The definitions and associated explanations of water-related terms presented here are intended to provide the reader with a working knowledge of terms that apply to Virginia's water resources. The list is designed to assist the user in understanding and interpreting water related information that may come from sources as varied as governmental agencies, environmental groups, or the news media. While terms and definitions are fairly consistent, some terminology presented here could be defined differently to describe water resources issues in other locations.

Composting is a degradation process brought about by bacteria and fungus organisms. Large amounts of organic kitchen, garden, lawn, and/or farm refuse can be reduced in a relatively short time to a pile of black, crumbly humus which makes an ideal soil conditioner. Compost added regularly to soil will inevitably benefit the soil. The soil's structure will improve, since humus contains substances which cause aggregation (sticking together) of soil particles. In a clay soil this means that the microscopic individual particles will be clumped together and more air spaces will be opened up between clumps. Without these air spaces the clay particles stick tightly to each other, forming a nearly impenetrable barrier to water and gases. 

Every home kitchen generates food scraps for disposal. Throwing these scraps in the garbage can create odor problems and adds to the volume of waste going to the landfill. Disposing of kitchen scraps in a garbage disposal is convenient, but it adds to the burden of the waste-treatment system and throws away a potentially valuable resource. Furthermore, garbage disposals are not recommended for homes that rely on a septic system for waste disposal. A viable alternative to disposing of food scraps in the landfill or the sewer system is to compost them. The resulting material is a useful addition to gardens and potted plants.

Ethanol is produced when starch in corn grain is fermented. Most other constituents in the grain remain unchanged. The end product of the corn is distiller’s grains or DDGS (distiller’s grains with solubles). The DDGS retain the original fatty acids, protein, and phosphorus. In addition, variability in the grain nutrient content used in the fermentation process and the actual process itself results in a feed with variable nutrient content. Distiller’s grains can be fed either in the wet (less than 25 percent dry matter) or dry (greater than 85 percent dry matter) form. Wet DDGS are difficult to store and must be fed within a few days of production. The wet DDGS can be the most cost-effective, however, if used close to where they are produced.

The people of Virginia use nearly 400 million gallons of groundwater each day to meet industrial, agricultural, public, and private water demands. One-third of Virginia's citizens rely on groundwater as their primary source of fresh drinking water, and 80 percent of Virginians use groundwater to supply some or all of their daily water needs. Groundwater is an important resource, but it is a hidden one and, therefore, is often forgotten. In fact, until recent incidents of groundwater contamination, little attention was paid to the need to protect Virginia's groundwater.

A TMDL, or total maximum daily load defines the total pollutant loading a water body can receive and still meet applicable water quality standards. (Italicized terms are defined in the boxes at the bottom of each page.) A TMDL equation is developed from a study that identifies the sources of a particular pollutant in a watershed, the pollutant contribution from each source, and the pollutant reduction required to attain and maintain water quality standards. In TMDL calculations, all identified sources of the particular pollutant are quantified, including both point and nonpoint sources of pollution. Because some TMDL calculations involve assumptions and professional judgment, TMDLs also include a margin of safety to account for uncertainty. (See TMDLs [Total Maximum Daily Loads]: Terms and Definitions, Virginia Cooperative Extension publication 442-550, http://pubs.ext.vt.edu/442-550/.)

Microbial Source Tracking (MST), also commonly referred to as bacterial source tracking (BST), is a method used to determine the sources of fecal bacteria and establish whether fecal bacteria are being introduced into water bodies through human, wildlife, agricultural, or pet wastes. MST is considered to be a novel technology still in developmental stages. However, the use of MST is rapidly becoming widespread as more researchers and states are recognizing its potential.

The purpose of this publication is to describe on-site technologies for treating domestic sewage where conventional means (public sewer or septic tank with drainfield) are not available. These technologies are described as alternatives in this publication. Our goal is to provide information that can be used by property owners and residents to initiate action to rectify sewage-disposal problems, especially where current wastewater treatment is inadequate. This work is intended to provide information on alternative wastewater treatment options that will help the reader to make informed decisions when dealing with oversight agencies and contractors; it is not intended to serve as a stand-alone reference for design or construction.

Research has shown that consumers find reading and understanding the label to be the most difficult aspect of applying pesticides. However, an understanding of the label information is essential before work begins. The label printed on or attached to a container of pesticide tells how to use it correctly and warns of any environmental or health safety measures to take. Read the label when you purchase a pesticide and again before mixing or applying it. If you are confused about any part of the label, consult your Extension agent or a representative of the company that makes the product. Many pesticides now list a toll-free number for consumers. The label includes specific information that you should be aware of and learn to understand.

Phosphorus (P) is a naturally occurring element that can be found in the earth's crust, water, and all living organisms. Phosphorus (P) is one of 16 elements that are essential for plant growth. Soils in Virginia are naturally low in phosphorus, and most cropping systems on these soils require supplemental phosphorus to maximize their yield potential.

Did you know that livestock, like humans, prefer a clean water source and are healthier and more productive when they drink clean water? Virginia producers who have restricted or eliminated livestock access to streams and farm ponds and converted to a clean, alternative water source have observed increased livestock productivity, improved water quality, and restored stream banks on their farms. As a consequence, livestock stream exclusion practices are gaining popularity across Virginia. This publication, produced through the cooperation of Virginia Cooperative Extension and the Virginia Department of Conservation and Recreation, describes the findings, experiences, and successes of individual producers who are limiting livestock stream access.

A water-quality "impairment" exists if a body of water is unable to support its designated uses. (Italicized terms are defined in the boxes at the bottom of each page.) Virginia's water-quality standards specify that surface waters are either designated for "recreational use" (e.g., swimming, fishing, and boating) or "aquatic life use" (e.g., viable fishing populations). To support the "recreational use," the state sets numeric waterquality criteria for the maximum amount of bacteria in surface waters (Escherichia coli (E. coli)) for fresh water and enterococci for marine waters). When the concentration of bacteria exceeds the state-specified water-quality criteria, the water does not support the designated recreational use and is deemed to have a bacteria or pathogen impairment. E. coli and enterococci bacteria are found in the intestinal tracts and feces of warm-blooded animals, including humans. High counts of these bacteria indicate the presence of fecal contamination in water.

The definitions of TMDL-related terms presented here are intended to provide the reader with a working knowledge of terms that apply to Virginia's TMDL program. This is the first in a series of Virginia Cooperative Extension publications that deal specifically with TMDLs. The federal Clean Water Act requires States to develop TMDLs for streams, rivers, lakes and estuaries that do not or are not expected to meet applicable water quality standards. This glossary is designed to assist the reader in understanding and interpreting TMDL related information that may come from sources as varied as governmental agencies, environmental groups, consulting firms, or the news media.

Aphids (Hemiptera: Aphididae)

(numerous aquatic plants)

Aphids are often called plant lice. Several species are troublesome pests on above-water leaves (a), stems, and flower buds of aquatic plants. These sucking insects distort succulent new leaves, causing them to curl, wilt, or turn yellow. Adults are 1/8 inch long and can be winged (c) or wingless (b) with soft pear-shaped bodies with two distinctive cornicles or "tailpipes" protruding from the backs of their abdomens. 

Water reuse can be defined as the use of reclaimed water for a direct beneficial purpose. The use of reclaimed water for irrigation and other purposes has been employed as a water conservation practice in Florida, California, Texas, Arizona, and other states for many years.