■ Fertilizers and pesticides from residential and agricultural runoff (e.g.,
feedlots, golf courses, lawns, etc.)
■ Discharge from water treatment facilities that do not have the capacity to
handle nutrient and biodegradable waste discharge
■ Use of household products that contain phosphates (e.g., detergents)
■ Sewer and drainage overflows that can occur when the rainfall amount
exceeds the wastewater treatment capacitySteps for Controlling Cultural Eutrophication
■ Planting vegetation (buffer zones) along streambeds, which slows erosion
and absorbs some of the excess nutrients
■ Constructing wastewater lagoons and retention ponds near agricultural
areas
■ Controlling the application and timing of applying fertilizer
■ Controlling runoff from feedlots
■ Updating building codes to utilize permeable pavement to absorb the
excess urban runoff
■ Using monetary and tax incentives to convert existing watering systems to
drip irrigation and to replace landscaping with native vegetation that is
less water-demanding
■ Upgrading existing water treatment plants to better control nitrate and
phosphate pollution through tertiary standards and other advanced
technologiesBIODEGRADABLE WASTES
The release of biodegradable wastes into receiving waters is also a major
component of cultural eutrophication. These wastes are used by bacteria and
other microorganisms and can cause oxygen depletion (hypoxia) in the water,
resulting in an increase in anaerobic bacteria that can produce ammonia, amines,
sulfides, and methane. The result is “dead zones.” Most dead zones occur in
bottom, and near bottom, water near inhabited coastlines, where aquatic life is
most concentrated. Major dead zones include the northern Gulf of Mexico region
surrounding the outfall of the Mississippi River, areas of the Chesapeake Bay,
and the coastal regions of the Pacific Northwest.