WASHINGTON – The State Department on Friday removed a major roadblock to a planned $7 billion oil pipeline from western Canada to the Texas coast in a report that says the project is unlikely to cause significant environmental problems during construction or operation.

The thousand-page report on the proposed 1,700-mile Keystone XL pipeline says no significant problems have emerged since a similar report was issued last year.

Calgary-based TransCanada wants to build a massive pipeline to carry crude oil extracted from tar sands in Alberta to refineries in Texas. The pipeline, which would travel through Montana, South Dakota, Nebraska, Kansas and Oklahoma, would carry an estimated 700,000 barrels of oil a day, doubling the capacity of an existing pipeline from Canada. Supporters say it could significantly reduce U.S. dependence on Middle Eastern oil.

The project has become a flashpoint for environmental groups who say the pipeline would bring “dirty oil” that requires huge amounts of energy to extract and could cause an ecological disaster in case of a spill.

Opponents of the pipeline have urged the Obama administration to block the project as a sign he is serious about protecting the environment.

Several hundred activists, including actress Margot Kidder and prominent scientists, have been arrested in recent days in protests outside the White House. Organizers say the protests are the largest acts of civil disobedience centered on the environment in many years.

TransCanada maintains that the project would create tens of thousands of jobs and would be built to strict environmental standards, including 57 conditions above those required by law.

For example, the company has agreed to build much of the pipeline 4 feet below ground, instead of the usual 3 feet. Depths will increase to 25 feet below ground at several hundred river crossings along the proposed route, which passes through the Ogallala Aquifer, an environmentally sensitive formation that provides groundwater to eight states in the Great Plains.

TransCanada also said it will allow an increased number of inspections and install a greater number of safety shut-off valves than usual.

The State Department report cites those conditions as among the reasons for its confidence in the project. The report endorses the current proposed route, which has drawn criticism from officials in Nebraska and other states as environmentally risky.

Kerri-Ann Jones, an assistant secretary of state, said the report was “not a rubber stamp for this project,” adding, “No decision has been made.”

The report, the third environmental analysis submitted by the State Department since last year, kicks off a 90-day review of whether the project is in the “national interest” before a final decision is issued by the end of the year.