Revision Criterion 2.7 – 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 water bodies. 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 may operate on the same water bodies, 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 effects on a water body and moves to an approach based on risk in which the cumulative effect of multiple users is considered.

Considering 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 (‘lentic’) and faster flowing (‘lotic’) systems. In this context, the indicators within the proposal have been developed to identify the nutrient retention capacity of the receiving water body and the susceptibility of at-risk water bodies to additional nutrient inputs. Where relevant, further assimilative capacity assessment and coordinated area management agreements and actions are required to reduce the rate of change in the tropic status and prevent the eutrophication of a water body.

The proposal requires farms to monitor water quality to prevent eutrophication by identifying when a water body shows signs of upward trophic status changes. When this is identified for lentic systems or water bodies with a still or slow flow, the proposal requires farms in that at-risk water body to participate in an Area Management Agreement (AMA) to monitor, prevent and mitigate eutrophication impacts collectively. If farms do not participate or do not reach an agreement, farms located in that water body will not comply with the proposed requirement.

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 water body. 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]