New: On July 6, 2012, the International Maritime Organization (IMO) Safety of Navigation Sub-Committee approved the U.S. proposal to ajust the traffic separation schemes in the Santa Barbara Channel, moving the southbound lane one mile further away from an area within the sanctuary known to be a seasonal feeding ground for endangered blue whales. The proposals will next go before the IMO Maritime Safety Committee in November, 2012. This proposal to adjust the lane derived from a Coast Guard study, see below.

Local Impacts of Marine Shipping  |  Local Studies & Actions |  State/National/ International Initiatives  |  Related Downloads/Links |  Past Activities

International Action

In 1973, an international conference of the IMO adopted the International Convention for the Prevention of Marine Pollution from Ships (MARPOL), and an accompanying treaty (these treaties are termed “Annexes”) designed to prevent pollution from ships.

In 1997, the IMO agreed to MARPOL Annex VI, a global treaty to reduce air emissions from ships. The treaty was to become effective one year after being ratified by at least fifteen nations, representing a minimum of fifty percent of the world’s shipping tonnage. On May 18, 2004, MARPOL Annex VI was ratified by the fifteenth nation, bringing the total percent of the world’s merchant shipping tonnage to 54.57%. Annex VI went into effect on May 19, 2005.  The U.S. has ratified  MARPOL Annex VI.


  • Sets limits on sulfur dioxide (SOx) and NOx emissions from ships, and prohibits the intentional emission of ozone-depleting substances such as chlorofluorocarbons.
  • Sets a global limit on the maximum allowable sulfur content of fuel oil used in shipping to 4.5% m/m, and call for the IMO to monitor the worldwide average sulfur content of shipping fuel.
  • Establishes specific “SOx Emission Control Areas” with more stringent controls on SOx emissions (1.5% m/m).
  • Prohibits on-board incineration for ships carrying certain products.

North American Emission Control Area

North American ECA mapOn March 26, 2010, in response to a request from the U.S. and Canada, the IMO officially designated the North American Emission Control Area (ECA). Stricter fuel and engine standards apply in waters up to 200 nautical miles from the coasts of the United States, Canada and the French territories. The fuel sulfur limit drops to 0.1 % in the ECA in 2015. The area covered is depicted below; for more information see Environmental Protection Agency web page.





U.S. Action

Environmental Protection Agency

In a rule published on April 30, 2010, the U.S. Environmental Protection Agency (EPA) adopted standards that apply to Category 3 (C3) engines installed on U.S. vessels and to marine diesel fuels produced and distributed in the United States. For more information, see this page on EPA’s website. On March 30, 2009, the EPA announced that the U.S. would ask the IMO to create the ECA referenced above. See this page to download comment letters, and  this page to view legal actions undertaken by the District calling on the EPA to take these and other actions to control air pollution from marine shipping.

 U.S. Coast Guard

The U.S. Coast Guard initiated a Port Access Route Study in April of 2010, when ships began traveling outside the Santa Barbara Channel, where there are no internationally-designated shipping lanes. Ship operators were taking this action to avoid requirements of the California Air Resources Board’s rule, which required them to use a lower-sulfur fuel when within 24 nautical miles of the California coast. (This rule was subsequently revised to extend to 24 nautial miles outside of the Channel Islands, and ships have been returning to the route through the Channel.

The Study was issued in September of 2011.  View Port Access Route Study (PDF) The Study recommended moving the established shipping lanes in the Santa Barbara Channel closer together for better protection of the Channel Islands Marine Sanctuary.  The Study also recommended establishing another set of shipping lanes outside the Channel Islands. Since the Study was issued the Coast Guard has started the process of moving the shipping lanes closer together, but has not pursued establishing shipping lanes outside the Islands.

State Action

NOAA Plane - MaerskFor the latest information on ocean-going vessels regulations by the California Air Resources Board, see this page.

In July of 2009 a California Air Resources Board rule requiring the use of lower-sulfur fuel when within 24 nautical miles of the California coast took effect. As noted above, some ship operators chose to travel outside of the Santa Barbara Channel. Since the rule was extended to 24 nautical miles outside the Channel Islands (effective December 2011), some ships have returned to the inside-the-Channel route.

Results from a study published in 2011 documented the emissions benefits from the fuel rule. A National Oceanic and Atmospheric Administration (NOAA) plane flew over a Maersk container ship in the Santa Barbara Channel and measured emissions from the ship’s stack before and after the switch to the lower-sulfur fuel and a reduction in speed. Emissions of sulfur dioxide and particulate were reduced by 90%, and significant reductions in air toxics and black carbon were also achieved.  The study did not measure NOx emissions; these were estimated to be reduced by 5-7%.

Rules Timeline

See chart below for overview of timeframe for rules taking effect.

Shipping Rules Timeline