Land Based Sustainable Aquaculture Strategy - Part 5

7/ Water considerations

Overview

The following is an overview of the issues that need to be considered when determining whether a proposed site would have a reliable water supply of the necessary quality and quantity for the success of an aquaculture business. This is not an exhaustive list but a guide only.

Water budgets for any aquaculture venture must be carefully considered. Water budgets should be calculated based on volumes required to fill tanks, pipes, ponds and storages, seepage, evaporation and operational procedures.

Water supply quantity

PREFERRED LOCATION

A site with abundant, permanent and affordable supply of good quality water with no access restrictions.

An abundant, all -seasons supply of good quality water is essential for land based aquaculture. The quantity of water required will be dependant on the size of the farm, type of farm infrastructure (pond or tank), water budget of the site (rainfall and evaporation), discharge classification (closed, semi closed or open systems) and species requirements. Water sources may include estuaries, rivers, ocean or bay, irrigation channels, bores, saline interception schemes, municipal supplies and over land catchment. All waters should be tested for compatibility with the selected species early in the planning process. Pumping costs can be high and should be minimised with options for gravity flow, low head or relatively short suction and delivery lines. These issues must be considered when evaluating a site and assessing layout options.

Potential impacts of climate change need to be factored into any water quantity and Quality investigations. The NSW Office of Water (NOW) may assist early in the planning process to ascertain water management issues affecting water availability including water harvesting or extraction from a water source. Local government approval may also be required for the construction of any water storages.

NSW Water Quality Objectives

Water quality must be of a standard that satisfies all the physiological requirements of the targeted species. Guidelines exist for acceptable parameters for some species. Sub-optimal or poor water quality can increase the running costs of operations significantly through poor growth, disease, loss of stock, equipment deterioration and expenditure on remediation.

The NSW Government is committed to ensuring the long-term health of NSW waterways, with improved water quality and flow regimes its prime objectives. The intent is to achieve a better balance in the sharing of water between users and the environment, and reduce the stress on rivers and aquifer systems.

For each of the State’s catchments, the State government has endorsed the community’s environmental values for water known as ‘Water Quality Objectives’ (WQOs). 

The NSW WQOs are consistent with the agreed national framework for assessing water quality set out in the ANZECC 2000 Guidelines. These guidelines provide an agreed framework to assess water quality in terms of whether the water is suitable for a range of environmental values. The WQOs provide environmental values for NSW waters and the ANZECC 2000 Guidelines provide the technical guidance to assess the water quality needed to protect those values.

Water quality and flow objectives are required for the protection of aquatic ecosystems; visual amenity; recreation, aquatic food, commercial shellfish production; maintaining wetland and floodplain inundation; managing groundwater for ecosystems; minimising the effects of weirs and other structures; maintaining or rehabilitating estuarine processes and habitats; and maintain natural flow variability. Particular water quality issues include:

• Nutrients and other contaminants in stormwater and sewage outflows and the release of highly acidic waters from ASS areas into estuaries;

• Dredging and drainage works within the flood planning area that could disturb ASS.

The NSW Shellfish Program administered by the NSW Food Authority regularly monitors estuarine water quality to support commercial shellfish production.

Water supply quality for aquaculture

PREFERRED LOCATION

A site having consistent high water quality and unlikely to adversely affect water quality for other users.

Access to reliable potable (drinking) water or mains water for processing, pre-market conditioning and employee uses.

Avoid sites downstream of land uses that are likely to adversely affect water quality (eg. downstream of sewage treatment works discharge, town storm-water overflows, industrial centres, proximity to agricultural chemical uses or recreational boating including marinas).

In evaluating the suitability of the quality of a water supply, factors that need to be considered include:

• the water is free of organic, agricultural or industrial pollution (pesticides, heavy metals);

• the water is free of suspended particles (check particulates - composition (organic and inorganic), size, concentration, likely seasonal variation);

• the waters physical and chemical properties (pH, salinity and tidal amplitudes, temperature, dissolved oxygen, ammonia, nitrite and nitrates, alkalinity and hardness, hydrogen sulphides, chlorine, turbidity, carbon dioxide, etc);

• the water is free of pathogens, trash fish and other undesirable aquatic organisms.

It is desirable that the source of water for aquaculture meets the relevant criteria set down in the ANZECC Water Quality Guidelines including protection of aquatic ecosystems and aquaculture and human consumption of aquatic foods. The guidelines suggest levels of physio-chemical parameters that would be required to maintain a viable natural aquatic community and provide guidance relating to levels of organic contaminants that may cause tainting of the products.

If the water supply does not meet the criteria set out in the ANZECC Guidelines, you need to assess the potential effect this would have on the selected species at all stages of the life cycle (eg. an animal may tolerate waters having a pH of 6.0, however, eggs and larvae may not survive).

In some waterways, the water quality may meet the criteria for protection of the aquatic communities, but not meet the guidelines for human health or food safety requirements. See ANZECC Guidelines and consult NSW Food Authority.