From a Washington State Patrol press release:

Washington State Patrol’s Impaired Driving Section and the Mercer Island Police Department are making preparations for boater and spectator safety during this year’s Seafair celebration.  One of the largest Impaired Boating Emphasis in the nation will focus its efforts to improve safety during Seafair activities on Lake Washington August 3-5, 2012.

The participating agencies involved will include: Mercer Island Police & Marine Patrol, Washington Department of Fisheries and Wildlife, Seattle Police & Harbor Patrol, King County Sherriff’s Office Marine Patrol, United States Coast Guard, and the Washington State Patrol.

This year’s event will once again be located at Proctor Landing on Mercer Island. To accommodate the Marine Patrol Units, a temporary sixty foot dock will be located at the site. In addition, the Mobile Impaired Driving Unit will be on site. It is equipped with 3 breathalyzer instruments, two holding cells and serves as a command vehicle to coordinate with the various law enforcement jurisdictions participating in the emphasis.

To ensure safety at the scene, several large fenced detention facilities will be located to accommodate subjects arrested for boating under the influence, minor in possession or consumption of alcohol, and other violations.  Several troopers or officers will be assigned to work security posts at these locations throughout the event. A prisoner support vehicle will be utilized to transport those persons arrested to the appropriate jail facility.

Additional DUI patrols will be scheduled throughout the weekend. They will focus their efforts on the roadways leading to and from the event. In addition there will be drug recognition experts available for drug impairment evaluations.

To assist in case preparation and any legal issues that may arise, members of the King County Prosecutors office will be on site to assist in the processing of the arrestees. Trained law enforcement officers and troopers are equipped to remove any vessel from Lake Washington if it is determined that it’s driver or passengers are impaired and cannot continue to operate it in a safe manner.

Past Seafair Weekends:

• In 2008 83 boating under the influence and 47 DUI arrests were made in King County.
• In 2009 110 boating under the influence and 53 DUI arrests were made. Also, 7 minor in possession arrests were made and 688 vessels were contacted. No major boating collisions occurred.
• In 2010 463 vessels were contacted with 59 boating under the influence arrests and 3 counts of reckless endangerment of a minor. On King County roadways 54 DUI arrests were made.
• In 2011 536 vessels were contacted with 70 boating under the influence arrests.  On King County roadways 57 DUI arrests were made.

The successful implementation of this maritime safety emphasis that is scheduled to coincide with the Seafair activities continues to provide a safe, enjoyable environment for all. It is estimated that between twenty and thirty thousand boats could participate in this year’s event. The number of attendees could exceed three hundred fifty thousand people. This event remains the highest attended summer event in Seattle.