A new process for the production of methane gas from flush dairy operations utilizing heated baffles in a lagoon is disclosed. The baffles are aligned in rows with the rows oriented perpendicular to the flow of nutrient-rich liquid through the lagoon. The baffles are indirectly heated by either hot water or steam and are suspended sheets of porous material upon which methane-producing bacteria are resident. The methane is contained beneath and removed from an enclosing cover over the lagoon.