The protest took place three days before an all party delegation led by Chief Minister Pramod Sawant is scheduled to meet Union environment minister Prakash Javadekar to urge him for the 'revocation of consent'.
Speaking to reporters, Prajal Sakhardande, a historian, said that the diversion of the water of the Mhadei river to Karnataka's Malaprabha river basin would severely damage Goa's ecology and the water table.
"Goa's very future is in peril. A drop in the water levels of the Mhadei river will adversely impact flora and fauna, agriculture, even the drinking water security of Goa," Sakhardande said.
President of the Congress's women's wing Pratima Coutinho said that the decision of the Union Ministry for Environment and Forests to grant the clearance to the Karnataka government project was "illegal".
"The Mhadei is a multi-state river flowing through Karnataka, Maharashtra and Goa. The biggest section of its basin is in Goa, so why was Goa not consulted before such a decision was taken by the MoEF. There is politics behind this decision," Coutinho said.
The Congress has also alleged that the MoEF approval to the water diversion project, which ostensibly aims to cater to the drinking water needs of the residents of large parts of North Karnataka, was "political in nature with an eye on electoral gains" during the upcoming by-elections in the Southern states.
The protests staged by the Opposition and civil society come three days before Sawant is expected to lead an all-party delegation to the national capital, to discuss the issue with Javadekar and urge him to withdraw his ministry's nod to the controversial project.
The main Opposition party in Goa, the Congress is also expected to join the delegation.
( With inputs from IANS )