levels in all key areas, an independent environmental study has found.
Griffith University (GU) was engaged by City of Gold Coast to undertake an environmental impact assessment focusing on oxygen levels, nutrient concentration, accumulation of metals and PFAS levels during and after the event.
City of Gold Coast Acting CEO Alisha Swain said the City received the final summary conclusions from GU today and was relieved they indicated that the Albert River had recovered quickly.
"The advice we received at the time was that the significant flows were likely to have diluted the spill, delaying its detection and also lessening environmental impacts. It is a relief this is the case." Ms Swain said.
"However, we know the low dissolved oxygen in the river as a result of the spill would have impacted immobile animals in the local vicinity.
"We also know that there was a significant failure in our systems and we remain focused on implementing recommendations from the earlier independent investigation which we released to the public.
"The City is committed to rigorous and continual improvement across all areas and committed to applying lessons learnt to prevent future incidents," Ms Swain said.
Ms Swain said the City would continue to closely monitor the river and had already undertaken audits of the key infrastructure in the northern Gold Coast.
"We continue to cooperate with the State Government investigation into the spill and will continue to share all updates with our community via our website."
Key findings were:
- Dissolved oxygen saturation levels were extremely low during the event but have recovered quickly to normal levels. It is likely immobile animals like molluscs were impacted. Fish would have moved away.
- Nutrient levels spiked but did not result in algal blooms. Levels have returned to normal.
- Nitrogen levels are normal.
- Metals found in the sediment were most likely due to long term accumulation, not the spill.
- The spill contained low concentration of PFAS chemicals and after dilution would have posed a low risk to the environment.
- Shore crabs collected from the lower Albert had higher levels of manganese. This is not conclusively linked to the spill due to multiple sources of contaminants in the Albert catchment, however the low oxygen because of the spill may have increased the bioavailability of manganese.
Last month the independent investigation determined that the break which was detected in April was due to corrosion most likely caused by "aggressive" soil or groundwater, and the omission of a specified wrapping for the pipe at the time of installation (2005) was also a contributing factor.
It also found that condition assessments of the main and a proposed project that would have reduced flows and enabled pipeline renewal had been deferred.
The GU environmental impact conclusions can be found here.
