(Adds details on Shell's plans, local protests)
By Eric M. Johnson and Timothy Gardner
SEATTLE/WASHINGTON, June 29 (Reuters) - Royal Dutch Shell could begin drilling for oil in the Arctic off Alaskaas early as the third week in July, when it expects sea ice tobegin clearing, a spokesman said on Monday.
The Polar Pioneer drilling rig arrived in Dutch Harbor, inUnalaska, off mainland Alaska, early on Saturday morning andwill remain there until ice begins clearing over the area in theChukchi Sea where the company plans to drill through lateSeptember, spokesman Curtis Smith said.
"As of today, our in-house experts are forecasting the thirdweek in July will present the first opportunity to begindrilling operations over our Burger prospects," Smith said in astatement.
The company was given a conditional green light by the U.S.Department of the Interior in May to return to the Arctic forthe first time since its mishap-plagued 2012 drilling season.
Assuming necessary permits are in hand, the company'sequipment would be in place after the first week in July, Smithsaid. The 2015 drilling season will include two drilling rigsand at least 25 support vessels.
Although the start date is about a week later than the July15 date when the company is allowed to begin drilling, Smithsaid it will still amount to an earlier opening than theprevious 11-year average by almost three weeks.
The drilling plan has become the target of a major campaignby environmentalists opposed to oil and gas exploration in theArctic, where they fear a potential leak would do irreparabledamage to a pristine environment home to polar bears andwalruses.
Environmentalists also say the initial project couldincrease development of the Arctic and threaten the region'svast layer of sea ice that helps regulate global temperatures.
Smith said the drilling window is subject to change,depending on the ice.
Meanwhile, activists in Washington state scrambled tomobilize a water-borne protest early on Monday when the secondrig, the Noble Discoverer, maneuvered from a port north ofSeattle for what Shell said was a planned procedure to calibratepositioning equipment.
Activists, who thought the Noble Discoverer was headed toAlaska, called on sympathizers to meet at a ferry dock wherethey could launch kayaks in a bid to block the rig's path.
"Shell's rig was unable to depart Everett and has re-dockeddue to 'calibration failure,'" protesters wrote.
Over past two months, activists have staged frequentdemonstrations. A similar flotilla-style protest involvingkayaks in Seattle earlier this month failed to block the firstrig from departing for Alaska.
(Reporting by Eric M. Johnson in Seattle and Timothy Gardner inWashington, D.C.; Editing by Cynthia Johnston, Sandra Maler andLeslie Adler)