The San Diego Regional Water Quality Control Board is testing the use of biological performance as an enforceable standard in the San Marcos Creek District permits. The California State Water Resources Control Board and U.S. Environmental Protection Agency are using this as a pilot and working toward a statewide expansion of the standard by 2014. Biological assessments will start with benthic macroinvertebrates as key indicators. In comparison with sampling for chemical contaminants, which shows a snapshot of water quality, biological indicators tell a long-term tale of stream health. Read more about biological indicators.