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June, 2001
Controlling Runoff from Confined Livestock Areas
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| Manitoba is very fortunate to have an ample supply of
good-quality surface water. Many communities rely upon surface water for their drinking
water supply, as well as for recreational purposes such as swimming and boating.
Agricultural uses include watering livestock, irrigating crops and processing food. And,
equally important, water is used by wildlife and is home to many aquatic organisms.
However, often these same users cause surface water quality problems. Several agricultural
practices can harm surface water quality. Allowing contaminated runoff to flow into
surface watercourses is one of them. |
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What is a "confined livestock area"?
A confined livestock area, as defined by the Livestock Manure and Mortalities
Management Regulation, is "an outdoor, non-grazing area where livestock are confined
by means of fences or other structures, or topography, and includes a feedlot, paddock,
corral, exercise year and holding area." |
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Why worry about runoff?
Runoff from a confined livestock area could harm water quality if it is allowed to
enter a surface watercourse. Excessive amounts of plant nutrients, such as nitrogen and
phosphorus, will increase aquatic plant growth if they enter a surface watercourse.
Nitrogen, in the form of ammonia, is toxic to aquatic life. The organic matter in runoff
acts as a "fuel" for microscopic aquatic organisms. The breakdown of this
organic material results in a reduction of the amount of dissolved oxygen, sometimes
killing fish. Sediment carried in the runoff may contribute to silting, interfering with
fish habitat by smothering spawning areas. Runoff may also contain pathogenic
(disease-causing) organisms, which if present in sufficient numbers, create a health
hazard. For these reasons, contaminated runoff must not be permitted to enter a surface
watercourse. |
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How runoff can be prevented from entering a surface watercourse
The first step in runoff control is to prevent off-site or uncontaminated runoff from
flowing into the confined livestock area. It may be necessary to construct diversion
ditches or berms to direct clean water away from the area. |
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The next step is to ensure that all livestock pens are graded, so that
the on-site runoff is channeled to a central collection or holding pond. Depending on the
site, it may be necessary to provide more than one collection basin. Recommended pen
slopes are from two to four per cent. Diagonal pen slopes are often provided to ensure
proper pen drainage, as well as adequate ditch slope. |
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The collection basin should hold at least 7.6 cm (3 in) of precipitation runoff from the
collection area. Allowing clean water from outside the facility into the confined
livestock area will mean a larger than necessary collection basin will be required.
Provide an additional 30 cm (12 in) of basin depth or freeboard for reserve capacity. The
collection basin must be emptied as soon as possible after spring snowmelt or heavy
rainfall to be ready for the next runoff. |
Larger facilities should consider using a two-stage collection basin.
The first stage is a settling basin, which allows most of the solids in the runoff to be
separated from the liquid. The settling basin should be relatively shallow, from 0.6 to
1.2 m (2 to 4 ft) deep. It should have an area of at least 2.5 per cent of the total
collection area. The second stage is then the main collection basin. |
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A runoff collection basin must be used only if it can be made leakproof. It is recommended
that runoff collection basins be constructed to the same standards as earthen manure
storage to ensure protection of the groundwater. In areas with sandy sub-soil, it will be
necessary to line the collection basin with a clay or plastic liner.
The most practical method of runoff disposal at this time is to spread it onto
cropland. The crops will use the water and plant nutrients in the runoff. The organic
material will add to the soil organic matter, helping to improve the soil. Any pathogenic
organisms will be destroyed: by drying out, by exposure to sunlight or by other organisms
in the soil.
A basic irrigation system should be adequate for most smaller operations. Larger
facilities, such as commercial feedlots, may wish to hire a custom applicator to dispose
of their collected runoff.
In order to prevent surface runoff, the rate of application should not exceed the rate
of soil infiltration. In addition, the application rate must not exceed the annual crop
fertilizer needs. On average, runoff from confined livestock areas contains 0.4 per cent
nitrogen and 0.1 per cent phosphorus. In all cases, it is important to prevent
contaminated runoff from entering any surface watercourse when spreading it onto cropland.
Other methods of runoff disposal
Work is under way in Ontario to evaluate the use of vegetated filter strips
(VFS) as a way to safely dispose of runoff from confined livestock areas and solid manure
storages. The investigators define a VFS as "a system in which a vegetative area is
used for treating runoff by infiltration, dilution, filtration and absorption of
pollutants." The size of the VFS depends on the volume of runoff to be treated. The
vegetated area should be sloped from 0.5 to 4 per cent. Widths start at 9.1 m (30 ft),
with lengths from 91.4 m to 274.3 m (300 to 400 ft). Crops grown in the treatment area
must tolerate both wet and dry conditions – examples are reed canary grass, brome
grass and orchard grass. Vegetated filter strips have not been evaluated under Manitoba
conditions, so producers considering using a VFS to dispose of runoff from a confined
livestock area are encouraged to "do their homework" before establishing a
vegetated filter strip. |
Another way of treating contaminated runoff being investigated in Manitoba is to use constructed wetlands. It has long been known that natural
wetlands have the ability, by way of both physical and biological processes, to filter and
cleanse contaminated water. A constructed wetland is a man-made wetland buillt to treat
contaminated effluent, such as waste water and storm water runoff. Two wetlands were
constructed in 1996 and 1997 in Manitoba to test their effectiveness in treating runoff
from beef cattle operations. It is still too early to provide results of these projects or
make recommendations about constructed wetlands. As with vegetated filter strips,
producers interested in setting up constructed wetlands to treat runoff from their
operations should obtain technical advice before beginning construction. |
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Runoff Control Information
Farm Practices
Guidelines for Beef Producers in Manitoba
(available from Manitoba Agriculture, Food and Rural Initiatives)
Farm Practices
Guidelines for Dairy Producers in Manitoba
(available from Manitoba Agriculture, Food and Rural Initiatives)
Consulting Engineering Firms
(Look in the Yellow Pages under Engineers – Consulting.)
The Manitoba Clean Water Guide
(available from Manitoba Environment)
Keep a Clean Image: Livestock and Water
(available from Alberta Agriculture)
Protecting Your Shorelands for Better Farming and Ranching, and
Healthier Fish Habitat
(available from Fisheries and Oceans Canada)
Troubled Waters: Threats to Fish Habitat in the Prairie Provinces
(available from Fisheries and Oceans Canada)
Evaluation of Vegetated Filter Strips (VFS) to Treat Beef Feedlot
and Dairy Yard Runoff in Ontario
(Canadian Society of Agricultural Engineering paper 97-500, available from
Bioresource Engineering Dept., University of Saskatchewan, Saskatoon)
Manitoba Agriculture, Food and Rural Initiatives Regional Engineers
Beausejour |
(204) 268-6011 |
| Brandon |
(204) 726-6408 |
| Dauphin |
(204) 622-2020 |
| Portage la Prairie |
(204) 239-3364 |
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