Animal waste contains a high concentration of nutrients as well as pathogens and bacteria.
One of the most common fertilizers used by gardeners is composted horse and cow manure. A number of water-borne diseases including tuberculosis and salmonella can be transmitted to humans by microorganisms in animal feces. Bacteria levels in stormwater appear to be greater in urban and suburban areas than in commercial or industrial zones. One cause may be the high concentration of pets associated with residential areas. Frequently pets are walked along roadways or near waterways, areas where animal waste can quickly find its way into nearby lakes and streams.