Every 2 years the Department of Environmental Quality (DEQ)assesses creeks, streams, rivers and ponds and lakes. They evaluate whether the water meeting criteria for six different water uses. In Loudoun County, the two water uses of primary concern are recreational use (swimming) and aquatic life (things living in the streams such as macro invertebrate). The DEQ looks at bacteria levels for recreation and sediment and other pollutants that impact the aquatic bugs. If criteria are not met, DEQ submits the data to EPA, who then adds the stream reach to the "list" of impairments. Some, but not all impairments require further action, such as evaluation how much the pollution (typically bacteria or sediment) need to be reduced in order for the stream to meet water quality standards and be removed from the "list."
