Glossary

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agricultural nonpoint source pollutants

Nonpoint sources enter a water body in a diffuse manner with no definite point of entry, and where the source is not readily discernible. (Water Quality Field Guide, USDA, 1988)

In agricultural systems, nonpoint pollutants include fertilizers and chemicals used in crop production, and animal waste runoff.

coliform bacteria

A group of bacteria predominantly inhabiting the intestines of man or animal but also found in soil. While harmless themselves, coliform bacteria are commonly used as indicators of the possible presence of pathogenic organisms. (Water Quality Field Guide, USDA, 1988)

Fecal coliform (e.g. E. coli) is a specific type of coliform bacteria. Their presence in drinking water indicates contamination by human or animal waste.

Nitrate-Nitrogen

A form of nitrogen commonly found in water, nitrate-nitrogen (or "nitrate") is absorbed readily by plants. This property makes it a popular choice for a plant fertilizer. However, nitrate is very soluble in water. If the amount of nitrate in the water or soil exceeds the plant's demand, the remaining nitrate can be transported with water to surface or ground resources.

At high levels, nitrate can have serious health effects on infants and livestock. The most serious condition is known as methemoglobinemia, or "blue baby syndrome". The EPA's health advisory limit for nitrate in drinking water is 10 milligrams/liter.

pesticides

A chemical substance used to kill or control pests such as weeds, insects, algae, rodents, and other undesitable agents. Includes herbicides, insecticides, miticides, nematicides, rodenticides, fungicides, plant growth regulators, and desiccants.

Misuse of pesticides may cause damage to human health and the environment.

unconfined aquifers

Groundwater exists within aquifers under two basic physical conditions: confined or unconfined. Confined aquifers are "trapped" by bedrock or some type of impermeable material. Water is under pressure in confined aquifers, and is recharged slowly. In Iowa, these aquifers begin several hundred feet below the surface. Unconfined aquifers are characterized by a lack of overlying confining material (e.g. bedrock). They are located in the upper portion of the earth's crust, starting at ground level. These aquifers are very common in Iowa, and generally yield large amounts of water. However, due to their close proximity to the surface, they are more at-risk to pollution.

water table wells

Wells fed from unconfined aquifers, and constructed at very shallow depths (usually just below the water table). Also known as "seepage wells", they may yield large amounts of water, but are highly susceptible to contamination.