Water Quality Requirements for Saskatchewan's Agri-Food Industry : Executive Summary

This report summarizes water quality requirements for the agricultural sector in Saskatchewan, by grouping similar areas together. The following is a list of the different groups that were included:

• Livestock - water quality requirements
• Irrigation - water quality requirements
• Micro-irrigation for horticultural applications - water quality requirements
• Chemical mixing - water quality requirements
• Industrial processing of agricultural products - water quality requirements
• Domestic uses - water quality requirements

The unique aspects of each of these groups have been addressed. The information was collected primarily from extension materials, text books and Internet sources. This work was not designed to be a critical evaluation of water quality requirements but rather was intended to assemble easily accessible information from various sources with particular attention to agricultural extension agencies. Emerging issues within the different groups were explored further under the heading "Emerging issues for the agriculture sector - water quality requirements".

The U.S. National Research Council's (1974) recommendations, together with other reports (especially the Canadian and Australian Water Quality Guidelines for Livestock) have been used to produce a list of concentrations of substances that should preferably not be exceeded for consumptive livestock water uses. Livestock industry water quality problems can be both of a health concern and of a delivery concern, where restricted flow nozzles may clog because of microbial growth, chemical precipitation or particle trapping. However, for an industrial sector with such large investments as the North American livestock industry, it is disconcerting that so little has been done to summarize the knowledge in this field, as most extension agencies refer to material that is more than 20 years old. There is no consensus as to what level of microbial contamination is acceptable in livestock water supplies; nor is there conclusive information on effects of poor quality water on livestock performance. The present options when dealing with water quality problems are quite limited. For example, producers facing microbial problems can disinfect and/or filter the water and excess sodium in the water can be offset by adjusting the sodium level in the feed. There is a need to provide better information in a comprehensive fashion so that livestock producers can optimize their operations.

Irrigation was divided into two sections: standard irrigation (center pivot, large nozzle type systems) and micro-irrigation (trickle and drip irrigation mainly using low volume, small nozzle type systems). For micro-irrigation, water quality concerns include effects on plants as well as nozzle (emitter) clogging problems. Standard irrigation is largely concerned with effects of water quality on plants. Water quality effects on plants include total soluble salt content (salinity hazard), relative proportion of sodium cations and other cations (sodium hazard-soil permeability effects), alkalinity effects (carbonate, bicarbonate, calcium and magnesium concentrations), concentration of toxic elements (sodium, chloride and boron in particular), excessive nutrients (yield and quality problems), unsightly deposits (reduced marketability), and excessive corrosion of equipment. When dealing with effluent irrigation, some additional criteria must be addressed. Effluent suitability depends on the concentration of compounds that may become toxic, such as sodium, boron, nickel, cadmium. In addition, there is potential for nutrients to accumulate in the soil. This area has been extensively researched, although it appears that nutrient/toxic effects of different compounds (for example boron) may require assessment on a species-specific basis. Most Saskatchewan surface water sources are suitable for centre-pivot irrigation, but many groundwater supplies are too saline for this purpose.

The water required for micro-irrigation applications (most horticultural applications fall under this category) must be of a considerably higher quality than what is required for standard irrigation applications (centre pivot systems). In micro-irrigation applications, the small size of the nozzles (emitters) facilitates precipitation of chemicals, trapping of particles, or growth of organisms in the orifices. Therefore, clogging of nozzles is a major concern to micro-irrigation applications. Many characteristics of both surface and ground water in Saskatchewan increase the probability of plugging; both inorganic and organic compounds can cause clogging, and thus must be removed. Optimum nutrition is also essential in the production of most horticultural crops, as plant quality is a key selling point for Saskatchewan-made products. Reverse osmosis is generally recommended only as a last resort for water treatment; when such expensive treatment technologies are used, there is a great need for pre-treatment of the water. Research and development into pre-treatment of micro-irrigation water is called for. More inexpensive treatment techniques could minimize the need for reverse osmosis treatment. There is also a need to study membrane processes. Ensuring that the most suitable membranes are used for water treatment would be of benefit.

The quality of the water used as a carrier for pesticides (i.e., chemical mixing) can affect the efficacy of the pesticides. Specific ions (Ca, Mg) will decrease performance of a number of pesticides including glyphosate and 2,4-D amine. NaHCO3 may also decrease the effectiveness of several pesticides including tralkoxydim, sethoxydim, and clethodim (Achieve, Poast, Select) and 2,4-D. Liquid ammonium sulphate fertilizer (and some other nitrogen fertilizers, such as urea can alleviate some of the negative effects of Ca, Mg, and NaHCO3 on pesticide efficacy. High pH levels can inactivate some pesticides (organophosphate compounds). No work has been done to systematically show the decreased effects of these various pesticides when they are used with natural water sources high in inorganic and organic material. Saskatchewan surface and ground waters commonly contain high levels of dissolved organic matter, which may also modify the efficacy of pesticides. To better determine the effects of dilution water on pesticide efficacy, it will be necessary to use improved evaluation methods that can measure such differences in addition to traditional visual efficacy studies in the field. If efficacy is increased by using water of suitable quality then crop protection will be improved possibly to the extent that less pesticide could be applied. Increased chemical optimization with reduced doses would also result in environmental benefits and a more competitive farming product.

Food and non-food processing industries have a wide scope of acceptable water quality requirements, which range from poor water to ultra-pure water. Industries that produce water for consumption (breweries, soft drinks, and bottled water) require high quality water with specific characteristics. For example, in the manufacture of beer, precipitation of bicarbonates can occur when phosphate-rich malt is used. Taste, odour and colour must also be controlled. In order to locate food and non-food processing industries in rural Saskatchewan, existing municipally treated water will likely require polishing treatment, including removal of fouling compounds (particulate and dissolved organics), scaling compounds (calcium, magnesium, silicates and carbonates), and some other compounds (such as iron and manganese). The issue of microorganism removal from the water has not yet become critical, although it is anticipated that this will occur during the next several years. Water requirements of the food and non-food processing industries are intimately linked with effluent disposal. In some jurisdictions, processors must pay close attention to the amount of effluents produced (quantity of both water and organic load); attention to these details can reduce costs and it can dramatically lower the environmental impact of effluents released. Assisting companies in evaluating effective water reduction techniques and developing water optimization strategies are essential steps in lowering industrial water requirements as well as reducing effluent releases.

Guidelines (not covered by law) and standards (enshrined in law) are used to guide water users and consumers on the suitability of distributed water for human consumption. Both the U.S. and Europe have drinking water quality standards, while Canada and Saskatchewan have only guidelines. In addition, the European and U.S. standards are often more stringent than the Canadian guidelines, which are based on negotiations between federal and provincial agencies. In most developed countries, federal agencies are ultimately responsible for the provision of safe drinking water (for example the U.S.). In Europe, all countries must abide by European Community Standards, which makes drinking water quality uniform across many countries. In contrast, Canada has taken the opposite approach. In Canada, the provision of safe drinking water rests with provincial agencies. Federal agencies can only give advice. Even provinces with small population bases, such as Saskatchewan, are therefore expected to maintain expertise capable of dealing with complicated drinking water issues. When such expertise is in short supply, the public will suffer. In "Domestic uses - water quality requirements", different guidelines and standards have been summarized and a comparison is made between European and U.S. standards vs. Canadian guidelines.

A large number of Saskatchewan untreated ground water and surface water sources exceed standards/guidelines for many compounds. It is essential to support research and development that will provide effective and sustainable treatment solutions for poor quality ground and surface water so that it can become palatable and safe. In order to address these issues in a systematic fashion, it is necessary to evaluate different treatment techniques for their suitability to solve specific water quality issues that are of concern in Saskatchewan.

The emerging issues for the agricultural sector include removal of particles, inorganic ions, fouling components, microbes and microbial by-products. The processes required to remove problem compounds and microorganisms must be established. Saskatchewan surface and ground waters contain problem compounds for most water uses, but linkages between water quality and impairment of process or product have often not been established. The reason for this has, in some instances, been due to the use of experimental techniques that are not sufficiently sensitive to adequately define the problems.

For more information contact: Water Quality Unit