EPAL - Empresa Portuguesa das Águas Livres - Portuguese Water Company (formerly Lisbon Water Company).
On the same day, a photo was taken near the current lid, an identical lid but with a thicker frame Click for a larger image
And also on the same day at Praça do Município 24, 1200-005 Lisboa, Portugal an identical cover was photographed but surrounded by a square frame Click for a larger image