A contractor working for the state of Georgia has reached depths of 1,200 feet below the Earth’s surface in an ongoing effort to find a new source of water for Tybee Island. In an email to the Savannah Morning News last week, Andrew Morris, a senior program manager with the Georgia Environmental Finance Authority, reported that Bloomingdale-based Layne Christensen Co., still has another 2,800 feet to go before the drilling will reach its target — the Cretaceous aquifer, a deposit of hot, salty water some 4,000 feet below the surface. He said he expects the drilling, which began in November, to be complete by the end of June. The authority is digging the well at the Tybee Island Public Works department on Polk Street. Island officials hope the well — a $4.8 million expense being borne by the state as part of Gov.