How Livestock Affect Our Water
When it rains, water that does not evaporate or soak into the soil runs downhill, eventually draining into a stream, lake, or wetland. This water, or “runoff,” picks up the pollutants in its path as it travels. If this water happens to be traveling across a poorly managed horse property, it’s likely to pick up nutrients and sediments from exposed soil and manure. Pollutants on the ground can also soak through the soil and pollute groundwater. Listed below are some potential pollutants typically found at a horse place:

Nutrients
There’s no question that the nutrients in manure are great for plants. This is a good thing in a garden or on pastures, but the same nutrients that help plants grow on land also encourage the growth of algae and other aquatic weeds in water. As these weeds grow, they can shade out and kill other aquatic vegetation beneath the water’s surface. As aquatic plants and algae decompose, they create unpleasant odors and surface scum and use up the oxygen in the water that fish and other aquatic life need. Salmon and trout are particularly at risk because they need high levels of oxygen to live.

Nitrate
Nitrate in manure can be harmful to humans when consumed at high levels. When nitrate soaks down through the soil, it can end up contaminating groundwater. Groundwater is the source of drinking water for many people, especially those in rural areas. Excessive amounts of nitrate in drinking water can cause health problems such as blue baby syndrome and may be linked to cancer and birth defects. Recent samplings of wells in northern Whatcom County have found nitrate levels above the U.S. Environmental Protection Agency’s safe drinking water standards.

Sediment
Most people realize that rainwater plus exposed soils equals mud. What many people don’t realize, however, is that this combination can also lead to water pollution. Sediment (often originating as topsoil, sand, and clay) may seem harmless enough, but it poses serious problems in the water. Excess sediment turns stream and lake water cloudy, making it less suitable for fish and other aquatic life as well as for recreation. Sediment can be especially harmful in fish-bearing streams where it can smother trout and salmon eggs, destroy habitat for insects (a food source for fish), and cover prime spawning areas.

Bacteria
Animal manure may contain bacteria, viruses, and parasites that can contaminate nearby drinking water sources. High bacteria levels in the water can cause gastrointestinal disorders and other medical problems for swimmers. Fecal coliform bacteria are found in the feces of warm-blooded animals, including humans.

Fecal coliform bacteria levels are commonly measured to identify possible contamination of water from human or animal waste. The coliform bacteria may not necessarily produce disease, but can indicate the presence of other bacteria, which may cause infections, hepatitis, typhoid fever and other illnesses. High levels coliform bacteria found in the water around shellfish growing areas can lead to shellfish bed closures.

Because of bacterial contamination (fecal coliform), the Washington State Department of Health closed shellfish beds in both Drayton Harbor and Portage Bay in the mid and late 1990s. These Whatcom County shellfish growing areas are still closed to shellfish harvesting because unsafe levels of bacteria have been found.

Our guide to environmentally friendly horse-keeping covers manure and pasture management options for small farms that will not only make life better for you and your horses (and/or other livestock), but will also make your farm more productive. The manual revolves around horses, but the management techniques and environmental principles are applicable to keeping all livestock, including alpacas, sheep, beef cows, etc…

Download our Guide to Environmentally Friendly Horse Keeping (Adobe pdf, 1.5MB)