Water Quality

Agriculture

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Agriculture

Agricultural operations, if not properly managed, can discharge a wide range of contaminants, including those from manure, fertilizers, pesticides, and eroded soil particles. The most worrisome contaminants are ammonia, nutrients, pathogens, and sediments. Ammonia is toxic to fish, while nutrients can impair water quality, as in the Serpentine and Nikomekl rivers and the Abbotsford aquifer. Manure is a significant source of nitrogen, phosphorus, biochemical oxygen demand, and waterborne diseases. Proper management is required to avoid adverse effects to water supplies and human health. Environmentally sound use of manure from farms is a constant challenge in the agricultural industry, and is not unique to British Columbia. In some parts of the Fraser Valley, nutrients from manure, combined with inorganic fertilizer use, exceed the capacity of local lands to assimilate the available nutrients. In some areas, the excess is between 300 and 400 kilograms of nitrogen per cropped hectare. When too much manure and chemical fertilizer are spread onto fields for crop enhancement, excess nitrogen leaches into ground water or enters

adjacent streams. Timing of manure spreading and other management practices can affect the severity of the impact. If spread in the late fall and early winter, when the plants' nutritional needs are the lowest, winter precipitation can carry ammonia, pathogens, and oxygen-demanding materials into waterbodies.

Pesticides can contaminate waterbodies by several routes, including spillage, improper storage, application too near or into ditches and streams, leaching from soils, or washed away in runoff. About $22 million per year is spent on application of 120 different types of pesticides in British Columbia. The area of provincial agricultural cropland treated with pesticides increased from about 425,000 hectares in 1971 to about 550,000 hectares in 1986 - about a 30% increase. On Crown land, the use of pesticides has stabilized or decreased in the last few years, suggesting that the promotion of integrated pest management in British Columbia since the 1980's may be paying off.

There is little information about the degree of pesticide contamination of water in the province. However, an assessment of the Lower Mainland's Abbotsford-Sumas aquifer, which provides drinking water to nearly 100,000 people, found only traces of 16 pesticides in the aquifer. Some of the pesticides detected are either no longer used or their use is restricted. The levels of pesticide were well below current drinking water guidelines and do not pose an imminent threat to human health. A comprehensive inter-ministry ground water quality assessment (Fraser Valley Groundwater Monitoring Project) conducted in 1993/94 indicated ground water quality in the Fraser Valley was generally good, except for elevated concentrations of nitrate-nitrogen in the Abbotsford, Hopington, and Brookswood aquifers.

 

Solutions

The information in the following sections is taken from the document Watershed Stewardship: A Guide for Agriculture and should be referred to for further information. For details applicable to specific agricultural sectors refer to the following Ministry of Agriculture, Food and Fisheries publications:

• Environmental Guidelines for Beef Producers
• Environmental Guidelines for Berry Producers
• Environmental Guidelines for Dairy Producers
• Environmental Guidelines for Field Vegetable Producers
• Environmental Guidelines for Greenhouse Growers
• Environmental Guidelines for Horse Owners
• Environmental Guidelines for Mushroom Producers
• Environmental Guidelines for Nursery and Turf Producers
• Environmental Guidelines for Tree Fruit and Grape Producers
  

Site Planning
Proper site planning can help prevent or reverse damage to fish and wildlife habitat and water quality. It can also make farming your land more financially and personally rewarding.

Farms and other agricultural operations should have a management plan to help identify issues before they become problems. A well thought out plan can also help secure financing from financial institutions that are beginning to request environmental assessments to accompany loan applications.

Your farm plan should document information about the physical attributes of the farm including native vegetation, wetlands, watercourses and other natural habitats. The plan should also include information about the topography of the land, soil types, lands marginal for farming and climatic conditions. This information can be used to evaluate prime production areas, identify natural areas to remain and those requiring remediation. The site plan will also be useful when considering improvements to existing facilities, or new buildings and storage areas.

For more detail on preparing a farm plan refer to Watershed Stewardship: A Guide for Agriculture.

The detention pond on the left collects runoff from a dairy farm. The runoff is further treated in the constructed wetland on the right before being discharged.

Livestock Management

Grazing patterns, livestock numbers and distribution, and manure management all have implications for soils, water quality and fish and wildlife habitat. Small changes in your operation can have major benefits for your farm, for streams and wetlands and for others downstream from you in the watershed. When managing livestock handling and feeding areas, be sure all provisions of the Code of Agricultural Practice For Waste Management

are met. Provide off-stream livestock waterers whenever possible. Where access to natural watercourses is needed, it should be restricted to locations where developed access has been established.

Restricted livestock access to a natural watercourse

Waste Management
The proper management of waste products prevents pollution of water, soil and air. Producers are responsible for ensuring that the environment is protected from contamination by agricultural wastes.

Land application of manure can help increase crop productivity but when improperly applied, applied in excess of crop uptake or improperly stored can be very damaging to the environment. Human health risks are a concern because of pathogens and nutrients (nitrates) which can contaminate drinking water. Water which is contaminated will also be unpalatable to livestock. Excess nutrients can also have an impact on water quality and fish habitat, causing excess algal and plant growth, and decreasing dissolved oxygen levels. Manure runoff also contains high levels of ammonia which is toxic to fish.

The key to good manure management is a nutrient management plan which addresses the following:

Appropriate Manure Storage

• construct manure storage facilities to prevent escape of manure or manure leachate to surface and ground water;
• ensure the capacity is large enough to store manure until it can be effectively used as fertilizer;
• allow capacity for storing contaminated runoff from livestock handling areas, as well as rainfall and milking center wastes if needed;
• cover manure storage areas to maximize capacity — you won't need such a large facility if it is not collecting rainwater;
• locate storage areas well back from watercourses and water supplies — 30 m minimum from any source of domestic water and 15 m minimum from any watercourse or lake. Greater distances are preferred;
• if storing liquid manure, secondary containment (such as a berm) is suggested for storage facilities which are near a watercourse or lake.
  

Manure Application

Manure applications must be planned and timed so that:

• the amount and timing of nutrient applications match soil conditions and optimize crop uptake;
• there is no runoff or excessive leaching to any body of water. Avoid applications during seasons of intense rainfall and do not apply manure to snow, frozen ground or saturated soils;
• manure should not be applied within the 15 m riparian leave area or any permanently wetted waterbody.
  

Excess Manure

If the amount of nutrients in the manure generated on your farm exceeds what you can appropriately use as a fertilizer:

• investigate the carefully balanced feeds which enhance nutrient uptake by livestock and reduce the nutrient levels in the manure;
• arrange for appropriate off-farm disposal (i.e., composting and selling or finding another user) of any remaining excesses.
  
  

Other wastes, including milking parlor wastes, woodwaste, dead animals and pesticides must also be handled in a manner that minimizes the impact on the environment. Refer to the Watershed Stewardship: A Guide for Agriculture for more information.

Manure storage area at a dairy farm

Soil Management and Conservation
Conserving soil is fundamental to productive agriculture. Soils develop slowly, but can be easily harmed by human activity, causing decreased crop production, higher management costs and impacts on the aquatic environment. Many steps taken to protect soils can also benefit water quality and fish habitat.

Pest Management
Pesticides can provide benefits to producers and consumers alike, but can also have negative effects if they enter ground water or surface waterways. Many producers have adopted sophisticated integrated pest management (IPM) techniques which help reduce the overall use of pesticides while maintaining farm profitabilitiy.

Integrated pest management uses a combination of the following methods to control pests:

• cultural (e.g., crop rotation which reduces impacts from crop-specific pests, and companion crops which can be used to out-compete weeds between crop rows);
• physical (e.g., stick traps);
• chemical (e.g., pheromones, biocides); and
• biological (e.g., predator insects).

 

Resources and Links

Watershed Stewardship: A Guide for Agriculture. 1997. The Stewardship Series. Province of British Columbia and Department of Fisheries and Oceans.

Agricultural Waste Control Regulation.

Animal Waste and the Environment. University of Georgia College of Agricultural and Environmental Sciences.

Management Measures for Agricultural Sources. US Environmental Protection Agency.

Hog Watch.

Buchanan, B. Agricultural impacts on water quality in Alberta. Alberta Agriculture, Food and Rural Development.

Unified National Strategy for Animal Feeding Operations. US Department of Agriculture and US Environmental Protection Agency.

Agriculture and the Environment. National Resources Conservation Service, US Department of Agriculture.

National Agriculture Library. Water Quality Information Center. Agricultural Research Service, US Department of Agriculture.

Cows and Fish: Alberta Riparian Habitat Management Program.

 

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