PHOENIX (AP) _ A member of the environmental group Earth First 3/8 was sentenced Friday to six years in prison for his role in an alleged conspiracy to damage nuclear installations in three states.

Mark Davis' sentence was the maximum permitted under an agreement in which he pleaded guilty to malicious destruction of property at Snowbowl ski resort near Flagstaff.

U.S. District Judge Robert Broomfield also accepted plea bargains on behalf of the four other defendants in what authorities said was a conspiracy to damage nuclear sites in California, Colorado and Arizona.

Vandalizing the ski resort, damaging power poles near a uranium mine near the Grand Canyon and damaging power lines leading to an Arizona aqueduct were seen as rehearsals for the larger projects to come.

Broomfield ordered Davis to report for prison Sept. 23. Davis had asked for time to get his affairs in order and an opportunity to spend time with his daughters.

Davis also was ordered to pay about $20,000 restitution for the ski resort damage.

In a lengthy and emotional statement, Davis told the judge he acknowledged his actions and his responsibility for them but also said he was trying to protect himself and others against the potentially deadly danger of nuclear plants.

''I'm not an anarchist, I'm not a terrorist, I'm not a revolutionary,'' he said. ''What I did was an attempt to wake people up.''

His attorney, Wellborn Jack Jr., said Davis ''knows as a participant in this trial that 'monkeywrenching' as a form of environmental activism, as a political expression, is dead.''

The term applied to acts of environmental protest and came from a book by the late environmentalist Edward Abbey. The book gave rise to an activist organization Earth First 3/8, and its founder, Dave Foreman of Tucson, was among the defendants.

Broomfield dismissed the jury that had heard nearly two months of testimony before the trial in Prescott was interrupted by the surprise plea-bargain proposals. One of the other defendants is to be sentenced Monday; the others Sept. 19.

In sentencing Davis, Broomfield said he believes Davis knows what he did was wrong but doesn't feel sorry for doing it.

Davis, a Prescott cabinetmaker, could have been fined up to $250,000.

Prosecutors said the defendants had targeted the Rocky Flats nuclear weapons plant outside of Denver, the Diablo Canyon Nuclear Generating Facility near San Luis Obispo, Calif., and the Palo Verde Nuclear Generating Station west of Phoenix. None of those attacks was carried out.

Besides Davis and Foreman, the defendants were Ilse Asplund, 37, Margaret ''Peg'' Millett, 37, and Mark Baker, 39, all of Prescott.

Foreman, 44, pleaded guilty to one felony count of conspiracy, which carries a five-year maximum term. If he abides by the terms in the plea bargain, the sentence would be delayed five years in which he could plead guilty to a misdemeanor without further penalty.

Ms. Millett pleaded guilty to aiding and abetting in the malicious destruction of property; maximum sentence could be three years in prison and $250,000.

Baker, a botanist, and Ms. Asplund, an AIDS counselor, pleaded guilty to failing to report a felony; each could be sentenced to one year and a day in prison and a $250,000 fine.