Glossary 303(D) LIST A list held by the State as required by Section 303(d) of the Federal Clean Water Act of the waterbodies that do not support their designated uses. The Tennessee Department of Environment and Conservation publishes this list every two years: http://tn.gov/environment/wpc/publications/. AQUIFER An underground layer of permeable rock containing or conducting groundwater. Sub-surface rock types commonly containing aquifers include sandstone, conglomerate, fractured limestone and unconsolidated sand and gravel. ATMOSPHERIC VOLATILIZATION Loss of a substance to the atmosphere as a gas (in a gaseous state), such as nitrogen-based fertilizer applied to soil surface that may evaporate as gaseous ammonia. BASIN A physical facility that holds stormwater. BEST MANAGEMENT PRACTICES, STORMWATER (BMP) A method that is recognized as an efficient, effective, and practical means of reducing stormwater runoff quantity and preventing or reducing the
movement of pollutants into receiving waters. A BMP may be a physical facility or a management practice achieved through action. BIOACCUMULATION The process by which contaminants accumulate within the tissues of a living organism. BIOCHEMICAL BREAKDOWN Metabolic processes that break down or degrade contaminant compounds into simpler molecules or elements. BIOLOGICAL DIVERSITY (BIODIVERSITY) The number and variety of living organisms in a defined geographic area in all forms and at all levels, including ecosystem diversity, species diversity, and genetic diversity. BIORETENTION A process enabled by various stormwater best management practice facilities where runoff is captured and pollutants are filtered through physical, chemical, and biological processes. Bioretention facilities are sized to retain a prescribed stormwater runoff volume, designed with specific vegetation and engineered media, and usually incorporate an underdrain to route treated water to a receiving drainage system. 193