A protestor was arrested Friday at Portland's Mount Tabor.
Police say the man was putting up signs in violation of park rules.
Police asked him to leave, but 66-year-old Michael Meo refused.
Meo is part of a protest against water policies that call for draining Mount Tabor's historic reservoirs.
City officials have said the group will not be allowed to stay overnight, and that a midnight curfew will be enforced.
Organizers with Occupy Mount Tabor say they intend to stay put. Meo was charged with Criminal Tresspass, and taken to the Multnomah County jail.
This story originally appeared on Oregon Public Broadcasting.