The Patrick administration’s top environmental official says he is comfortable with the level of environmental monitoring at Pilgrim Nuclear Station and believes the plant should be relicensed by the federal government.

Ian Bowles, the secretary of energy and the environment, said he spent a half-day at the Plymouth plant on April 1 to better under its testing protocols for tritium, a radioactive substance that has been found in water near the Vermont Yankee nuclear plant.

“I felt comfortable following my trip down there,” Bowles said. “On the basis of the assurances that I got when I was there, I’m comfortable with them being relicensed.”

Bowles’s positive comments about Pilgrim were the administration’s first since February 11, when Gov. Deval Patrick wrote a letter to the Nuclear Regulatory Commission urging the agency to hold off on its relicensing deliberations involving Pilgrim until more extensive testing for tritium leaks is conducted.

The Pilgrim nuclear plant’s license is scheduled to expire in 2012; it is seeking a 20-year extension. Both the Vermont Yankee and Pilgrim plants are owned by Entergy Corp. of New Orleans.

David Tarantino, a spokesman for Pilgrim Station, called Bowles’s comment a very positive sign. “We’re really happy that he and Ann Berwick [undersecretary of energy] took the time to come to Plymouth to see the level of monitoring we do and the care we take to protect the environment,” he said.

Mary Lampert of PilgrimWatch, a watchdog group, said Bowles shouldn’t base his opinion of Pilgrim’s safety on a half-day visit to the plant. In an email, she said: “Ian Bowles’s Pilgrim Station public relations tour could not provide him or anyone else, including a trained nuclear engineer, with the ability to make an assessment of the ongoing safety of the reactor. Therefore, unless Bowles received specific commitments for mitigation to prevent and detect leaks of radioactive liquids from buried components, he is at odds with the governor. Unless he received a specific commitment to increase overall security to reduce the vulnerability of Pilgrim’s spent fuel pool, he is at odds with the Massachusetts Attorney General. Unless he received in addition specific commitments on a host of other public safety issues, he is at odds with the interests of the citizens of the Commonwealth.”