Saraswati was arrested as he refused to end his fast despite his deteriorating health, Haridwar District Magistrate Sachin Kurve said.
The activist was later produced in the court of CJM Varun Kumar who sent him to 14 days' judicial custody, the official said, adding that he has been lodged in Roshnabad jail.
"We had taken medical opinion on his health and doctors had advised him to end his fast immediately," he said.
However, the activist's fast continues as he is taking nothing but lime water thrice a day, the District Magistrate said.
The 'Save Ganga activist had been on a fast unto death since December 10 at Haridwar's Matrisadan Ashram to protest resumption of quarrying and stone crushing in the ecologically sensitive areas along the river in alleged violation of the Ministry of Environment and Forest norms.
"As he declined to break his fast till the government withdraws its December 1 order allowing resumption of these activities despite repeated pleas by us, we had no choice but to arrest him," Kurve said.
A team of officials led by Haridwar SDM Arvind Pandey had made an infructuous attempt to persuade Sarawati to end his fast yesterday.
Saraswati had shut himself in a room on Thursday to foil any attempt by officials to forcibly shift him to a hospital.
