Many industries are required to develop and implement a storm water monitoring plan in order to monitor storm water runoff from their facilities. This plan may include the testing of various chemical and physical parameters for one or two significant rainfall events per wet season. In addition to chemical/physical testing, (or as an alternative to the chemical analysis of a possible endless list of likely contaminants), facilities may need to conduct a percent survival test. Many aquatic toxicity tests are available, however, most regions follow EPA's acute aquatic toxicity manual (EPA/600/4-90/027F). The test protocol consists of simply placing test organisms in 100% storm water samples and laboratory control water. Water quality parameters and survival are then monitored daily for the duration of the test. Results are expressed as the final percent survival rate in the storm water sample. The most commonly used test organism is the fathead minnow (Pimephales promelas). Water fleas, (either Ceriodaphnia dubia or Daphnia pulex) or other fish may be required in a 48 or 96 hour test. Please check with local regulators or the NPDES permit regarding which protocol is required.