“Significant” impacts from Monterey desalination says draft report

Whichever of the three desalination-based proposals for future water supply on the Monterey peninsula in California is eventually implemented, there would be “significant and unavoidable” environmental impacts.

This is a major conclusion of the environmental impact report (EIR) published on 31 January 2009 for the CalAm Coastal Water Project.

The EIR, prepared by the California Public Utilities Commission (CPUC), examines three possible projects:

  • A 10 MGD (37,500 m³/d) desalination plant at Moss Landing using the existing cooling water source for the Moss Landing powerplant as a source;
  • An 11 MGD (41,600 m³/d) desalination plant at North Marina using six new subsurface intakes involving slanted wells;
  • A two-phase Regional Project using a 10-13 MGD (37,500-49,000 m³/d) North Marina desalter fed from 5-15 vertical beach wells, but also involving the existing Salinas River Diversion Facility and a new surface water treatment plant.
  • While most impacts can be mitigated, the EIR assesses that areas where “significant and unavoidable” impacts will occur include:

  • Greenhouse-gas emissions, where the preliminary draft significance threshold set by the California Air Resources Board would be exceeded for all proposals both during and after construction;
  • Air quality, with the two-phase Regional Project likely to exceed the PM10 (particulate matter) limit, set by the local air-pollution control district, during construction;
  • Excessive noise during construction of all three projects;
  • Liquefaction and related ground failure in the dune storage area proposed under the Regional Project in the event of an earthquake;
  • A considerable growth impact as a result of the second phase of the Regional Project.
  • The EIR also details unresolved issues and areas of controversy. These include:

  • The future of once-through cooling at the Moss Landing powerplant, now under increasing scrutiny due to entrainment and impingement of marine organisms at the seawater intakes;
  • Appropriate use of recycled water and recycled water infrastructure from the Salinas Valley Reclamation Project: how the recycled water is used, who has rights to use or deliver it, and what facilities are used for its delivery.
  • Public versus private ownership of a desalination facility in Monterey County: By Monterey County ordinance, private companies cannot own a desalination project. CalAm is a private investor-owned utility.
  • A 60-day public comment period on the draft EIR will end on 1 April 2009. A full EIR will then be published in mid-2009. The draft EIR can be viewed on the CalAm Coastal Water Project website .