Las Tablas and Lake Nacimiento Mercury TMDL


Problem Statement - The historic processes of mining have caused mercury impairments in Lake Nacimiento and Las Tablas Creek. Water samples from these waterbodies consistently show mercury at levels in excess of Basin Plan objectives for “freshwater habitat” (cold and warm waters) beneficial uses. In addition, fish tissue samples collected from fish in Lake Nacimiento between 1981 and 1994 exceed US Food and Drug Administration levels for human consumption. This is an impairment of narrative standards for suspended and settleable materials and indicates impact to the beneficial use of “commercial and sport fishing."


  • May 16, 2003 - Central Coast Water Board adopts the Las Tablas and Lake Nacimiento TMDL
    • Staff Report
    • Resolution not posted because the TMDL is not adopted.
    • Attachment 2 - Project Report (technical report that provides the basis for the TMDL)


Status and Public Notices

  • Status: Central Coast Water Board adopted in 2003, however, neither State Board nor USEPA approved. TMDL project indefinitely postponed until USEPA takes further action regarding potential superfund site.
  • Public Notice: none at this time.

Approval status

  • Central Coast Water Board
    - adopted May 16, 2003.