X. Hannibal, Donna, Florence and Joel, concerned residents of Laguna de Bay, filed a complaint for mandamus against the Laguna Lake Development Authority, the Department of Environment and Natural Resources, the Department of Public Work and Highways, Department of Interior and Local Government, Department of Agriculture, Department of Budget, and Philippine National Police before the R TC of Laguna alleging that the continued neglect of defendants in performing their duties has resulted in serious deterioration of the water quality of the lake and the degradation of the marine life in the lake. The plaintiffs prayed that said government agencies be ordered to clean up Laguna de Bay and restore its water quality to Class C waters as prescribed by Presidential Decree No. 1152, otherwise known as the Philippine Environment Code. Defendants raise the defense that the cleanup of the lake is not a ministerial function and they cannot be compelled by mandamus to perform the same. The RTC of Laguna rendered a decision declaring that it is the duty of the agencies to clean up Laguna de Bay and issued a permanent writ of mandamus ordering said agencies to perform their duties prescribed by law relating to the cleanup of Laguna de Bay.