Toxic pollutants are different from conventional pollutants such as sediment and bacteria in that they can cause biological impairment at low concentrations due to their high toxicity. Many toxic pollutants tend to bioaccumulate, in other words, their concentrations will increase along the food chain. Many are persistent and tend to attach onto suspended and bedded sediments, therefore the period of impact can greatly exceed the period of discharge.
The Santa Ana Regional Water Quality Control Board is currently dividing the Toxics TMDL into five separate TMDLs based primarily on chemical class, and developing individual implementation plans for each TMDL. These TMDLs include:
Development of the selenium TMDLs and selenium site-specific objectives (SSOs) are being supported by the efforts by the Nitrogen and Selenium Management Program (NSMP), which is a watershed-wide collaborative effort to address nitrogen and selenium issues. The County of Orange is responsible for administering and managing the NSMP, as well as serving as Chair of the program. As the NSMP continues, it will be the primary mechanism for achieving compliance with the nitrogen and selenium TMDLs for Newport Bay watershed. In December 2015, a revised Selenium TMDL Staff Report was submitted to the Santa Ana Regional Board for approval. For more information, please visit Santa Ana Regional Board’s Selenium TMDL website. More background information can be accessed from NSMP's website.
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