Revision Criterion 2.6 – Water Quality 

Eutrophication, the excessive richness of nutrients in a body of water, is one of humanity’s most serious environmental problems. It occurs when the environment becomes enriched with nutrients, increasing the amount of plant and algae growth, which can reduce dissolved oxygen in waterbodies. This can impact fish stock levels of sensitive species with cascading effects on entire aquatic ecosystems and overall loss of biodiversity. The general deterioration of water quality may also hinder water use by other communities and industries. 

A new Water Quality proposal 

The ASC’s species-specific standards contain requirements on water quality. However, they:

• Vary considerably in language and approach – even when the standards cover similar production systems.
• Focus predominantly on individual farm sites without considering the impacts of other farms that are located in the same waterbodies, therefore lacking an area-based approach. 

Due to the issues mentioned above, ASC is revising the Water Quality requirements as part of the ASC Farm Standard development.  The revision is carried out with support from an expert Technical Working Group (TWG). The new water quality proposal deviates from an approach based only on prescribed requirements linked to an individual farm site, which might have limited or insignificant impacts on water quality and moves to an approach based on risk, in which the cumulative effect of multiple users is considered. 

Taking into account the cumulative nature of eutrophication, the new water quality proposal categorises receiving waters according to their nutrient retention capacity based on hydraulic residence time, differentiating between still/slower flowing and faster flowing systems. In this context, the indicators within the proposal have been developed to identify the nutrient retention capacity of the receiving waterbody and the susceptibility of at-risk waterbodies to additional nutrient inputs. Farms located in the most sensitive waterbody type must form an Area Management Agreement (AMA). If changes in trophic status start occurring, farms will need to assess the contribution of aquaculture to nutrient inputs and implement corrective actions as part of the AMA. These actions will reduce the rate of change in tropic status and prevent the eutrophication of a waterbody. 

ASC believes that the proposal successfully achieves the aim of developing a method for water quality management that focuses strongly on cumulative impacts and the carrying capacity of a waterbody. This will strengthen the position of ASC farms when addressing water quality impacts.  

More information

• ASC launches Stakeholder Consultation on two major criteria of the ASC Farm Standard and Pike-perch Module

[Page last updated on 01.03.2023]