Cocktail of chemical hazards found in Hearnes Lake

Water sampling on tributaries leading into Hearnes Lake has detected a cocktail of agricultural chemicals during rainfall events, including a highly-toxic insecticide, Methomyl, which may present a hazard to humans and animals. 

The levels detected are in excess of six times the recommended Australia and New Zealand Environment and Conservation Council (ANZECC) guidelines. Water quality expert and project coordinator, Maxine Rowley, warns that the community should be aware of the risks, and suggests that the waters of the lake should be avoided until it is established the contamination is no longer occurring.

The water-testing program, funded by a Council Environmental Levy grant, and supported by the Sandy Beach Action Group (Sandbag), involved a three-stage sampling process at five sites, on Double Crossing Creek, and Houp Gully, during high rainfall events in 2021 (see map). Testing was done by members of the Hearnes Lake Catchment Management Group. The full results of the research are yet to be released, and are being forward to the EPA and Council, with a request for follow-up action. 

Chemicals detected included the fungicide Benomyl, banned in Australia since 2006.

Eleven other farm chemical residues were found. However, the highest concentrations were for Methomyl, (below) at 22.8 micrograms per litre, found at a sample site in Houp Gully, off Condons Road, in April, and it was again detected in September. 

It is the first time that Methomyl has been detected in Hearnes Lake, however, the toxicity of the chemical to aquatic and terrestrial species is well known. It is used as a fly bait under various commercial product names. A review article in the science journal Molecules (February 2020) states that Methomyl has been banned in many European countries due to its extremely high residual toxicity.

Prolonged exposure affected neural, muscular, genital, intestinal, and reproductive functions.  Its residues could affect non-target organisms, through the food chain, and it had a half-life of more than 30 weeks in air and water.

The water sampling results follow on from a fish kill in Hearnes Lake in 2018 linked to the agricultural chemical and nerve toxin Chlorpyrifos. Extensive research, conducted by Southern Cross University, has shown that agricultural pollution from fertilizer in Hearnes Lake ranks as among the worst in the world, with nitrogen oxide levels at 100 times the ANZECC trigger value. Also, sediment sampling by SCU detected levels of arsenic that exceeded ANZECC guidelines, and showed, more broadly, that the rise in heavy metals in the estuarine system coincided with the emergence of blueberry farming. 

Chemical pollution from agricultural runoff has become a major environmental concern across the entire mid-coast, and particularly around Sandy Beach and Woolgoolga where there has been the rampant spread of blueberry farms. Across the region, spray drift is also a major issue, and the EPA has noted that this makes up 76 percent of its complaints. In recent years, Council surveys detected pesticides in fourteen percent of water tanks, including traces of the banned substance Eldrin, a persistent organic pollutant, banned since 1987. 

The chemical pollution in Hearnes Lake is one of several environmental hazards associated with the rise of intensive horticultural operations. Problems of dieback in the mangroves and high nutrient levels in the water, have been linked with the poor irrigation practices and the widespread violation of water rights. Leaders in the blueberry industry usually lay the blame on rogue operators, however, the enormous economic and political power of the industry has created a lax regulatory environment. 

Hearnes Lake meets the coast near the Solitary Islands Marine National Park

No obligation exists for pesticide users to notify neighbours of ground spraying, and this includes schools, private dwellings and care facilities.

Calls for tighter regulation, and stricter controls, such as the need for Development Applications, to enforce buffer zones and to limit the extent of operations have been steadfastly ignored by policymakers. 

A submission last year to the Coffs Harbour Local Growth Management Strategy, by the Intensive Plant Agriculture Watch group and Sandbag noted that the environmental problems, associated with the heavy reliance on blueberry farming, were having long-term environmental and economic consequences. It was undermining the diversity of the local farm economy, reducing the region’s ability to be self-reliant, and would limit the scope of promoting the region as a clean green ‘Eco’ destination. 

Submission author, Sandbag president, Dr Peter Quiddington, argues the heavy concentration of the blueberry industry presented a ‘wicked paradox’. The economic indices all point to a long-term advantage in carefully managing the region’s natural assets. However, the largest rural industry had a reputation for polluting the environment, violating water rights, and creating potential health hazards. 

“In spite of what may be the best intentions of many growers, blueberry production on an industrial scale, in close proximity to residential areas, without strict regulation, is quite demonstrably not conducive to the promotion of healthy living and a clean environment”, he states.

The Council, and the State government, were reluctant to bring in tighter regulation and strict enforcement. As a result, the industry continued to operate under a voluntary code of conduct, within a regulatory atmosphere where shortages of staff and resources meant monitoring and enforcement was inadequate.

He said, “legal research had shown that this situation arose because local authorities were beholden to powerful industry forces that operated on a global scale, and whose operations required a complex regulatory framework, but which local authorities lacked the skills and resources to manage”. 


The above is a joint media release, 29 November 2021, from the Hearnes Lake Catchment management Group and the Sandy Beach Action Group (SANDBAG).

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